Highest Flow Rate Combi Boiler

8th January 2025/in News /by flexiheat

Highest Flow Rate Combi Boiler ? High domestic hot water flow rate combination boiler

Our high flow rate combi boiler from Flexiheat UK. This 50kW combination boiler is the highest flow rate combi boiler on the UK market, which is a combi boiler for two showers

Combi boiler with highest flow rate – Flexiheat UK

Our 50kW combination boiler is the highest flow rate combi boiler / combi boiler with the highest flow rate (23.4 litres per minute with a temperature rise of 30°C) on the UK market. No other combination boiler comes close to this high flow rate combi boiler, which is available in natural gas or LPG (propane) gas boiler.

With a combination boiler, you’re only heating the cold water up to the normal domestic hot water temperature of 38°C to 40°C on demand, so you save money on your hot water bills, as you’re not heating a hot water cylinder storage up that may not be used in its entirety.

Most combi boilers on the UK market have average hot water capabilities and aren’t suitable for more than one bathroom homes.

Our combination boiler is ideally suited to properties with high flow rate requirements, especially large properties with two showers or more that can be used at the same time.

With exceptional performance, being ErP rated “A” for both heating and hot water, making our boiler the right choice as a new boiler or retrofit replacement replacements especially in larger homes.

Our 50kW combination boiler type is the right boiler for homes or properties with high demands for heating and hot water.

What is a Combi Boiler?

A combi boiler is a type of heating system that provides both a central heating system and a domestic hot water supply in one unit. A combination boiler produces instantaneous hot water on demand.

Combi boilers are ideal for homes or properties with limited space, as they eliminate the need for a separate hot water cylinder and a system boiler, reducing installation costs.

They are also known for their energy efficiency (energy-saving by the fact that your heating domestic hot water on demand when required) and cost-effectiveness.

Our combination boilers are not suitable for an open-vented system like conventional boilers. The system needs to be converted to a sealed system by heating engineers.

There are storage combi boilers on the market, but you don’t need storage combi boilers when you have the hot water requirements fulfilled with a true combination boiler.

Understanding Combi Boiler Flow Rate

What does the term “flow rate” mean?

The amount of hot water that a combi boiler can supply to your hot water outlets (such as taps or showers) in a minute is indicated by its flow rate, i.e.,

Combi boiler flow rate refers to the amount of hot water a boiler can provide in a set timeframe, normally quoted as litres per minute, at a standard temperature rise of 30°C for the domestic hot water from the cold mains water supply.

However, everything is dependent on how quickly your home’s main water supply flows. It will never reach the desired level if your mains flow rate is less than the combi boiler’s flow rate.

Mains water supply pressure will affect the flow rate of a combi boiler.

A combi boiler could achieve a flow rate of 20 litres per minute, for instance. In your home, that equates to 20 litres of hot water per minute. However, the combination boiler will not be able to achieve 20 litres per minute if the mains water supply flow rate is only 10 litres per minute to the property.

A higher flow rate means more hot water can be supplied, making a combi boiler with the highest flow rate suitable for homes, especially larger homes with multiple bathrooms (two or more bathrooms) or high hot water demand.

Factors Affecting Flow Rate

Water flow rate is the volume of water that runs through a pipe, while water pressure is the force that pushes the water through the pipe.

A number of factors influence the flow rate, including:

The mains pressure and mains supply flow rate to the property
The length of the pipe from the cold mains to the home
The diameter of the pipe from the main supply.
The surface characteristics of the pipe (frictional resistance) and the number and angle of any bends in it from the mains to your property.

There is a relationship between water flow rate and water pressure. Flow rate rises with increasing water pressure, and flow rate typically decreases with decreasing water pressure. However, it is possible that a high water pressure might have a low flow rate, and vice versa.

Water pressure affects flow rates, and a more powerful combi boiler can heat water faster, but only if the mains water pressure is sufficient.
A local installer / heating engineer can help determine the water pressure and flow rate in a home.
The number of bathrooms and taps in a home also affects the required domestic hot water flow rate.

How to Check Your Home’s Water Flow Rate

You can perform a simple test to find out the current flow rate in your home by filling an empty measuring container with water and measuring the time it takes to fill it.

Calculate the liters-per-minute flow rate by dividing 60 seconds by the time recorded.

Alternatively, you can use a water flow gauge, also known as a weir gauge or cup, which is a device to measure the flow rate of water.

Choosing the right combi boiler for your properties water heating demands.

How much hot water you require is calculated by your domestic hot water fixtures, i.e., your quantities and types of hot water outlets you need to provide for; generally, how many bathrooms do you need to service? as these have the highest hot water demands.

Standard showers

Standard shower head 7 to 8 litres a minute flow rate

Standard shower heads use 7–8 litres of hot water per minute at a temperature of 38°C to 40°C. Although the newer “green band” shower heads have a demand of 6 litres per minute, these are the current “ErP” (energy-related product) regulations that aim to reduce water consumption and thus save energy.

