Combi boiler for a large house
Combi boiler for a large house – natural gas (mains gas supply) or propane gas (LPG) for a central heating system and high hot water demands
Looking for a combi boiler for a large house? Here we go through the issues that you need to consider when selecting the best combi boiler for a large house to suit your requirements. Selecting the correct combi boiler size for any home, is critical, especially when your residence is a large house, with multiple radiators, or an underfloor heating system and multiple bathrooms, it then becomes vitally important if you require a high efficiency and economical boiler with exceptional hot water flow rates then we have the perfect high heating efficiency gas boilers for your large house / home/ property, which can be fired with either natural gas or LPG / Propane gas.
In a nutshell combi boilers heat water for the central heating system and hot water demands,without a storage hot water cylinder. For this reason, they can struggle to cope with high hot water demands of multiple bathrooms properties that you might have in a 4 or 5 bedroom house for example. But we have a solution to this issue with the best combi boilers for a large property -please read on
What are combi boilers, and what do they do ?
Firstly, we need to establish what a combi boiler is. Well, the boiler’s official name is a “combination boiler” – but over the years the word has been shortened just to “combi boiler”. These boilers are now the most popular type of boiler for homes, flats, etc. in the residential market in the UK. A combi boiler not only supplies the heat for the central heating of the home (i.e., central heating system), but also heats the domestic hot water demands instantaneously as a hot water tap is opened.
If you already have a regular boiler installed in your property, that is coupled up with a hot water storage cylinder that requires a cold water tank in the loft space (if the hot water storage cylinder is a vented cylinder), then installing a combi boiler means you no longer need this cold water tank anymore and recover some loft space.
Generally combi boilers need to be more powerful than regular and system boilers to do the same job, as they use a hot water cylinder to store hot water.
Another benefit of a large combi boiler is that the hot water is fed from the mains water supply, eliminating the need for a feed and expansion tank, and thus the water pressure is often higher, resulting in better hot water performance and higher energy efficiency, without the need to store hot water in an unvented cylinder, for example.
These factors make a combination boiler one of the highest efficiency boilers on the market, with an attractive low cost purchasing price, along with the lower installation costs and continual lower running costs than the older type system boilers that were extensively used with hot water cylinders in previous times in larger homes or properties with complex heating systems.
There are two main elements to a combi boiler sizing, which need to be considered when selecting the correct size large house combi boiler –
- The central heating side of the boiler– You need to establish how much of a heating load or requirement your large property will have. This is to ensure that our energy efficient boiler has sufficient capacity to heat your large home.
-
The Domestic Hot Water performance – This is the hot water that you use to bath, wash or do the dishes/kitchen use – when preparing meals etc., as you’re not storing hot water in a separate hot water tank with a combi boiler, which makes them the most efficient boilers.
We will look at both of these issues and give you the guidance to ensure that you have the best solution for your combi for a larger house or property with multiple bathrooms and high hot water demands.
Combi sizing for large house / homes / properties
The first part is the easier bit, as they say. It doesn’t matter what heat emitters you are using to heat your home, whether it be a radiator system or an underfloor heating system or even a combination of both. The principle of heat loss sizing for your property doesn’t change for conventional boilers or combi boilers, or if they’re gas and oil boilers for your heating requirements.
Basically, the fabric of your home loses heat, depending on how well insulated the building materials used, such as the brickwork, the floor and the roof. This is known as the “U “value of the materials in question.
This” U “value is official expressed as the rate in Watts [W]) at which heat transfers through 1 square metre [m²] of the surface of a buildings material when there is a temperature difference of 1ºC between the internal and external environments.
So, if you have a property built from the late 1990’s onwards then you are safe to use this ready reckoner chart. This ready reckoner table is based on a brick and block cavity wall with mineral wool insulation having a total wall thickness of 312 mm has a “U” value of 0.3 W/mtr. The building regulation from the late 1990’s specify that this “U” value must be achieved, to pass the building regulations.
You need to ensure that you have the total floor area of your home, including the ground level, 1st floor, 2nd floor etc. It is the home’s / properties total floor area you need to calculate.
| Power Output of Boiler |
Heating area with Height of 2.7 Mtrs & U Value of 0.3 |
| 4.5 kW |
~ 55 Mtrs/2 |
| 7.5 kW |
~ 85 Mtrs/2 |
| 9 kW |
~ 110 Mtrs/2 |
| 13.5 kW |
~ 165 Mtrs/2 |
| 15 kW |
~ 180 Mtrs/2 |
| 22.5 kW |
~ 278 Mtrs/2 |
| 24 kW |
~ 300 Mtrs/2 |
For example – If your 5 bedroom house or large home has a total floor area of 600 M/2, then you’re going to need a 48 kW Combi boiler (2 x 300 m2 = 2 x 24 kW – thus a 48kW output combi boiler)
If your total floor area is 440 M/2, then you’re going to need a 48 kW Combi (1 x 300 m2 = 24 kW and 1 x 165 M2 = 13.5 Kw –always go up on the chart – you can turn a combi boiler’s power output down , if you have it there , but you can never turn it up , if it doesn’t have the capacity – thus 24kw + 13.5 Kw = 37.5 kW total boiler output
How many radiators ?
Radiators come in various kW outputs. Ultimately, the number of radiators will depend on what is required to cover your property’s kW heating load requirement.
The best combi boiler is a modulating boiler
Our combi boilers for large homes are modulating boilers, which means they will automatically ramp up and down the boiler’s power to suit the central heating (radiator or underfloor) requirements. They are very clever combi boilers these days!
Domestic hot water performance of the boilers
Ok, now for the second part of a large house combi boiler – the domestic hot water performance/sizing – and these days this is the most important factor when selecting the best boiler to suit your requirements.
Hot water flow rates
A standard showerhead typically requires 7 to 8 litres of hot water per minute of water at 40C, while “green band” showerheads that meet the European Water Label’s criteria demand only 6 litres per minute. Think of this standard as an “ErP” rating for hot water bathroom products, taps, etc. for domestic properties.
Standard shower head 7 to 8 litres a minute flow rate
Please be aware that drench showers can have some huge flow rates, from 15 litres to pretty much any flow rate – 30 litres per minute is not uncommon.
Kitchen sink taps—4 to 6 litres per minute.
Sink taps, which are the standard type, have a flow rate of 4 litres per minute.
Basin/cloakroom “spray taps”—2 litres per minute— these water-saving spray taps are very popular now, as they save water and energy requirements.
Bath mixer taps – modern bath taps have an approximate demand rate of 12 litres per minute.
So by adding all your potential hot water outlets and then applying a diversity factor (a factor that not all the hot water outlets will be used at the same time), you can calculate your hot water demand for your large house combi boiler.
Combination boilers for large houses product range
Combination boilers use a plate heat exchanger to heat the domestic hot water up to temperature from the “heating water side of the boiler”. They have benefits in that they only heat the hot water when there are hot water demands; thus, they are a highly efficient boiler, and we do a range of this type of “big combi boiler” up to 100 kW of output.
50kW Combination boiler – the best combi boiler for a 4 bedroom house ?
A 50kW combination boiler – whereby the plate heat exchanger is integral to the casing of the boiler. This boiler is a modulating boiler with a heating power range of 5.29 to 53.40 kW output at 50/30°C flow and return or 4.83 to 49.19 kW at 80/60°C with 20.30 litres/min of domestic hot water with a temperature rise of 35 degrees C (the standard temperature rise for Scotland and Northern Ireland locations in wintertime conditions) or a 23.4 litres/min hot water flow rate with a 30°C temperature rise. This 30°C temperature rise is the standard temperature rise for most of the UK in wintertime conditions.
This boiler which is an “A”-rated boiler for the heating system and hot water.These are fully detailed on this dedicated webpage 50kw combi boilers which shows dimensions, performance etc. This boiler will be the best combi boiler for 4 bed 2 bathroom house in 99% of the time or a four bed house with 1 bathroom, but using a drench shower.
50kW Combi boiler or Combination boiler – gas fired – from Flexiheat UK
If you want the best combi boiler for 4 bed 3 bathroom house, then you’re probably going to need our larger models, detailed below.
Larger output gas combination boilers
We also have a 60 kW, 75 kW, or 100 kW output option for a large house combi boiler which makes these powerful combination boilers especially suitable for even larger homes such as a combi boiler for 5 bedroom house, that usually have larger hot water demands via multiple bathroom or showers, that any gas safe registered engineer can install.With these models, the plate heat exchanger is mounted directly underneath the boiler above the low loss header (picture below).
Gas combi boiler for 4 or 5 bedroom house with multiple bathrooms from Flexiheat UK
DHW heat exchanger
The large house combination boilers come with a DHW plate heat exchanger that is neatly located above the low loss header of the gas boiler.
The 60 kW model, this combination boiler is a modulating boiler with a power range of 6.44 to 62.84 kW heat output at 50/30°C flow and return or 5.75 to 57.82 kW at 80/60°C with 28.83 litres/min of domestic hot water with a temperature rise of 30 degrees C.
These can either be wall-hung boilers or floor-standing boilers when using our frame mounting kit, as seen in the picture above.
The 70 kW model, this combination boiler is a modulating boiler with a power range of 3.87 to 79.35 kW heat output at 50/30°C flow and return or 3.5 to 72.83 kW at 80/60°C with 35 litres/min of domestic hot water with a temperature rise of 30 degrees C.
These can either be wall-hung boilers or floor-standing boilers when using our frame mounting kit, as seen in the picture above.
The 100 kW model – again, this commercial boiler is a modulating boiler with a power range of 5.29 to 106.80 kW heat output at 50/30°C flow and return or 4.83 to 98.37 kW at 80/60°C with 47.28 litres/min of domestic hot water with a temperature rise of 30 degrees C.
These can either be wall-hung boilers or floor-standing boilers when using our frame mounting kit as above in the picture.
Domestic hot water production figures for our large property combination boilers – Flexiheat UK
The 75kW and 100kW large house combi boiler models mentioned above have a modulation ratio of 1:20 for greater efficiency and reduced consumption both in heating and in DHW production, whilt the 60kW has a 1:10 modualtion. Not only do these units have stainless steel heat exchangers as standard, but they actually have two heat exchangers, or boilers, as such within one casing, meaning should one fail, you still have 50% of your duty available to you (the 60kW boiler only has one heat exchanger). Another benefit is that you can service one boiler while the other is working, so there will never be any “downtime” for your heating or hot water systems, which is a great feature!
Cold water mains supply – Why it’s vital
Combination boilers also have a minus point, which really come into factor when trying to fulfil the hot water demands when used in larger homes with multiple bathrooms or many hot water taps.
A combination boiler may struggle to meet high demands for hot water because it draws all of its water supply directly from the mains water supply. An example of this is when multiple hot water taps are turned on in various bathrooms, the kitchen or other rooms within the house; you will often see a dramatic reduction in the water pressure. That’s why the flow rate of the cold water mains should match your potential hot water requirements.
Hot water cylinder ?
This is caused by the combination boiler not having the benefit of a storage hot water tank, which would meet these levels of demand. This situation used to be resolved by using a regular boiler type commonly known as gas system boilers in conjunction with an indirect hot water storage cylinder.
System boiler for a large house
We have a full range of system boilers that are used in conjunction with a hot water storage cylinder / hot water storage tank when the hot water demands of multiple bathrooms require you to store hot water when the hot water outlets demands of multiple bathrooms can’t be satisfied by the cold water mains supply that combination boilers for large houses rely on.
Obviously installation costs are more for a system boiler and an unvented hot water cylinder setup, as they are more complex heating systems with more pipe work required, but high hot water demands sometimes require this.
Control options for the boilers
You can control our combi boilers using the inbuilt LED display control panel.
However
Everyone now wants to be able to control their boiler, when they are out and about, be it travelling or at work or even on a plane – having the facility to turn your boiler on and have the house warm for when you return to it has now become almost standard. Well the good news is that a our combi boilers can do this – they have a control panel called the Cloud Warm which is an “OpenTherm Plus “compatible controller, which means you can control these combi boilers on the go.
Cloud Warm – Wireless Wi-Fi controller – can be app controlled via a phone, iPad or computer.
This means you can make your life simpler and control these combination boilers from either your mobile phone (android or apple) your PC or tablet, from anywhere in the world, as long as you have an internet connection.
What can you do with the App ?
Cloud Warm App – control your boiler on the go !
With the Cloud Warm app, you can manage your home comfort directly from your smartphone or tablet (Android or Apple). With just a touch of your finger, you can set your comfort level; the app allows you to control, regulate, and program all the parameters for managing your heating system.
- In the event of failure or an anomaly, errors can be reset remotely, thus restoring normal boiler operations and re-establishing domestic comfort.
- You can choose thermoregulation, which keeps a consistent indoor temperature even when the outside temperature changes, by using the outside temperature sensor and internal remote control to save money and improve comfort. The heating operation is therefore modulated according to the outdoor temperature and the user’s settings.
This function, which can be managed remotely, reduces unnecessary energy consumption and saves money.
Heating engineers
The last point is that all combi boilers with gas fuel types should be installed by a Gas Safe registered engineer, not just a heating engineer, to comply with the regulations and to ensure that the combi boilers are safely and correctly installed.
Hot water cylinder ?
This is caused by the combination boiler not having the benefit of a storage hot water tank, which would meet these levels of demand. This situation used to be resolved by using a regular boiler commonly known as system boilers in conjunction with a hot water storage cylinder.
System boiler for a large house
We have a full range of system boilers that are used in conjunction with a hot water storage cylinder / hot water storage tank when the hot water demands of multiple bathrooms require you to store hot water when the hot water outlets demands of multiple bathrooms can’t be satisfied by the cold water mains supply that the biggest combi boiler relies on.
Obviously installation costs are more for a system boiler and an indirect unvented hot water cylinder setup, as they are more complex heating systems with more pipe work required, but high hot water demands sometimes require this.
What are you waiting for ! Call us, for the best combination boiler for large properties
So should you be looking for a combi boiler for a large 4 bed house or for a 5 bedroom house , with 2 , 3 or even 4 bathrooms , you can now see why our combi boiler is the best option , as the element of some hot water storage , which is as small as possible , and thus saving on wasted energy , but large enough to cope with the hot water requirements of a large home or property, then please don’t hesitate to contact us at Flexiheat UK for the best combi boilers prices, using the contact us email , or alternatively give us a call on 01202 822221. As we believe we have the best combi boilers for large houses for sale on the UK and Irish market.
3 Phase Electric Boilers
/in Products /by flexiheat3 Phase electric boilers – 0.8kW to 5mW
Three phase electric boilers from Flexiheat UK
3 phase electric boilers are commonly used and installed for a central heating system and hot water (domestic hot water via a indirect hot water cylinder for high flow rates) production in locations such as large properties, guest houses, and hotels with a suitable 3 phase electric supply to the building.
Our three phase electric boilers have been specifically designed to meet the heating demands of large domestic properties and commercial buildings or spaces.
Installation can be almost anywhere in the property, as no flue or external wall is needed with a 3 phase electric boiler. Thus making the boiler easy and quick to be installed.
They are highly efficient (100% on the immersion heaters) and have high heat load matching or modulation rates, which modulates the electricity consumption and also reduces the running costs of the wet electric heating system.
Using green or renewable electricity as a heat source for the electric boiler, can ensure a carbon free central heating system.
Three phase boiler product options
FHMN3-8 This 8kW 3 phase electric system boiler,with pump and 5 litre expansion vessel,has PV solar readiness with an adjustable output range of 2kW, 4kW, 6kW, and 8kW, and a 400V 3 phase electricity power supply is required.
This 3 phase electric boiler modulates to the following power output steps:
0.8kW, 0.9kW, 0.9kW, 1.3kW, 2kW, 2.6kW, 3.3kW, 4kW, 4.6kW, 5.3kW, 6kW, 6.6kW, 7.3kW, 7.9kW
So yes, this electric boiler can be set to either 2kW, 4kW, 6kW or 8kW (technically 7.9kW, but close enough to 8kW for us), and the boiler will ramp up and down the above modulation scale depending on what the heating system demands.
FHMN3-24 A 24 kW 3 phase electric system boiler with pump and 5 litre expansion vessel,, PV solar ready – 400 Volt 3 phase electricity powered.
This 24 kW 3 phase electric boiler modulates to the following power output steps:
1kW, 2kW, 4kW, 6kW, 8kW, 10kW, 12kW, 14kW, 16kW, 18kW, 20kW, 22kW, 24kW
This 3 phase electric boiler can be set to either 12 kW, 16 kW, 20 kW, or 24 kW and will ramp up and down the above modulation scale depending on what the heating system demands.
We go all the way up to 45kW in output this domestic range of 3 phase electric boilers, and are fully detailed on this webpage – electric central heating boilers.
28kW to 96kW Output electric boilers
Our commercial 3 phase electric boilers, which are available from 28 kW to 96 kW in outputs, with stainless steel heating elements and 7 power-step output modulation for central heating only or central heating and hot water.
These electric boilers benefit from full BMS (building management system) or 0-10 volt control capabilities (commercial installations often require this control regime) with our standard “X” control panel. This range of 3 phase electric boilers can be wall-mounted or floor-mounted with our floor-mounting kit.
Our commercial 3 phase electric boilers are detailed here – 3 Phase commercial electric boilers – wall or floor mounted
Wall mounted electric commercial boilers -28kW to 96kW from Flexiheat UK – can be floor mounted with our floor mounting frame kit
Floor mounting kit to suit these boilers
Floor mounting boiler frame kit for our 28kW to 96kW Wall hung electric commercial boilers, which converts the boilers into free standing floor standing electric boilers.
Industrial three phase electric boilers – 12 kW to 5 MW
Our industrial 3 phase electric boilers start at 12 kW and go all the way up to 5 MW in output when used in cascade. With Incoloy stainless steel heating elements for long product service life and reliability.