Drench showers

“Drench” type showers can have extremely high flow rates, ranging from 15 litres per minute to almost any flow rate—30 litres is not unusual, for example.

Bath taps

Standard bath tap mixer type with a flow rate of around 12 litres per minute at full flow

Bath Tap – 12 L/Min Flow

Standard bath taps have a demand rate of around 12 litres per minute, again at 38°C to 40°C in temperature.

Other types of hot water taps

Standard washbasin taps have a flow rate of four litres per minute.

Kitchen sink taps: 4 to 6 litres per minute.

Washroom basin with “spray type taps”—2 litres per minute.

You may calculate your hot water demand by adding all of your prospective hot water outlets and then using a diversity factor (a variable that accounts for the fact that not all of the hot water outlets will be used simultaneously).

Example: You have two bathrooms or more in your large property—let’s call it three bathrooms, each fitted with a standard 7 L/min shower. For all three showers to be running at the same time, you will require 21 litres of domestic hot water flow to satisfy all the showers simultaneously in the winter period.

So can our boiler cope with two or more bathrooms ? – Yes is the straight answer ! as long as you have the mains water flow rates to the home,and you have standard shower heads of 7 of 8 L/min.

Water temperature rise

The required temperature rise directly affects the amount of hot water a combi can produce.Domestic hot water bathing requires a temperature of around 40°C.

You want hot water the most in the winter period; generally, for most of the UK, 10°C is the coldest mains temperature in winter that we experience; however, for Scotland and Northern Ireland, this is 5°C.

Thus the temperature rise that is required for 40°C hot water (standard bathing temperature) is:

30°C for most of the UK – at this rise the boiler will produce – 23.4 L/min of DHW – which is enough hot water for 3 standard showers

35°C for Scotland and Northern Ireland – at this rise the boiler will produce – 20 L/min of DHW – which is enough hot water for 2 standard showers, plus some extra.

Our 50kW gas-fired combi boiler will produce:

Domestic hot water flow rates of our high flow rate combi boiler at various hot water temperature rises from Flexiheat UK

High domestic hot water flow rates from our 50kW gas fired combination boiler – at various temperature rises.

Combination boiler central heating output

The heating side of the combi boiler

A combi boiler also must provide heat for the central heating system, be it a radiator or underfloor heating system, just like a regular or system boiler does. Our 50 kW combi boiler can operate on an 80°C/60°C hot water flow and return temperature for existing high-temperature heating systems, producing a central heating output of 49.19 kW at this flow temperature of 80°C.

Now with wet heating systems to be designed with a maximum flow temperature of 55°C to lower running costs (energy bills) and reduce carbon emissions by running in a condensing mode continuously.When run at 50°C flow temperatures, the boiler will produce 53.40 kW of heat output for the central heating.

Or alternatively, the combi boiler can be used on lower flow temperature heating systems such as underfloor heating, which normally runs between 25°C to 45°C, as our combination boiler comes with a central heating output setting especially for underfloor heating systems, which limits the boiler output to a maximum of 45°C.This is one of the key features of our high hot water flow rate combi boilers.

Larger homes typically have a higher heating load compared to smaller homes. However, the benefit of our 50kW combination boiler is the larger boiler modulation rate, meaning our boiler is a great choice for smaller homes that have more bathrooms than normal or a high demand for hot water, as the heating side of the boiler will ramp down to 4.83kW on an 80/60C or 5.29kW at 50/30C of central heating output, which is exceptional performance—meaning you have the capability of providing hot water for three bathrooms and not an oversized boiler for the heating system, due to our boiler’s modulation rate. This high-output modulation feature makes our gas boiler one of the best combi boilers on the market.

Energy efficiency

Our 50kW unit is one of the best combi boilers on the UK market with

ErP “A” rated energy efficiency for heating and hot water, with up to 108.83% energy efficiency for this high flow rate combi boiler from Flexiheat UK, designed for multiple bathrooms properties.

With a warranty period of 5 years on the heat exchanger, as long as there is a high quality dirt and air separator fitted (it’s a requirement now as part of the building regulations for the UK) to the system and the combi boiler is serviced every year.

System Boiler vs. Combi Boiler

System boilers can offer higher flow rates than combi boilers, but require space for an indirect hot water tank.

System boilers are less affected by mains water flow rates, making them suitable for homes with low water pressure.

Combi boilers are ideal for homes with limited space, but may not be suitable for homes with very high hot water requirements.

Power Showers and Combi Boilers

Combi boilers cannot run power showers, as they require a boiler connected to a hot water cylinder.

Regular boilers are suitable for power showers but may not be as energy-efficient as combi boilers.

Power showers are not compatible with combi boilers because they operate with an in-built pump that needs to be connected to a hot water cylinder.

Contact Flexiheat UK

For the best highest flow rate combi boiler for homes and large properties with high hot water demand.Please contact our sales team on 01202 822221 to get the best deal or simply click on the following to use our site email contact form to get boiler quotes or for any technical boiler type queries.

Boiler low gas pressure

3rd January 2025/in News /by flexiheat

Boiler low gas pressure?

Boiler low gas pressure? Some boilers have problems with not having enough gas pressure. These problems aren’t always dangerous or common, but they can happen, especially in newer heating systems and result in low gas pressure to your boiler.

This is more noticeable when an installer or service worker goes to your home and finds that the gas pressure at the boiler’s intake is not high enough. Because of this, a Combi boiler won’t heat water to the same temperature and flow rate that it was made to do. This problem often surprises homeowners because it can have a big effect on how well their hot water works, especially in the winter when the cold water coming from the mains is colder.

Why it can go wrong with different gas boilers

This problem isn’t as obvious with central heating because it needs less power. Most of the time, central heating systems are more forgiving because they don’t need as much immediate energy as combi boilers do to make hot water.

It’s also not as bad for regular or system heaters that store hot water in a cylinder. Even though it might take a little longer to heat the cylinder, the water temperature will still hit the right amount. In places where gas pressure problems are common, this can make them a safer choice. However, the right gas pressure should always be available.

A drop in gas pressure can cause combi boilers to produce less heat and water that isn’t hot enough, especially those that need higher outputs (30 to 40KW) to heat water right away. Users can be especially annoyed by this drop in performance, since combination boilers are advertised as being able to constantly provide hot water on demand.

How to fix boiler low gas pressure?

When low gas pressure is found, the gas engineer will usually check the gas pressure at the boiler’s inlet test point while it’s running at full capacity. This is a normal troubleshooting step that helps figure out what’s wrong. If the appliance’s inlet pressure isn’t high enough, the gas meter’s input pressure is checked.

If the pressure on the meter isn’t high enough, you should call the network gas supplier. It’s their job to investigate it and make any necessary changes to make sure all homes connected to the gas line have enough pressure. If the meter’s inlet pressure is good, on the other hand, it means that the gas supply pipes to the boiler is probably either too small or partly blocked. When you use Flexiheat UK boilers, the gas valve entry pressure needs to be between 16.5mb and 20mb. If the drop in hot water temperature is new and the boiler and hot water temperature were fine before, you might also want to check any filters that are attached to the boiler’s gas valve input. This can happen, especially if there has been work on the grid.

Gas pressure drop

Most of the time, the gap isn’t dangerous. Of course, the pressure drop would be small—maybe 3 or 4mb—rather than the usual 16.5 to 20mb at the boiler inlet. The operator might see 13 to 14mb. Even though this means the boiler isn’t working as well as it could, it will still work and fire safely.

Conclusion

One important thing for gas engineers to remember is to figure out where the low gas pressure is coming from, whether it’s in the property’s pipes or a problem with the outside gas mains network, and then fix the problem so the system works as it should. This could mean talking to other pros, like gas network engineers, or giving people advice on what system changes they need. Customers need to be told what happens when their gas pressure is low and how to fix it. This helps set realistic goals and makes sure safety standards are met.

Can I fit a waste or multi oil burner to my existing boiler?

2nd January 2025/in News /by flexiheat

Can I fit a waste or multi oil burner to my existing boiler?

Can I fit a waste or multi oil burner to my existing boiler ? by Flexiheat UK

A Kroll KG/UB waste or multi oil burner from Flexiheat UK is a great way to significantly reduce your heating costs. With its ability to burn almost any used oils from waste engine oils and hydraulic oils to used vegetables oils and Bio Diesel. In fact, our range of waste/multi oil burners are so universal that they can also burn 100% rapeseed oil and heating oils. Because of these wonderful advantages, more and more people are looking to replace their existing oil burner with one of our KG/UB waste / multi oil burners.

Also, these burners are open to atmosphere and not a “sealed burner”– so aren’t suitable for being inside a property , as they will give off an “oil smell” – they should be used in an out house or out building as such.

Below, we have set out a variety of questions which should help you decide if a waste / multi oil burner is suitable to fit and work for your existing boiler.

1. Will the KG/UB waste / mutli oil burner fit onto my existing boiler?

Please check the dimensions, especially the dimensions of the “holes of the burner plate” and the “dimension of the burner tube”. If these dimensions correspond to the dimensions of the burner’s flame tube, the burner flange can be connected.

Please check the below paying particular detail to dimensions “E” and “G”. If the burner tube will fit and you can pick up the burner mountings (G) which have a range due to the slotted burner mounting flange

Download technical details of the KG/UB burners

2. The minimum combustion chamber diameter is 180mm – The minimum combustion chamber length must be –

KG/UB20 Burner model = 320 mm

KG/UB55 Burner model= 360 mm

KG/UB70 Burner model = 360 mm

KG/UB100 Burner model = 380 mm

KG/UB150 Burner model= 400 mm

KG/UB200 Burner model = 400 mm

Download “Can I fit a kroll waste multi oil burner to my existing boiler” document

3.Construction of your boilers combustion chamber;-

We have developed and patented our “ZVP” burner tube. This acts like another combustion chamber, within a combustion chamber, ensuring higher efficiency, better combustion, lower flue gas temperatures and longer maintenance periods.