These are fully detailed here – Industrial electric boilers
Industrial Electric Boiler Range – 12kW to 5mW Output
Three phase electric supply
Three phase systems are better suited for high-demand scenarios because they can deliver significantly more power than single-phase systems.
Three phase electric boilers deliver power more consistently compared to single-phase systems that use one alternating current wave.
Three phase electric boilers provide better load balancing by spreading the electrical load across three wires.
Three phase electric boilers use three live wires, each 120° out of sync, for more powerful heat delivery, making them ideal for large demands.
Only qualified individuals should handle electric installation of the unit to comply with safety standards and local electrical codes. A plumber or electric heating company or a combination of both can fit our 3 phase electric boilers with easy.
Electric boilers 3 phase powered from Flexiheat UK
For more information, confirm stock availability, delivery times, price offer, or to purchase our cost-effective and energy-efficient 3 phase electric boilers for flats, small or large houses, or even commercial and industrial heating schemes with 3 phase electric power supply. Delivery costs are dependent on location. Any returned electric boilers will be subject to a restocking fee.
Please contact our sales team at 01202 822221 or click our website’s email contact form to discuss your requirement.
24kW Electric Boiler
/in Products /by flexiheat24kW Electric Boiler
Electric boiler 24kW Output
Our 24kW electric boiler can be used for central heating and to produce domestic hot water as well, via an indirect cylinder. Whether the central heating system has standard radiators or underfloor heating circuits or systems, our electric boilers can do either or even both. The outcome is electric heating for a wet central heating system, with high energy efficiency.
An electric boiler stands as the ideal solution for properties that lack a mains gas supply or have flue requirements that prohibit the use of natural gas, oil (bulky external tank required), solid fuel, LPG boilers, or electric storage heaters.
All of our electric 24 kW boilers will modulate their output to the heating requirements. This reduces the electricity consumption used and, subsequently, the fuel bills and monthly running costs.
Three phase power
With a 24 kW output, these electric boilers must be powered by a three phase 400-volt electrical supply.
Three phase is not the standard household electrical connection; it’s normally fitted in commercial locations, although you can have three phase fitted as a home connection.
If you buy from a supplier or produce your electricity from renewable energy sources—such as wind energy sources or solar electric energy—then your heating and hot water systems can be zero-carbon-rated renewable electricity.
The benefits of an electric boiler outweigh the environmental impacts of existing tank based fuels (oil or LPG) or are a perfectly feasible option against most standard boilers.
Electric boiler 24kW output
We have two options. –
Electric system boiler
The most popular is a system boiler, designated the FHMN3 product code, which is a three phase 400-volt boiler with up to 24 kW of central heating output, with an internal pump and expansion vessel and advanced heating element technology.
or
Open vent boiler
We also can supply the FHM3–product code designated version with no expansion vessel (but an internal pump and expansion vessel and advanced heating element technology) for open vent heating systems, but a minimum 5-metre head (0.5 bar of pressure) is required for these boilers to work.
Dimensions of the boiler options
FHMN3 (system boiler version) and FHM3 (no expansion vessel – for open vent systems) series electric boiler 2kW to 24kW dimensions detail from Flexiheat UK
The full brochure is here for direct download.
M range electric heating boilers brochure from 1kW to 24kW of output from Flexiheat UK
The manual for this range is here:
M range electric boilers technical and installation manual 1kW to 24kW from Flexiheat UK
Smart modulating system with high modulation ratio
The modulating electronic control of these wall-mounted electric heating boilers adjusts the power levels to meet the requirements of the central heating system, whether it is for underfloor heating or radiators; this automatic heating regulation reduces energy consumption by ensuring that the boiler’s heat output matches the heating system’s demand, resulting in lower energy bills for your home.
FHMN3-24 is a 24kW electric system boiler that includes an outdoor sensor, cascade capability, a 5-litre expansion vessel, and an internal pump and is PV solar ready, with an adjustable output range of 12kW, 16kW, 20kW, or 24kW – designed for 400 Volt 3 Phase only.
This 24 kW electric boiler modulates to the following power output steps:
1kW, 2kW, 4kW, 6kW, 8kW, 10kW, 12kW, 14kW, 16kW, 18kW, 20kW, 22kW, 24kW
This boiler can be set to either 12 kW, 16 kW, 20 kW, or 24 kW, and it will ramp up and down the above modulation scale depending on what the heating system demands and reduce running costs.
Suitable for radiators or underfloor heating systems
Compatible for operation with standard radiators or an underfloor heating central heating system, or even both.
Control options
Both our 24kW electric heating boiler models come with an outdoor weather temperature sensor and an indoor room temperature sensor included as standard for weather compensation control.
You can control the boiler via the digital control panel (not touchscreen operation), which has a clear and simple LED display for heating programming and hot water control – or via a standard room thermostat if so desired.
Or option B
Remote operation: with our internet module, you can control your electric boiler from an app on your phone, pad, or computer. This feature allows you to control your central heating system “on the go,”, as they say!
Smart app with Wi-Fi control of our electric boilers from Flexiheat UK
Product Advantages
Heating only or central heating & hot water
Our boilers can be used for heating only or central heating & domestic hot water (DHW). When used with an indirect cylinder (which can be an unvented or an open-vented system), you can provide ample amounts of domestic hot water for your bath or shower, as well as your dishwashing needs. We highly recommend an unvented indirect cylinder, due to the benefits of mains pressure DHW and the flow rate required.
A diagram showing how our electric central heating boiler is connected to a domestic hot water cylinder.
Why is this setup important?
Because you can have two required temperatures – i.e., the heating side of the boiler, which may be running underfloor heating – which needs a maximum temperature of 45°C or so, or if the boiler is compensating the flow temperatures to a radiator system, for example, when the thermostatic radiator valves close – it may have reduced the water flow temperature to 50°C or 60°C – this would not be a high enough temperature to heat the indirect DHW cylinder.
24kW electric combi boiler option
We go into more detail on our 24kW electric combi boiler option on its own dedicated webpage here – electric combi boilers. These are a true 24kW electric combi boilers which require a three phase voltage electrical supply for space heating and DHW production.
A 24kW combi boiler unit will supply a flow rate of 12.8 litres a minute, which is enough to supply a shower or bath at an adequate flow rate.
They do not make a 24kW electric combi boiler in single phase.
More information/prices for all our products
For more information,support,prices,check stock or to purchase or order our cost-effective 12kW electric boiler, then please don’t hesitate to contact our customer sales team on 01202 822221. Please click here for our email contact form. We serve both trade customers and end users. Standard delivery is available through a 2 to 3-day pallet service; however, next-working-day delivery can be arranged subject to the time the order is placed and stock quantity (not for the Isle of Wight,Isle of Man or Northern Ireland).
12kw Electric Boiler – Electric Boilers
/in Products /by flexiheat12kW Electric Boiler – Electric Boilers
Our 12kW electric boiler can be used for central heating and to produce domestic hot water as well, via an indirect cylinder. Whether the central heating system has standard radiators or underfloor heating systems, our electric boilers can do either or even both. The outcome is electric heating for a wet central heating system, with high energy efficiency.
These electric boilers are the ideal solution for properties that lack mains gas supply or have flue requirements that prohibit the use of gas, oil, solid fuel, or electric storage heaters.
All of our 12 kW electric boilers will modulate their output to the heating requirements. This reduces the electricity consumption used and, subsequently, the fuel bills and running costs.
With a 12kW output, these electric boilers can be powered by a single-phase 240-volt electric supply (the most common electric supply in UK homes), or we have a three-phase 400-volt powered option.
If you buy from a supplier or produce your electricity from renewable energy sources—such as wind energy sources or solar electric energy—then your heating and hot water systems can be zero-carbon-rated.
Electric boiler 12kW output
We have two options – the most popular is a system boiler, designated the FHMN3, which is a single phase 240-volt boiler with up to 13.8 kW of heat output.
or
We also can supply the FHM3-designated version with no expansion vessel for open vent heating systems, but a minimum 5-metre head (0.5 bar of pressure) is required for these boilers to work.
Dimensions of the boiler options
FHMN3 (system boiler version) and FHM3 (no expansion vessel – for open vent systems) series electric boiler 2kW to 24kW heat output dimensions detail from Flexiheat UK
Full brochure is here for direct download
M range electric heating boilers brochure from 2kW to 24kW of output Flexiheat UK
Manual for this range is here:
M range electric boilers technical and installation manual 2kW to 24kW from Flexiheat UK
Smart modulating system with high modulation ratio
The modulating electronic control of thses wall mounted electric heating boilers will ramp up and down the power steps or levels to suit the central heating system requirements – be it underfloor heating or radiators – this auto heating regulation process ensures reduced energy consumption, as the boiler matches the heat output to the demand of heating system demands, resulting in lower energy bills for your home heating.
The FHMN3-14 is a 14kW electric system boiler that includes an outdoor sensor, a 5-litre expansion vessel, and PV solar readiness and has an adjustable output range of 6.9kW, 9.2kW, 11.5kW, or 13.8kW heat output, operating on 1 phase/230 volts only.