The following picture shows one of our 200kW waste / multi oil burners with our ZVP tube attached

The ZVP burner tube ,which is attached directly to the burner comes with a ceramic mat for combustion chambers with convex rear as standard or a 500mm x 500mm ceramic fiber board for combustion chambers with a vertical rear panel

Download drawing of combustion chamber variants

4. The Kroll waste/multi oil burners range require a compressed air supply.

This is neither a large amount of air (cfm) nor a high pressure (1.5 Bar Maximum). We produce a whisper quiet compressor, which is extremely quiet and compact (roughly the size of a briefcase), this compressor is controlled by the burner, and is only in use when the burner has a demand. You can utilise your own compressor, as long as it meets the requirements of the burner, and you fit a good quality filter, regulator, water trap prior to the burner.

Whisper quiet air compressor for our waste and multi oil burners from Flexiheat UK

Whisper quiet air compressor for our waste / multi oil burners from Flexiheat UK

5. We would recommend that your existing flue system is at least, 4 meters, and includes an open terminal and a draught stabilizer is required. See below drawing of our recommended flue kit that is required.

For more information on our waste / multi oil burner range, please click here Alternatively, please give us a call on 01202 822222 and our dedicated sales team will be happy to offer advice and assistance or just contact us by email by clicking here.

1000 Litre Hot Water Cylinder

7th December 2024/in News /by flexiheat

1000 Litre hot water cylinder / calorifiers

Our 1000 Litre hot water cylinders, with their high levels of insulation for optimum heat retention and large heat exchanger that ensure rapid heat recovery times and outstanding high flow rates for continuous performance during periods of high domestic hot water demand, are the calorifiers to use for commercial properties or commercial premises such as office blocks, leisure centres, schools or health care facilities.

Domestic hot water cylinders

Our 1000 litre domestic hot water cylinder range are of the highest quality and includes indirect models that offer the choice of either a standard size heat exchanger coil or an extra large coil heat exchanger, providing significantly higher performance levels for high demand domestic hot water heating.

You can equip either hot water cylinder option with an immersion heater (electric heating elements) to supplement the heating coil or to provide backup hot water heating.

Our most popular 1000 litre domestic hot water indirect water heater is our extra-large heating coil version designated the “ELC” range. These have outstanding high flow rates and rapid heat recovery times. These are detailed in the following brochure –

ELC Large coil indirect cylinders for heat pumps or high recovery rates brochure – Flexiheat UK

When the heat source is heating water at 80°C/60°C flow and return temperatures to the tank, and a flow rate of 9.3 m3/h our 1,000 Litre nominal (900 Liters actual) indirect water heater will produce an abundant and powerful supply of 216 KW of heat delivered.

Indirect hot water storage calorifiers

Our 1000 litre indirect hot water cylinder is simple to install and is the perfect solution for almost any location without compromising performance.

They can be used on unvented DHW systems (cold water mains fed) by a supplied external expansion vessel to take up the heated water expansion, making them unvented cylinders or an open vented domestic hot water system.We recommend our stainless steel version for open vented DHW systems.

Air source heat pumps hot water cylinder

For more demanding applications, such as domestic hot water heating with heat pumps, you generally need to use our extra large coil high performance heat exchanger indirect models to ensure you can get the performance required from the hot water cylinder.

Often, you will need to install an immersion heater to the 1000l hot water cylinder, as heat pump flow rates typically reach only 55 degrees C, which is insufficient to raise the hot water temperature above the 60 degrees C required for anti-Legionella purposes, as domestic hot potable water needs to be stored at least at this temperature in domestic hot water cylinders to prevent legionella.

Gas Boiler or Oil Boiler

A gas boiler can provide an abundant and powerful supply of hot water flow to the hot water cylinder heating coil at temperatures of 80°C or so; it is the same for an oil boiler. The higher the hot water temperature, the better the performance of the 1000 litre hot water tank.

Solar water heating

A solar thermal hot water system can also be used as a heat source to power this 1000 litre hot water tank.

Immersion heater options for our 1000l hot water cylinder

We have a full range of various kW output immersion heaters manufactured in stainless steel with a control thermostat to either provide top-up or backup water heating to the hot water system.

The larger the immersion heater, the faster the domestic water will heat.

Insulation on the 1000 Litre domestic hot water cylinder

These 1000 litre hot water tanks with an indirect heating coil are compliant with the ErP regulations for energy efficiency for heat retention, with an ErP “C” energy efficiency rating or above for this hot water storage unit.

Cathodic protection

Our glass lined 1000L hot water cylinder comes supplied with a sacrificial anode as standard; this can be upgraded to a high performance permanent electronic anode on all capacities of this hot water cylinder range with outstanding high flow rates.

We have a stainless steel option for a 1000 litre hot water tank. Our 316-grade stainless steel tanks do not require cathodic protection as standard as they have the best corrosion resistance.

Contact Flexiheat UK

For more details, check stock, lead time, delivery, price, or purchase our 1000 Litre hot water cylinder, as we sell our competitively priced 1000l water heater directly. Please contact our sales team at 01202 822221 or use our site email contact form.

250 Litre Indirect Unvented Cylinder

19th October 2024/in News /by flexiheat

250 Litre Indirect Unvented Cylinder

Our 250 litre indirect unvented cylinder is the best and competitively priced cylinder on the UK market, manufactured in stainless steel with proven technology and quality manufacturing with the capacity to supply mains pressure hot water for your bathroom, shower, wet rooms, and kitchen tap hot water demands in domestic properties.

This indirect unvented cylinder is “indirect,” meaning that the cylinder has a coil within the inner cylinder, which needs to be connected and fed by a boiler, be it gas or oil. Being an unvented cylinder, you cannot use solid fuel boilers as the heat source. You must use a vented cylinder for solid fuel.

Our 250 Litre indirect unvented cylinder does not require an external expansion vessel, as it uses a patented self-sustaining internal air gap within the cylinder to account for the hot water expansion pressure that requires minimum to no maintenance.

Unvented domestic hot water self-sustaining expansion system, so no external expansion vessel is required for our unvented hot water cylinders – Flexiheat UK

What is an unvented indirect cylinder?

An unvented hot water cylinder receives its water supply directly from the main water system, allowing it to produce hot water at a significantly higher pressure than a traditional vented cylinder due to its pressurization.

An indirect unvented cylinder is a type of hot water cylinder that uses a primary coil to heat water indirectly, providing a safe and efficient hot water supply.

Indirect unvented cylinders are designed to work with a boiler as a heat source, providing a reliable and efficient domestic hot water supply.

What hot water demands is a 250L indirect hot water cylinder suitable for ?

The overall amount of hot water used is also greatly influenced by personal behaviours. The amount of hot water used by two houses of the same size might range greatly, with one household needing twice as much as the other.

Understanding peak demands and making sure you have the ideal ratio of cylinder capacity to re-heat times are the most important factors.

As a general guideline, use the following average consumption values for hot water requirements per person per day:

• Low Consumption = 20–30 litres

• Average consumption = 30–50 litres.

• High consumption: 50–70 litres

source – hotwater.org.uk

As a good rule of thumb,a 3 Bedroom + 2 Baths/Shower house should use a 250l unvented indirect cylinder.

Although if the household is a high-water user, then you should look at the next size up cylinder, our 300 Litre unvented indirect cylinder, which are detailed on this webpage – 300 litre indirect unvented cylinder

Key features and benefits

The cylinder is made from highly corrosion resistant duplex stainless, ensuring a long product life and minimal maintenance.
Note – No sacrificial anode is required for a stainless steel unvented cylinder.
Our units are manufactured and certified in accordance with the following approvals – BBA, CE, KIWA, ISO, NSF WRC and WRAS independent approvals.
Quality manufacturing and proven technologies at a competitive price.
We use a stainless steel indirect heating coil (heat exchanger) to speed up heat recovery,minimize heat loss and enabling high flow rates
We use 60mm insulation to reduce heat loss – we use reduce heat loss manufactured factory-injected polyurethane foam insulation bonded onto out highly corrosion resistant duplex stainless steel tank on our 250 Litre cylinder to minimise heat loss and running costs.This high grade insulation is HCFC/CFC free (ODP=0, GWP=1).
Minimal heat loss: Because these units have an ErP rating, they lose less heat, which is better for the environment.
Fitted with a 3kW immersion heater as standard. This immersion heater is made form Incoloy for long durability.
The pressure relief valve ensures a safe and efficient operation of these stainless steel indirect water heaters.
It offers high flow rates for showers and baths in both residential and commercial settings at a maximum inlet pressure of 3.5 Bar, eliminating the requirement for a booster pump.

Our 250 litre indirect unvented hot water cylinders are manufactured from duplex stainless steel and thus don’t require a sacrificial anode, which results in less maintenance time and costs for our 250 litre indirect unvented cylinders.

Our indirect unvented cylinder range allows for installation in smaller spaces because it doesn’t require an external expansion vessel. On the left is our indirect unvented cylinder with no expansion vessel installed, and on the right is an indirect cylinder with an external expansion vessel system, which requires a lot more space for the associated pipework and connections.

Hot water cylinder detail for our 250 Litre unvented indirect cylinder

First we have the basic dimensions of our indirect unvented cylinder 250 Litres in capacity.

Our indirect hot water heater dimensions diagram

Heat up times, recovery times, and weights of our 250L indirect hot water cylinder—unvented model.

Download the –Indirect and direct hot water cylinders in stainless steel brochure from Flexiheat UK

Download the – Installation and maintenance manual for Flexiheat UK indirect and direct hot water cylinders

Hi flow rate 250L indirect unvented cylinder option

We can also supply a 250l indirect unvented cylinder yo enabling high flow rates for larger domestic and commercial water heating demands; this option benefits from 28mm pipe connections and 28mm venturi valve rather than the standard 22 mm pipe connections and 22mm venturi.