This 12kW electric heating boiler modulates according to the following power output steps:
0.8kW, 1.5kW, 2.3kW, 3.5kW, 4.6kW, 5.8kW, 6.9kW, 8.1kW, 9.2kW, 10.4kW, 11.5kW, 12.7kW, 13.8kW
This electric boiler can be set to either 6.9 kW, 8.1 kW, 9.2 kW,11.5kW (close enough to 12kW for us) or 13.8 kW heat output, and the boiler will ramp up and down the above modulation scale depending on the heating system’s demands.
Suitable for radiators or underfloor heating systems
Suitable for standard radiators or an under floor heating central heating system, or even both.
Control options
Both our 12 kW electric heating boiler models come with an outdoor weather temperature sensor and an indoor room temperature sensor included as standard for weather compensation control.
You can control the boiler via the digital control panel, which has a clear and simple LED display – for heating programming and hot water control – or via a standard room thermostat if so desired.
Or option B
Remote operation: with our internet module, you can control your electric boiler from an app on your phone, iPad / tablet, or computer. This feature allows you to control your central heating system “on the go,” as they say!
Smart app with Wi-Fi control room thermostat for our electric boilers from Flexiheat UK
Product Advantages
Heating only or central heating & hot water
Our boilers can be used for heating only or central heating & domestic hot water (DHW). When used with an indirect cylinder (which can be an unvented or an open-vented system), you can provide ample amounts of domestic hot water for your bath or shower, as well as your dishwashing needs. We highly recommend an unvented indirect cylinder, due to the benefits of mains pressure DHW.
At 12 kW output, you can’t get a 12 kW electric combi boiler to produce an adequate flow rate or adequate water temperatures, especially in the winter period, when you require warm domestic water the most. A combi boiler model is only really a suitable solution when you have a 3-phase electric power supply, as they require the higher amps to do the job instantaneously.
The solution for an electric combi boiler sized at 15 kW heat output or under is to use a small indirect hot water cylinder, because with a single-phase 240-volt supply, a combi boiler cannot produce enough flow rate to run a bath or shower during the winter when you need domestic hot water the most. Quite simply, a true electric combi boiler that produces water on demand won’t work at 12 kW heat output or below.
A diagram showing how an electric central heating boiler is connected to a Domestic Water Cylinder.
Why is this set up important?
Because you can have two required temperatures – i.e., the heating side of the boiler, which may be running under floor heating – which needs a maximum temperature of 45°C or so, or if the electric boiler is compensating the flow temperatures to a radiator system, for example, when the thermostatic radiator valves close – it may have reduced the flow water temperature output to 50°C or 60°C – this would not be a high enough temperature to heat the indirect DHW cylinder.
Electric combi boiler
We go into more detail on our 12kW electric combi boiler option on its own dedicated webpage. You can’t produce adequate instant hot water; with a true 12kW electric combi boiler, you need to use a 12kW electric system boiler and choose a compatible indirect hot water cylinder (normally a pressurised mains feed), depending on your needs.
More information/prices for all our products
For more information,support,prices,check stock or to purchase or order our cost-effective 12kW electric boiler, then please don’t hesitate to contact our customer sales team on 01202 822221. Please click here for our email contact form. We serve both trade customers and end users. Standard delivery is available through a 2 to 3-day pallet service; however, next-working-day delivery can be arranged depending on the time the order is placed.
6kW Electric boiler
/in Products /by flexiheat6kW Electric boiler
Our 6kW electric boiler model option for central heating, designed for either radiators or underfloor heating systems and/or hot water via an indirect hot water cylinder, is a zero emissions boiler with a maximum efficiency of 100%.
They are ideally suited for small homes, flats, annexes, or even individual underfloor heating systems (radiant floor heating) within existing properties.Being a great alternative heating solution for locations that are not on the mains gas supply.
With no emissions, no chance of carbon monoxide poisoning, a rapid response to the central heating demands, flexible installation, and fewer moving parts, there is a lower chance of an issue occurring.
Our 6 kw electric boiler products are easy to operate, and installation is generally very easy, both time-wise and trouble free work and are 100% energy-efficient for the heating elements.
Single phase electric supply
Our 6kW electric boiler option is generally powered on a 240 Volt single phase electrical supply to power the immersion heaters. When requiring a 6 kW output, the boiler has a rated electrical demand of 26.1 amps on a single phase supply and require a 32 amp breaker.
But this boiler can also be used on a three phase 415 Volt supply as well; in this case, the amps required are 8.7 amps per phase of the three phases
Small electric boiler
Our 6kW electric boiler is small in dimensions, i.e., depth, width and height, and installation in small spaces or locations is possible (remember, no flue system is required for electric boilers). This enables you to choose your preferred installation location within the property (anywhere you can get the cables and pipework to the boiler within the property).
For example, gas or oil boilers must be installed on an external wall, as they require a flue exhaust system / chimney to be installed to vent the products of combustion to the external air.
Boiler dimensions and weights
Boiler Width = 316 mm
Boiler height = 716 mm.
Boiler depth = 235 mm for the electric system boiler option (model FHMN3 – with circulating pump and expansion vessel) or 191 mm for the open vent model (FHM3 designation), with circulating pump and no expansion vessel.
Boiler empty weight = 20.5 kg for the electric system boiler model (MN3) and 15.8 kg for the open-vented version (M3).
FHMN3 (system boiler version – circulating pump and vessel ) and FHM3 (circulating pump but no expansion vessel – for open vent systems) series electric boiler 2kW to 24kW dimensions detail from Flexiheat UK
These electric boiler products come with a 2-year warranty and are designed to work for many years on a wet electric heating system (radiators or underfloor heating) and an indirect water heater. Please note there must be a magnetic dirt filter and air separator installed on the central heating system.
Boiler modulation
This electric system boiler offers settings of 2kW, 4kW, 6kW, or 8kW (technically 7.9kW, but sufficiently close to 8kW for our purposes). The boiler adjusts its output within this modulation range based on the heating system’s requirements.
This electric boiler has the following power output steps:
0.8 kW, 0.9 kW, 0.9 kW, 1.3 kW, 2 kW, 2.6 kW, 3.3 kW, 4 kW, 4.6 kW, 5.3 kW, 6 kW, 6.6 kW, 7.3 kW, 7.9 kW
So when set at 6 kW, the modulation rate is 11:1, which results in close heating load management and matching and results in an accurate match to the heating system demands and added comfort.
The brochure is here for direct download
M range electric heating boilers brochure from 2kW to 24kW of output Flexiheat UK
Manual for this range is here for direct download
M range electric boilers technical and installation manual 2kW to 24kW from Flexiheat UK
Central heating
Our electric boiler will work on either radiators (with or without thermostatic radiator valves) or an underfloor water heating system, with a selectable outlet flow temperature from 20°C to 85°C in range. These products are designed to work with a heating system with a minimum working pressure of 0.5 bar and a maximum of 3 bar. You can control these units with a standard room thermostat or an app-controlled room thermostat and programmer operation.
Domestic hot water solutions
This 6kW electric boiler can also be used in conjunction with an indirect water heater, allowing you to have a complete electric heating system.
Electric combi
You’re not going to get a 6kW electric combi boiler that can produce a suitable or the required hot water flow rate to even satisfy even a toilet tap, let alone a shower or bath. You simply can’t get the power required to heat hot water instantaneously for a 6kW electric combi. Electric combi boilers simply won’t work at this small an kW output.
One installation option is to use a 6kW electric boiler for the central heating in conjunction with an indirect water heater cylinder for the domestic hot water. Like so schematically
A diagram showing how our electric central heating boiler is connected to a domestic hot water cylinder.
Alternatively, one can use only the 6kW electric boiler for central heating, along with a separate direct unvented hot water heater for domestic hot water.We supply a full range of direct unvented cylinders which are detailed here – Direct unvented hot water cylinders
Contact Flexiheat UK
We have the best 6kW electric boiler products in the UK for sealed heating or open-vented systems. Should you require any further assistance or information, wish to check stock or get a price and delivery charges on our electric boiler with 6 kW of output, please click here to contact us via email or call our sales team on 01202 822221. All sales are provided with a vat invoice as standard.
Combi boiler for a large house
/in Products /by flexiheatCombi boiler for a large house
Combi boiler for a large house – natural gas (mains gas supply) or propane gas (LPG) for a central heating system and high hot water demands
Looking for a combi boiler for a large house? Here we go through the issues that you need to consider when selecting the best combi boiler for a large house to suit your requirements. Selecting the correct combi boiler size for any home, is critical, especially when your residence is a large house, with multiple radiators, or an underfloor heating system and multiple bathrooms, it then becomes vitally important if you require a high efficiency and economical boiler with exceptional hot water flow rates then we have the perfect high heating efficiency gas boilers for your large house / home/ property, which can be fired with either natural gas or LPG / Propane gas.