Standard indirect hot water cylinder unvented components supplied

Temperature/Pressure Safety Relief Valve: set at 90°C and 7 bar pressure (factory fitted to the indirect unvented cylinder)
The combination (control) valve consists of a line strainer, a non-return (check) valve, a pressure reducing valve, and an expansion relief valve. Supplied lose to be fitted to the incoming cold water mains pipework to reduce the maximum inlet pressure to 3.5 Bar.
3kW Incoloy (a better material than stainless steel) immersion heater, which is single-phase 240 Volt powered, incorporating a control thermostat and re-settable safety cut-out with wras independent approvals. For back up hot water heating or a cheap economy electric power system.
We have the option to upgrade the immersion heater to a 6kW version on this indirect unvented cylinder, which can be powered by either 1 phase or a 3 phase electric power supply
The energy cut out thermostat is set to operate at 82°C (+/-5°C).
Motorised valve to cut the heat source plumbing to the cylinders in the event of a high temperature cut out activation.

Warranty of our indirect unvented cylinder

Because this 250L indirect unvented hot water cylinder is manufactured in duplex high quality stainless steel, which is highly corrosion-resistant.

The hot water cylinder comes with a 25-year guarantee when used in a domestic water heating application (standard household use). If used in a commercial water heating application, then the warranty is reduced to a 5 years.

G3 unvented indirect cylinder installation regulations

Section G3 of the Building Regulations (England and Wales) covers our indirect unvented cylinder range, along with Technical Standard P3 (for Scotland) and Building Regulation P5 (for Northern Ireland). Compliance can be achieved through a Competent Person Self Certification Scheme, where a heating engineer with the Unvented G3 Certificate possesses the necessary knowledge and skills to install and maintain unvented hot water storage systems, or by notifying the local authority building control department of the installation.

Do not try to install or service an unvented cylinder unless you have the necessary certificate or qualifications. An unvented hot water cylinder can explode if not correctly fitted with all of the safety systems that they require.

Installation and maintenance considerations

Ensure the cylinder is installed by a qualified professional and follow the manufacturer installation requirements, with the tundish positioned for occupant visibility and away from electrical devices.

Regularly check and service the pressure relief valve in line with the servicing instructions.

To prevent hot water limescale buildup within the cylinder, especially in hard water areas, consider adding a scale defender.

Water hardness map of the UK and Ireland – a lot of the country is Hard to Very hard in terms of calcium levels, which effects scale potential.

Contact us

For more details, check stock, lead time,delivery,price or to purchase our 250 litre indirect unvented cylinder, as we sell direct our competitively priced cylinder,which is made in the United Kingdom from duplex stainless steel with quality manufacturing methods and a manufacturer 25 year warranty (for domestic use). Please contact our sales team on 01202 822221 or use our site email contact form.

300 Litre Indirect Unvented Cylinder

18th October 2024/in News /by flexiheat

300 Litre Indirect Unvented Cylinder

Our 300 litre indirect unvented cylinder is the best on the UK market, manufactured in stainless steel with proven technology and quality manufacturing with the capacity to supply plenty of domestic hot water for your bathroom, shower, wet rooms, and kitchen hot water tap requirements.

This indirect unvented cylinder is “indirect,” meaning that the cylinder has a coil within the inner cylinder, which needs to be fed by a boiler, be it gas or oil. Being an unvented cylinder, you cannot use solid fuel boilers as the heat source. You must use a vented cylinder for solid fuel.

Our 300l indirect unvented cylinder does not require an external expansion vessel, as it uses a patented self-sustaining internal air gap within the cylinder to account for the hot water expansion pressure that requires minimum to no maintenance.

Unvented domestic hot water self-sustaining expansion system, so no external expansion vessel is required for our unvented hot water cylinders – Flexiheat UK

What is an indirect unvented cylinder?

An indirect unvented cylinder is a type of hot water cylinder that uses a primary coil to heat water indirectly, providing a safe and efficient hot water supply.

Indirect unvented cylinders are designed to work with a boiler or heat source, providing a reliable and efficient domestic hot water supply.

What is a 300L indirect hot water cylinder suitable for ?

Understanding peak demands and making sure you have the ideal ratio of cylinder capacity to re-heat times are the most important factors.

As a general guideline, use the following average consumption values for hot water requirements per person per day:

• Low Consumption = 20–30 litres

• Average consumption = 30–50 litres.

• High consumption: 50–70 litres

source – hotwater.org.uk

As a good rule of thumb,a 4 bedrooms + 2 bathrooms/shower house should use a 300l unvented indirect cylinder.

If the property is on the lower scale of DHW usage, then you may be able to use a 250 Litre unvented indirect cylinder, please see our dedicated webpage on this size of hot water cylinder – 250 Litre Indirect Unvented Cylinder

Key features and benefits

The cylinder is made of high-grade stainless steel, ensuring a long product life and minimal maintenance.
No sacrificial anode is required for a stainless steel unvented cylinder.
Our units are manufactured and certified in accordance with the following approvals – BBA, CE, WRAS, KIWA, ISO, WRC.
Quality manufacturing and proven technologies at a competitive price.
We use a stainless steel indirect heating coil (heat exchanger) to speed up heat recovery and minimize heat loss.
We use 60mm of environmentally friendly factory-injected polyurethane foam insulation on our 300 Litre cylinder to minimise heat loss and running costs.This high grade insulation is HCFC/CFC free (ODP=0, GWP=1).
Minimal heat loss: Because these units have an ErP rating, they lose less heat, which is better for the environment.
The pressure relief valve ensures a safe and efficient operation of these stainless steel indirect water heaters.
It offers high flow rates for showers and baths in both residential and commercial settings, eliminating the requirement for a booster pump.

Our 300 litre indirect unvented hot water cylinders are manufactured from duplex stainless steel and thus don’t require a sacrificial anode, which results in less maintenance time and costs for our 300 litre indirect unvented cylinders.

In our own review – less space and easier installation

Hot water cylinder detail for our 300-litre indirect model

First we have the basic dimensions of our indirect unvented cylinder 300 Litres in capacity.

Dimension diagram of our Indirect hot water cylinders in stainless steel with internal expansion system from 80 Litres to 500 Litres from Flexiheat UK

Our indirect hot water heater dimensions diagram

Dimensions

Heat up times, recovery times, and weights of our 300L indirect hot water cylinder—unvented model.

300L unvented indirect hot water cylinder technical data coil size and recovery rates from Flexiheat UK

Technical detail showing the heat recovery times, kW output rating of the heat exchanger coil at 80C flow of our 300 Litre indirect hot water cylinder.

Download the Indirect and direct hot water cylinders in stainless steel brochure

Download the Installation and maintenance manual for indirect and direct hot water cylinders

Hi flow rate 300L indirect unvented cylinder option

We can also supply a 300l indirect range for high flow rates for larger domestic and commercial water heating demands; this option has 28 mm pipe connections and 28mm venturi valve rather than the standard 22 mm pipe connections and 22mm venturi valve. The stock sku for this is unit 300L Hi-Flo stainless steel indirect unvented cylinder and it has the same primary coil rating as the standard unit.

Standard indirect hot water cylinder unvented components supplied

Temperature/Pressure Safety Relief Valve: set at 90°C and 7 bar pressure (factory fitted to the indirect unvented cylinder)
The combination (control) valve consists of a line strainer, a non-return (check) valve, a pressure reducing valve, and an expansion relief valve. Supplied lose to be fitted to the incoming cold water mains pipework.
3kW Incoloy (a better material than stainless steel) immersion heater, which is single-phase 240 Volt powered, incorporating a control thermostat and re-settable safety cut-out. For back up hot water heating or a cheap economy electric power system.
We have the option to upgrade the immersion heater to a 6kW version on this indirect unvented cylinder, which can be powered by either 1 phase or a 3 phase power supply
The thermal cut-out is set to operate at 82°C (+/-5°C).
Motorised valve to cut the heat source plumbing to the cylinders in the event of a high temperature cut out activation.

Warranty of our indirect unvented cylinder

Because this 300L indirect unvented hot water cylinder is manufactured in duplex high quality stainless steel, which is highly corrosion-resistant.

G3 unvented indirect cylinder installation regulations

Do not try to install an indirect unvented cylinder unless you have the necessary certificate or qualifications. An unvented hot water cylinder can explode if not correctly fitted with all of the safety systems that they require.

Installation and maintenance considerations

Regularly check and maintain the pressure relief valve to the manufacturer’s requirements.

To prevent hot water limescale buildup within the cylinder, especially in hard water areas, consider adding a scale defender.

Contact us

For more details, check stock or purchase our 300 litre indirect unvented cylinder, which is made in the United Kingdom from duplex stainless steel with quality manufacturing methods and a manufacturer 25 year warranty (for domestic use). Please contact our sales team on 01202 822221 or use our email contact form.

Main multipoint FF water heater

22nd September 2024/in News /by flexiheat

Main Multipoint FF Water Heater

If you are looking for a Main multipoint FF water heater, then the bad news is that these gas fired water heaters are no longer available, whether it was the standard model, which was obsolete in 2018, or the main multipoint FF water heater ERP model, which was discontinued around 2019, as this “Main water heater” couldn’t meet the lower NOx levels that were required to meet environmental legislation to reduce harmful emissions to help prevent global warming.

This was also the same for the Main Medway Super water heater and Main Mersey Super water heater, which are no longer available as they are discontinued too.

Sometimes the unit was referred to as a main multipoint ff boiler, in that the unit was a “hot water boiler”. The correct terminology is actually a “hot water heater,” as it produces domestic-quality warm water for bathing, washing, and other uses, rather than heating your radiators or underfloor in a central heating system.

But the good news is that we have a replacement for the main multipoint ff water heater that we stock on the shelf for immediate delivery in both natural gas or LPG gas powered options.

Our replacement unit, designated the “SF14”, is very similar in size to the old main multipoint ff water heater, so there should be no issues fitting the water heater as a replacement, and it also has electronic ignition, thus no pilot light or pilot flame to run which the main multipoint ff gas water heater had , and this saves using gas unnecessary.