In a nutshell combi boilers heat water for the central heating system and hot water demands,without a storage hot water cylinder. For this reason, they can struggle to cope with high hot water demands of multiple bathrooms properties that you might have in a 4 or 5 bedroom house for example. But we have a solution to this issue with the best combi boilers for a large property -please read on
What are combi boilers, and what do they do ?
Firstly, we need to establish what a combi boiler is. Well, the boiler’s official name is a “combination boiler” – but over the years the word has been shortened just to “combi boiler”. These boilers are now the most popular type of boiler for homes, flats, etc. in the residential market in the UK. A combi boiler not only supplies the heat for the central heating of the home (i.e., central heating system), but also heats the domestic hot water demands instantaneously as a hot water tap is opened.
If you already have a regular boiler installed in your property, that is coupled up with a hot water storage cylinder that requires a cold water tank in the loft space (if the hot water storage cylinder is a vented cylinder), then installing a combi boiler means you no longer need this cold water tank anymore and recover some loft space.
Generally combi boilers need to be more powerful than regular and system boilers to do the same job, as they use a hot water cylinder to store hot water.
Another benefit of a large combi boiler is that the hot water is fed from the mains water supply, eliminating the need for a feed and expansion tank, and thus the water pressure is often higher, resulting in better hot water performance and higher energy efficiency, without the need to store hot water in an unvented cylinder, for example.
These factors make a combination boiler one of the highest efficiency boilers on the market, with an attractive low cost purchasing price, along with the lower installation costs and continual lower running costs than the older type system boilers that were extensively used with hot water cylinders in previous times in larger homes or properties with complex heating systems.
There are two main elements to a combi boiler sizing, which need to be considered when selecting the correct size large house combi boiler –
The Domestic Hot Water performance – This is the hot water that you use to bath, wash or do the dishes/kitchen use – when preparing meals etc., as you’re not storing hot water in a separate hot water tank with a combi boiler, which makes them the most efficient boilers.
We will look at both of these issues and give you the guidance to ensure that you have the best solution for your combi for a larger house or property with multiple bathrooms and high hot water demands.
Combi sizing for large house / homes / properties
The first part is the easier bit, as they say. It doesn’t matter what heat emitters you are using to heat your home, whether it be a radiator system or an underfloor heating system or even a combination of both. The principle of heat loss sizing for your property doesn’t change for conventional boilers or combi boilers, or if they’re gas and oil boilers for your heating requirements.
Basically, the fabric of your home loses heat, depending on how well insulated the building materials used, such as the brickwork, the floor and the roof. This is known as the “U “value of the materials in question.
This” U “value is official expressed as the rate in Watts [W]) at which heat transfers through 1 square metre [m²] of the surface of a buildings material when there is a temperature difference of 1ºC between the internal and external environments.
So, if you have a property built from the late 1990’s onwards then you are safe to use this ready reckoner chart. This ready reckoner table is based on a brick and block cavity wall with mineral wool insulation having a total wall thickness of 312 mm has a “U” value of 0.3 W/mtr. The building regulation from the late 1990’s specify that this “U” value must be achieved, to pass the building regulations.
You need to ensure that you have the total floor area of your home, including the ground level, 1st floor, 2nd floor etc. It is the home’s / properties total floor area you need to calculate.
For example – If your 5 bedroom house or large home has a total floor area of 600 M/2, then you’re going to need a 48 kW Combi boiler (2 x 300 m2 = 2 x 24 kW – thus a 48kW output combi boiler)
If your total floor area is 440 M/2, then you’re going to need a 48 kW Combi (1 x 300 m2 = 24 kW and 1 x 165 M2 = 13.5 Kw –always go up on the chart – you can turn a combi boiler’s power output down , if you have it there , but you can never turn it up , if it doesn’t have the capacity – thus 24kw + 13.5 Kw = 37.5 kW total boiler output
How many radiators ?
Radiators come in various kW outputs. Ultimately, the number of radiators will depend on what is required to cover your property’s kW heating load requirement.
The best combi boiler is a modulating boiler
Our combi boilers for large homes are modulating boilers, which means they will automatically ramp up and down the boiler’s power to suit the central heating (radiator or underfloor) requirements. They are very clever combi boilers these days!
Domestic hot water performance of the boilers
Ok, now for the second part of a large house combi boiler – the domestic hot water performance/sizing – and these days this is the most important factor when selecting the best boiler to suit your requirements.
Hot water flow rates
A standard showerhead typically requires 7 to 8 litres of hot water per minute of water at 40C, while “green band” showerheads that meet the European Water Label’s criteria demand only 6 litres per minute. Think of this standard as an “ErP” rating for hot water bathroom products, taps, etc. for domestic properties.
Standard shower head 7 to 8 litres a minute flow rate
Please be aware that drench showers can have some huge flow rates, from 15 litres to pretty much any flow rate – 30 litres per minute is not uncommon.
Kitchen sink taps—4 to 6 litres per minute.
Sink taps, which are the standard type, have a flow rate of 4 litres per minute.
Basin/cloakroom “spray taps”—2 litres per minute— these water-saving spray taps are very popular now, as they save water and energy requirements.
Bath mixer taps – modern bath taps have an approximate demand rate of 12 litres per minute.
So by adding all your potential hot water outlets and then applying a diversity factor (a factor that not all the hot water outlets will be used at the same time), you can calculate your hot water demand for your large house combi boiler.
Combination boilers for large houses product range
Combination boilers use a plate heat exchanger to heat the domestic hot water up to temperature from the “heating water side of the boiler”. They have benefits in that they only heat the hot water when there are hot water demands; thus, they are a highly efficient boiler, and we do a range of this type of “big combi boiler” up to 100 kW of output.
50kW Combination boiler – the best combi boiler for a 4 bedroom house ?
A 50kW combination boiler – whereby the plate heat exchanger is integral to the casing of the boiler. This boiler is a modulating boiler with a heating power range of 5.29 to 53.40 kW output at 50/30°C flow and return or 4.83 to 49.19 kW at 80/60°C with 20.30 litres/min of domestic hot water with a temperature rise of 35 degrees C (the standard temperature rise for Scotland and Northern Ireland locations in wintertime conditions) or a 23.4 litres/min hot water flow rate with a 30°C temperature rise. This 30°C temperature rise is the standard temperature rise for most of the UK in wintertime conditions.
This boiler which is an “A”-rated boiler for the heating system and hot water.These are fully detailed on this dedicated webpage 50kw combi boilers which shows dimensions, performance etc. This boiler will be the best combi boiler for 4 bed 2 bathroom house in 99% of the time or a four bed house with 1 bathroom, but using a drench shower.
50kW Combi boiler or Combination boiler – gas fired – from Flexiheat UK
If you want the best combi boiler for 4 bed 3 bathroom house, then you’re probably going to need our larger models, detailed below.
Larger output gas combination boilers
We also have a 60 kW, 75 kW, or 100 kW output option for a large house combi boiler which makes these powerful combination boilers especially suitable for even larger homes such as a combi boiler for 5 bedroom house, that usually have larger hot water demands via multiple bathroom or showers, that any gas safe registered engineer can install.With these models, the plate heat exchanger is mounted directly underneath the boiler above the low loss header (picture below).
Gas combi boiler for 4 or 5 bedroom house with multiple bathrooms from Flexiheat UK
DHW heat exchanger
The large house combination boilers come with a DHW plate heat exchanger that is neatly located above the low loss header of the gas boiler.
The 60 kW model, this combination boiler is a modulating boiler with a power range of 6.44 to 62.84 kW heat output at 50/30°C flow and return or 5.75 to 57.82 kW at 80/60°C with 28.83 litres/min of domestic hot water with a temperature rise of 30 degrees C.
These can either be wall-hung boilers or floor-standing boilers when using our frame mounting kit, as seen in the picture above.
The 70 kW model, this combination boiler is a modulating boiler with a power range of 3.87 to 79.35 kW heat output at 50/30°C flow and return or 3.5 to 72.83 kW at 80/60°C with 35 litres/min of domestic hot water with a temperature rise of 30 degrees C.
These can either be wall-hung boilers or floor-standing boilers when using our frame mounting kit, as seen in the picture above.
The 100 kW model – again, this commercial boiler is a modulating boiler with a power range of 5.29 to 106.80 kW heat output at 50/30°C flow and return or 4.83 to 98.37 kW at 80/60°C with 47.28 litres/min of domestic hot water with a temperature rise of 30 degrees C.
These can either be wall-hung boilers or floor-standing boilers when using our frame mounting kit as above in the picture.
Domestic hot water production figures for our large property combination boilers – Flexiheat UK
The 75kW and 100kW large house combi boiler models mentioned above have a modulation ratio of 1:20 for greater efficiency and reduced consumption both in heating and in DHW production, whilt the 60kW has a 1:10 modualtion. Not only do these units have stainless steel heat exchangers as standard, but they actually have two heat exchangers, or boilers, as such within one casing, meaning should one fail, you still have 50% of your duty available to you (the 60kW boiler only has one heat exchanger). Another benefit is that you can service one boiler while the other is working, so there will never be any “downtime” for your heating or hot water systems, which is a great feature!
Cold water mains supply – Why it’s vital
Combination boilers also have a minus point, which really come into factor when trying to fulfil the hot water demands when used in larger homes with multiple bathrooms or many hot water taps.
A combination boiler may struggle to meet high demands for hot water because it draws all of its water supply directly from the mains water supply. An example of this is when multiple hot water taps are turned on in various bathrooms, the kitchen or other rooms within the house; you will often see a dramatic reduction in the water pressure. That’s why the flow rate of the cold water mains should match your potential hot water requirements.
Hot water cylinder ?
This is caused by the combination boiler not having the benefit of a storage hot water tank, which would meet these levels of demand. This situation used to be resolved by using a regular boiler type commonly known as gas system boilers in conjunction with an indirect hot water storage cylinder.
System boiler for a large house
We have a full range of system boilers that are used in conjunction with a hot water storage cylinder / hot water storage tank when the hot water demands of multiple bathrooms require you to store hot water when the hot water outlets demands of multiple bathrooms can’t be satisfied by the cold water mains supply that combination boilers for large houses rely on.
Obviously installation costs are more for a system boiler and an unvented hot water cylinder setup, as they are more complex heating systems with more pipe work required, but high hot water demands sometimes require this.
Control options for the boilers
You can control our combi boilers using the inbuilt LED display control panel.
However
Everyone now wants to be able to control their boiler, when they are out and about, be it travelling or at work or even on a plane – having the facility to turn your boiler on and have the house warm for when you return to it has now become almost standard. Well the good news is that a our combi boilers can do this – they have a control panel called the Cloud Warm which is an “OpenTherm Plus “compatible controller, which means you can control these combi boilers on the go.
Cloud Warm – Wireless Wi-Fi controller – can be app controlled via a phone, iPad or computer.
This means you can make your life simpler and control these combination boilers from either your mobile phone (android or apple) your PC or tablet, from anywhere in the world, as long as you have an internet connection.
What can you do with the App ?
Cloud Warm App – control your boiler on the go !
With the Cloud Warm app, you can manage your home comfort directly from your smartphone or tablet (Android or Apple). With just a touch of your finger, you can set your comfort level; the app allows you to control, regulate, and program all the parameters for managing your heating system.
This function, which can be managed remotely, reduces unnecessary energy consumption and saves money.
Heating engineers
The last point is that all combi boilers with gas fuel types should be installed by a Gas Safe registered engineer, not just a heating engineer, to comply with the regulations and to ensure that the combi boilers are safely and correctly installed.
Hot water cylinder ?
This is caused by the combination boiler not having the benefit of a storage hot water tank, which would meet these levels of demand. This situation used to be resolved by using a regular boiler commonly known as system boilers in conjunction with a hot water storage cylinder.
System boiler for a large house
We have a full range of system boilers that are used in conjunction with a hot water storage cylinder / hot water storage tank when the hot water demands of multiple bathrooms require you to store hot water when the hot water outlets demands of multiple bathrooms can’t be satisfied by the cold water mains supply that the biggest combi boiler relies on.
Obviously installation costs are more for a system boiler and an indirect unvented hot water cylinder setup, as they are more complex heating systems with more pipe work required, but high hot water demands sometimes require this.
What are you waiting for ! Call us, for the best combination boiler for large properties
So should you be looking for a combi boiler for a large 4 bed house or for a 5 bedroom house , with 2 , 3 or even 4 bathrooms , you can now see why our combi boiler is the best option , as the element of some hot water storage , which is as small as possible , and thus saving on wasted energy , but large enough to cope with the hot water requirements of a large home or property, then please don’t hesitate to contact us at Flexiheat UK for the best combi boilers prices, using the contact us email , or alternatively give us a call on 01202 822221. As we believe we have the best combi boilers for large houses for sale on the UK and Irish market.
How efficient are electric boilers?
/in Guides /by flexiheatHow efficient are electric boilers?
How efficient are electric boilers? Well, the answer is at point of use, electric boilers are 100% energy efficient at the immersion heaters, turning all of the electricity they consume into usable heat.
Could you please explain why they are sometimes quoted as being 99% to 100% energy efficient?
Although virtually all the electrical energy consumed is converted directly into heat through resistance heating (similar to a kettle), some argue that the overall efficiency is 99% because the boiler control panel uses a small amount of electricity during operation or standby mode, which does not contribute to heat output.
How do electric and gas boilers compare for energy efficiency?
Alternatives such as gas boilers are not and never will be 100 per cent efficient, not even a condensing gas boiler. A condensing gas boiler with an A+ energy rating will typically have an energy efficiency in the range of 92%–95%.
The heating system return water temperature must be under ≤ 55°C (ideally ≤ 40–50°C) for a gas boiler to condense optimally.
The efficiency of gas boilers older than 25 years can drop below 60% or even lower, as the heat exchanger becomes fouled up (something that doesn’t happen with electric boilers). Low efficiency results in a loss of both energy and wasted money, whilst electric boiler efficiency will always be 100%.
So, are electric boilers more efficient than gas? Yes.
How efficient are electric combi boilers? 100% efficient on the heating side and 99% efficient on the domestic how water side, as no heat exchanger is 100% efficient
Dirty heat exchangers reduce condensation and the efficiency of gas boilers. That’s why they should be serviced annually, as well as to check for a gas leak, carbon monoxide leak, etc.
Ultimately, natural gas, or even LPG (propane) gas, are both derived from fossil fuels.
What is the situation with oil boilers?
A condensing oil boiler, when run with return temperatures lower than ≤ 50°C for full condensing operation (low-temperature operation, e.g., underfloor heating or oversized radiators), is between 92% and 96% energy efficient. But you’re also burning fossil fuels, which have a sulphur content that must be treated to avoid acidic condensate corrosion and ensure the longevity of the boiler.
Electric boiler pros
Electric boilers are 100% efficient on the immersion heaters, regardless of the flow and return temperatures—whether low or high—because the heating element simply draws power and heats water until the thermostat for the central heating system is satisfied.
The system produces no flue gases. There are no combustion losses. No latent heat to recover. No condensation is needed with an electric boiler installation as opposed to gas and oil boilers.
Electric boilers tend to be combined with an indirect unvented cylinder for domestic hot water production; the electric central heating boilers are detailed on this webpage – Electric central heating boilers
and please see this webpage – for the indirect unvented cylinders, for the DHW production.
We also offer a range of electric combi boilers designed for central heating and instant domestic hot water needs, eliminating the requirement for a hot water cylinder; further details can be found on this webpage – Electric combi boilers
Electric boiler running costs
Renewable energy sources such as wind turbines, solar panels, and tidal or hydropower systems can not only reduce your carbon emissions and thus carbon footprint. They can also reduce the electric boiler running costs if you’re generating electricity yourself.
Contact Flexiheat UK
Hopefully the above has answered your “How efficient are electric boilers?” or “are electric boilers efficient?” question; however, should you have any further questions, please don’t hesitate to contact our Flexiheat UK sales team on 01202 822221 or click here for our email contact form.
Dual Immersion Cylinder Range
/in Products /by flexiheatDual immersion cylinder range
A dual immersion cylinder or twin immersion direct cylinder are simply a hot water cylinder with two immersion heaters fitted to the cylinder.
They are often called an economy seven water heater, because the use economy seven off peak electricity to do most of the hot water heating, through the night time period.
Thus these direct hot water cylinders are not powered by a boiler, but with heating elements powered by a suitable electricity source.
Electricty is 100% energy-efficient, unlike an oil or natural gas boiler for example.
Hot water cylinders powered by twin immersions
A twin immersion hot water direct cylinder offers several practical and energy efficient benefits, particularly in UK homes, by using two separate electric heating elements (immersion heaters) positioned at different heights within the cylinder. Here’s a breakdown of the key advantages:
Flexible & efficient heating with a hot water cylinder with two immersion heaters
Ideal for economy 7 or time-of-use cheap electric tariffs
Better Control Over Hot Water Usage
Compatibility with Renewable Energy
Twin immersion cylinder range
Our stainless steel tank twin immersion unvented cylinder range consists of units from 100 Litres to 500 Litres in volume as detailed below.
Hot water cylinders with twin immersion heaters from flexiheat UK
The above chart shows specification details of the below cylinder.
Unvented direct hot water cylinders – Dimensions drawing for 80 Litre to 500 Litre models
Brocure is here for download
Download the Hot water cylinders direct and indirect unvented brochure from Flexiheat UK
Full installation manual is here for download
Flexiheat manual for direct & indirect hot water cylinders
Special specification tanks are also available in many sizes.
Note: Dual immersion hot water cylinder customised products are non-returnable.
Unvented cylinder
Most modern twin immersion cylinders are unvented, providing consistent, high-pressure hot water from the mains supply.
Unvented cylinders are sealed and filled directly from the mains water supply, designed to provide hot water at high pressure.
Dual element immersion heater sizing
As a rough guideline, the typical consumption rates (hot water requirements per person per day) are as follows:
Patented unvented hot water expansion system
The innovative internal hot water expansion mechanism, which employs a venturi valve to keep an air pocket within the stainless steel cylinder, eliminates the need for an external expansion vessel for our dual immersion hot water cylinder range and is space saving.
Our internal air gap and venturi valve system used on our direct unvented hot water cylinders- no external expansion vessel is required and little to no maintenance is required for the unvented hot water system.
Our direct unvented hot water cylinders have an internal air gap and venturi valve technology that requires no expansion vessel and little maintenance.
Without moving parts, this unvented system provides a long product life and minimal operating and lifetime costs.
Internal air gap system for our direct unvented hot water cylinders: no external expansion vessel is needed because this self-sustaining air gap requires little to no maintenance and ensures mains pressure hot water flow throughout the property with our double immersion cylinder range.
Immersion heater
The immersion heating elements are screwed into the female tappings installed on the cylinder.
The 100 to 500 litre electric water heater / unvented direct cylinders are twin immersion cylinders with two 3 kW incoloy immersion heaters for rapid heat recovery as standard.
Additionally, we offer three 3 kW incoloy immersion heaters that may be installed on our 215 litre to 500 litre direct unvented cylinder versions or three 6 kW dual phase immersion heaters that can be wired either single or three phase, for a total power input of 18 kW.
Incoloy immersion elements
Our immersion heaters are high-quality units manufactured of Incoloy 825 stainless steel and equipped with a temperature control thermostat and an energy cutout thermostat.
Power Requirement for immersion heaters
These immersion heaters can be powered by single or three-phase supplies.
For the 3kW heating elements – these are 240 Volt / 1Phase powered and require 13 Amps of power per element.
If you upgrade to the 6kW heating elements – these can be either 1 phase / 240 volt or 3 phase / 415 Volt wired – if on 1 phase these require a supply of 26 Amps per heater, on three phase they require 9 Amps per phase for each element.
Domestic hot water heat up times
Please double these times if using only one of the 3kW immersion heaters i.e. using off peak electricity to heat overnight.
or half these times if using the upgraded 6kW immersion heaters
If you wish to contact us with a question or to find out further information
Should you require further assistance,information,questions on the product or to purchase / order one of our Dual or Twin immersion cylinder range,which are guaranteed for 25 year domestic use against faulty materials of the stainless steel tank ( 5 years guaranteed for commercial use) then please contact our customer sales team on 01202 822221 or click here for our email contact form to send an email
500 Litre Direct Unvented Cylinder
/in Products /by flexiheat500 Litre Direct Unvented Cylinder
Our 500 Litre direct unvented cylinder is built with corrosion-resistant duplex stainless steel and is at an affordable price. This unvented hot water cylinder for mains pressure hot water uses proven technology and quality production to provide high flow rates and a long product life.
Flexiheat UK warranties this 500 Litre stainless steel unvented direct cylinder for 25 years for household use. Hot water cylinders heated by 100% energy-efficient immersion heaters (100% heat transmission) heat bathrooms and showers.
Direct types are utilised when gas or oil is unavailable, a heat pump is unviable, or people desire carbon-free electricity to heat their water.
This electric powered 500 litre unvented hot water storage cylinder is made from stainless steel making them suitable for hard and soft water areas of the UK.
This water heater can be powered PV solar panels (photovoltaics) which produce solar electricity for off grid or carbon free power. An inverter is required for the immersions – to convert DC to AC to power the immersions correctly.
Patented unvented hot water expansion system
The innovative internal hot water expansion mechanism, which employs a venturi valve to keep an air pocket within the stainless steel cylinder, eliminates the need for an external expansion vessel.
Our internal air gap and venturi valve system used on our direct unvented hot water cylinders- no external expansion vessel is required and little to no maintenance is required for the unvented hot water system.
Our direct unvented hot water cylinders have an internal air gap and venturi valve technology that requires no expansion vessel and little maintenance.
Without moving parts, this unvented system provides a long product life and minimal operating and lifetime costs.
Internal air gap system for our direct unvented hot water cylinders: no external expansion vessel is needed because this self-sustaining air gap requires little to no maintenance and ensures mains pressure hot water flow throughout the property regardless of the heat source.
Our direct unvented hot water cylinders use an internal air gap and venturi valve technology to eliminate the need for an expansion vessel and reduce maintenance.
Our 500-litre electric hot water system requires less space, pipes, and plumbing connections, simplifying installation and saving time and money.
What applications is a 500L direct unvented cylinder appropriate for?
500 litre direct unvented hot water cylinders are suitable for 4-bedroom homes with two bathrooms/showers or more or those with a high hot water demand.
However, hot water usage preferences vary.
See our 500L unvented direct cylinder recovery time data below to decide if this electric water heater is best for you.
This 500 Litre volume direct unvented cylinder is a popular seller in this range; however, if you require a higher volume cylinder, please visit the following webpage: direct unvented cylinder range.
Hot water heating and recovery times for a our direct unvented cylinder 500 Litres from Flexiheat UK
High-quality stainless steel 500 Litre direct-pressurised hot water cylinders include 2 x 3kW immersion heaters.
The typical 2 x 3kW immersion heaters in our 500 Litre unvented electric powered direct cylinder provide the following hot water heat-up and recovery rates:
Water heating and recovery times in minutes for our 500 litre unvented direct cylinder.
Our 80 to 500 litre direct unvented hot water cylinders are listed on this page: Unvented Direct Cylinder in Stainless Steel.
Upgraded immersion heater options.
On both the 2 and 3 immersion models, we can increase immersion heater outputs for faster heat recovery.
Three 3 kW immersion electric heaters can be added to this 500-litre direct unvented cylinder for a total of 9 kW and 214 minutes from 10°C to 65°C.
We can supply this 500 Ltr direct unvented cylinder with 3 x 6 kW immersion heaters. These heaters can output 18 kW from a single phase at 230 volts (27 amps per heater) or three phases (9 amps per phase). This method heats 500 litres of water from 10°C to 65°C in 107 minutes.
Since the standard temperature and pressure relief valve is rated for 10kW, we must upgrade it.
Our manufacture tests all unvented hot water cylinders at 5.5 bar and 10 bar.
If you want a bigger output of up to 36 kW for a 500 Litre direct water heater, please consult this webpage: Commercial electric water heater range.
Unvented Direct Cylinder 500 Litres: Features and Benefits.
Unvented cylinders’ internal air gap is automatically supplied by improved Venturi valve technology.
The standard dual immersion cylinder has 2 x 3 kW immersion heaters, which can be increased to 3 × 3 kW or 3 × 6 kW.
Our straight unvented hot water cylinders with inbuilt expansion require no external expansion vessels.
Our integrated expansion mechanism straight unvented hot water cylinders don’t need extra expansion vessels, making installation in tight spaces easier.
Our direct unvented hot water cylinders – having an inbuilt expansion system require no external expansion vessels to be fitted – making installation in tight spaces easy
Dimensions for a 500-litre unvented direct cylinder
Our 500-litre stainless steel direct unvented cylinder has the following dimensions:
Unvented direct hot water cylinders – Dimensions drawing for 80 Litre to 500 Litre models
The dimensions in millimetres for the corrosion-resistant duplex stainless steel 500 Ltr capacity direct unvented cylinder are as follows:
500L direct cylinder with internal expansion dimensions
The full brochure and installation manuals are here (Which cover both the direct models and indirect models ) :
Download the Hot Water cylinders direct and indirect unvented brochure from Flexiheat UK
Download the installation and technical manual for our direct and indirect hot water cylinders.
Unvented Cylinder Certifications for our 500 litre unvented indirect cylinders
Our 500 Ltr direct unvented cylinder has been certified by CE, BBA, and WRAS, independent organisations that ensure hot water heating products are safe and compliant, in addition to ISO, KIWA, and WRC certifications.
Warranty for the 500 Litre Hot Water Cylinder
For domestic use in homes and apartments, our 500 Litre unvented direct cylinders have a 25-year warranty because we trust them. Immersion heaters and control thermostats are insured for one year after purchase, however the stainless steel hot water cylinder is guaranteed for 25 years.
Contact Flexiheat UK
Please contact us at 01202 822221 if you have any queries or use site contact email form for more information or specifics, the current stock situation, or a price on the best 500 litre direct unvented cylinder/500Ltr unvented direct cylinder model on the UK market. We manufacturer these models from high-grade duplex stainless steel, which has a 25-year warranty for residential customers (5 years for commercial use), a low heat loss rating, and WRAS independent approvals.
400 Litre Direct Unvented Cylinder
/in Products /by flexiheat400 Litre Direct Unvented Cylinder
400 litre unvented direct cylinder in stainless steel
Our 400 Litre direct unvented cylinder is built with corrosion-resistant duplex stainless steel and is reasonably priced. This unvented hot water cylinder for mains pressure hot water was created with high flow rates and a long product life in mind, utilising proven technology and a quality manufacturing method.
Flexiheat UK offers a 25-year warranty for household usage on this 400 Litre unvented direct cylinder in stainless steel. These hot water cylinders are heated by 100% energy-efficient immersion heaters (100% heat transfer) and provide water heating for bathrooms and showers.
When gas or oil is unavailable, or a heat pump is unviable or individuals prefer to heat their water with carbon-free electricity, electric water heating is commonly used thus the term direct models.
Patented unvented hot water expansion system
The innovative internal hot water expansion mechanism, which employs a venturi valve to keep an air pocket within the stainless steel cylinder, eliminates the need for an external expansion vessel.
Our internal air gap and venturi valve system used on our direct unvented hot water cylinders- no external expansion vessel is required and little to no maintenance is required for the unvented hot water system.
This unvented system has a long product life because it has no moving parts, lowering operating and lifetime expenses.
Internal air gap system for our direct unvented hot water cylinders: no external expansion vessel is required because this is a self-sustaining air gap in our unvented hot water cylinder range that requires little to no maintenance and ensures mains pressure hot water flow throughout the property regardless of the heat source feeding the unvented hot water cylinder.
Our direct unvented hot water cylinders use an internal air gap and venturi valve technology, which eliminates the need for an external expansion vessel and requires minimal maintenance.
As a result, our 400 litre electric hot water system requires less space, pipes, and plumbing connections, simplifying the installation process and saving installation costs and time.
What applications is a 400L direct unvented cylinder appropriate for?
A basic guideline is that 400 litre direct unvented hot water cylinders are appropriate for larger residences, such as a 4-bedroom house with two bathrooms/showers or more, or for properties with a high need for hot water.
People’s hot water consumption habits, however, can differ from one another.
Please see the recovery time data for our 400L unvented direct cylinder below to determine whether this is the right electric water heater for your requirements.
This 400 Litre volume direct unvented cylinder is a popular seller in this range; however, if you require a higher volume cylinder, please visit the following webpage: direct unvented cylinder range.
Hot water heating and recovery times for a our direct unvented cylinder 400 Litres from Flexiheat UK
Our 400 Litre direct-pressurised hot water cylinders in high-grade stainless steel come standard with 2 x 3kW immersion heaters.
Our 400 Litre unvented electric powered direct cylinder has the following hot water heat-up time and recovery rates with the standard 2 x 3kW immersion heaters installed:
water heating and recovery times in minutes for our 400 litre unvented direct cylinder flexiheat uk
If you need a different size direct unvented hot water cylinder, we have a whole variety from 80 to 500 Litres, which are detailed on this page: Unvented Direct Cylinder in Stainless Steel variety.
Upgraded immersion heater options.
We can upgrade the immersion heaters to higher outputs for faster heat recovery on both the 2 and 3 immersion model options.
This 400-litre direct unvented cylinder can also be equipped with 3 x 3 kW immersion electric heaters, for a total kW output of 9 kW and a recovery time of 180 minutes from 10°C to 65°C (or 3 hours).
If desired, we can deliver this 400 Ltr direct unvented cylinder with 3 x 6 kW immersion heaters. These heaters can be connected to either a single phase at 230 volts (27 amps per heater) or three phases (9 amps per phase), for a total power output of 18 kW. This system heats the water from cold (10°C) to 65°C in 86 minutes for the 400 litres of volume.
We must also change the basic temperature and pressure relief valve to a higher output model, as the normal valve is rated for 10kW of power.
All our unvented hot water cylinders are pressure tested at the factory, with a maximum working pressure of 5.5 bar and a test pressure of 10 bar.
If you want a bigger output of up to 36 kW for a 400 Litre direct water heater, please consult this webpage: Commercial electric water heater range.
Unvented Direct Cylinder 400 Litres: Features and Benefits.
Improved Venturi valve technology automatically supplies the internal air gap of the direct unvented cylinder.
The dual immersion cylinder comes standard with 2 x 3 kW immersion heaters but may be upgraded to 3 × 3 kW or 3 × 6 kW.
Our direct unvented hot water cylinders with an inbuilt expansion system do not require any external expansion vessels to be installed.
Our direct unvented hot water cylinders, which have an integrated expansion mechanism, do not require external expansion vessels to be fitted, making installation in compact places easier.
Our direct unvented hot water cylinders – having an inbuilt expansion system require no external expansion vessels to be fitted – making installation in tight spaces easy
Dimensions for a 400-litre unvented straight cylinder
Our 400-litre stainless steel unvented cylinder has the following dimensions:
Unvented direct hot water cylinders in duplex stainless steel – Dimensions drawing for 80 Litre to 500 Litre models from Flexiheat UK
The dimensions in millimetres for the extremely corrosion-resistant duplex stainless steel 400 Ltr capacity direct unvented cylinder are as follows:
400L direct cylinder with internal expansion dimensions
The full brochure and installation manuals are here (Which cover both the direct models and indirect cylinders/ indirect models ,which have a coil and are powered by a conventional boiler):
Download the Hot Water cylinders direct and indirect unvented brochure from Flexiheat UK
Download the intallation and technical manual for our direct and indirect hot water cylinders.
Approvals for unvented direct cylinders of 400 Litre in capacity
The 400 Ltr direct unvented cylinder we sell has been certified by CE, BBA, and WRAS, which are independent organisations that ensure hot water heating products are safe and comply with regulations, as well as ISO, KIWA, and WRC certifications, demonstrating that our stainless steel direct cylinders are manufactured to high standards.
Warranty for the 400 Litre Hot Water Cylinder
We are so confident in the quality of our 400 Litre unvented direct cylinders that they come with a 25-year warranty for use in residential applications such as homes and apartments. The guarantee covers the stainless steel hot water cylinder for 25 years, while other parts, such as immersion heaters and control thermostats, are covered for one year from the date of purchase.
Contact Flexiheat UK
Please contact us at 01202 822221 if you have any queries or use site contact email form for more information or specifics, the current stock situation, or a price on the best 400 litre direct unvented cylinder/400Ltr unvented direct cylinder models on the UK market. We manufacturer these models from high-grade duplex stainless steel, which has a 25-year warranty for residential customers and trade customers (5 years for commercial use), a low heat loss rating, and WRAS independent approvals.
Renewable LPG – the present and future for Caravan heating & hot water production
/in News /by flexiheatRenewable LPG – the present and future for Caravan heating & hot water production
LPG Gas and why it’s so popular for caravan and park home heating and hot water
Liquified petroleum gas (LPG) is currently the preferred fuel for heating and hot water generation in the caravan and park home sectors due to its accessibility, clean combustion, and immediate heat generation. However, as we strive for a net-zero society, there is concern about the future prospects of this widely used off-grid gas.
LPG, available in portable cylinders or bulk tanks, serves as an on-site, on-demand fuel source for heating applications in static park homes and communal buildings.
The future of LPG gas
With the UK Government’s goal to reduce carbon emissions in all industries and the decreasing trend in oil and natural gas extraction, the LPG manufacturers must identify environmentally friendly alternatives to LPG for the caravan heating and hot water generation sector.
The LPG gas sector is already making significant progress in transitioning to sustainable, low-carbon alternatives.
Revolutionising caravan heating by utilising renewable liquid gases (RLGs)
The LPG sector is dedicated to shifting entirely to renewable sources and has a well-defined plan to do this by 2040.
As the industry focuses on creating low-carbon heating alternatives in accordance with this goal, two types of renewable liquid gases (RLGs) stand out as promising solutions for the caravan heating sector: BioLPG, also known as Biopropane and Renewable DiMethyl-Ether (rDME).
Both BioLPG and rDME provide ecologically sustainable alternatives to regular LPG without compromising performance. BioLPG is a chemical compound that is exactly the same as LPG, whereas rDME is a chemical compound that is comparable to butane and propane. Furthermore, all alternatives are fully compatible with all your current LPG appliances. This implies a reduction in carbon emissions without the inconvenience or extra expense of acquiring new boilers or water heaters.
In addition, it is possible to mix rDME and BioLPG with conventional LPG, enabling a progressive transition over a period of time. This sets them apart from other biofuel alternatives, since they cannot be mixed with the substances they are replacing and also need the added cost of acquiring new appliances.
BioLPG and rDME are classified as a “drop-in” replacements fuel for standard LPG and are derived from a varied combination of sustainable biological sources and methods, such as agricultural or home waste, energy crops, or recycled carbon.
Renewable liquid gases can reduce carbon emissions by up to 90%. They have similar levels of nitrogen oxides (NOx), sulphur oxides (SOx), and particulate matter as traditional LPG, which helps improve air quality.
Lowering environmental impact
These renewable liquid gases serve as a direct substitute for conventional LPG without the need for any modifications. They can be utilised with existing tanks, heating systems, resulting in cost savings for consumers and a low environmental impact.
Suppliers offer readily accessible BioLPG now, which is marketed under certain brand names. Both bioLPG and rDME may be mixed with traditional LPG, allowing consumers who wish to transition to a more environmentally friendly heating fuel solution and convert to these low-carbon gas fuels.
Boilers for static caravans
The most common boilers for static caravans. glamping pods or park homes are combination boilers that do both the heating and domestich hot water requirements. All of our our lpg combi boilers for caravans can be used with the drop in replacement bio LPG gases without any modification to the burner required.