The Main Multipoint FF Gas Water Heater’s Design and Features

The Main Multipoint FF Water Heater was a modern room-sealed design, eliminating the need for a separate hot water storage cylinder, as the main multipoint FF water heater was an instantaneous water heater.
The main multipoint ff gas water heater were designed for hot water on demand 24 hours a day, with a sleek and compact design.
The Main Multipoint FF Water Heater had a gas ignition system that only ignited on demand for hot water, reducing energy costs and environmental impact.
These tankless water heaters came with a user-selectable thermostatic temperature control dial and a white finish.

Technical specifications and performance of the main multipoint FF water heater compared to the SF14 water heater replacement

The Main Multipoint FF Water Heater had a maximum nominal heat output of 24.5 kW and produced hot water flow rates that varied with temperature rise.

The SF14 water heater also has a maximum heat output of 24.5 kW.

Hot water performance

The main multipoint FF instantaneous water heater delivered warm water in the following manner:

Our replacement water heater, the SF14 water heating delivery performance is:

Water heater dimensions

The main multipoint FF boiler measured the following dimensions:

Main multipoint ff water heater dimensions

The SF14 tankless water heaters dimensions are:

SF14 on demand water heater dimensions Flexiheat UK

SF14 tankless water heaters dimensions

The Main Multipoint FF Water Heater was only available in natural gas. Our SF14 is available in both natural gas and propane gas (LPG) versions, with the LPG version fuelled by either a 47 kg propane tank or cylinder, or alternatively by a bulk storage propane tank.

The unit had a high-quality design and construction, with a focus on reliability and performance.

The Main Multipoint FF Water Heater was designed to meet the required efficiency levels and reduce energy bills at the time of manufacture.

SF14 Product benefits and features

The highest quality wet chamber copper heat exchanger prevents thermal inertia and features large 16 mm diameter waterways, resulting in very low pressure drops, reduced clogging risks, increased thermal efficiency, and easier cleaning.
The NOx emissions are extremely low, with a maximum of 50 mg/kWh. The main multipoint FF water heater had a NOx level of 184 mg/kWh for comparison.
Modern room-sealed design – so no air vent required in the room.
Various flue pipe configurations – Co-axial, twin pipe flue systems etc.
East accessibility for maintenance and installation.
Self-diagnostic electronic board;
Overheat protection device.
There is a possibility of integration with other renewable energy sources, such as solar water heating.
Degree of electrical protection: IPX4D.

This unit is also a Main Medway Super replacement, with the main medway multipoint water heater only being available in natural gas.

And also a Main Mersey Super replacement as well.

The full manual for the SF14 water heater can be downloaded here directly.

Download the SF14 Low NOx gas fired instantaneous water heater manual – Flexiheat UK

Support and maintenance

It is mandatory to have gas engineers (a qualified gas safe engineer by law) check the gas supply inlet pressure or burner pressure to ensure the correct rate of gas at install and service times. To find a gas safe heating engineer or plumber close to you, please use the following website: Gas safe register

Homeowners and plumbers or a tradesperson without the gas safe plumbing qualification must not attempt to replace parts or service gas water heaters; it is against the law.

Some spare parts are still available for the Main Multipoint FF Water Heater, including the gas isolation valve kit and thermocouple kit, but stock is diminishing and will run out at some point soon.

Flexiheat UK keeps stock of the Main Multipoint FF Water Heater replacement and offers expert advice and support in the event of any questions or concerns.

Contact Flexiheat UK

If you require further information or advice on our hot water product heating solutions, stock availability, delivery times, trade cost prices, or to order a replacement for the Main multipoint BF water heater /main multipoint ff gas water heater, please use the contact us form on our website. Alternatively, you can call our customer service team experts at 01202 822221.

Commercial instantaneous water heater options

9th September 2024/in News /by flexiheat

Commercial instantaneous water heater options for reliable commercial water heating solutions

Commercial instantaneous water heaters,are often called commercial tankless water heaters or commercal on demand water heaters as they provide domestic hot water , without storage on demand for commercial premises in an energy efficient manner.

By far the most popular type of tankless water heaters for large communal residential and commercial applications, are gas fired units due to the output you can achieve from a relatively small gas pipe size.

Flexiheat UK offer instantaneous water heaters with power ratings of up to 200kW in single units and power ratings of up to 400kW in a cascade on demand water heaters configuration.

Typical applications for these instant water heaters include hotels, gyms, healthcare,process, bars, restaurants, brewing, food production, and farming which require a consistent supply of heated water.

Benefits of Instantaneous Commercial Water Heaters

Provide a reliable and energy efficient hot water supply for commercial premises.
Instantaneous water heaters reduce operating costs and environmental impact with energy-efficient technology
Increase customer satisfaction with a consistent hot water flow with precise temperature control
Lare power ratings / Outputs – suitable for various commercial hot water heating applications, including restaurants, hotels, and hospitals
Cost effective / operating costs – The energy efficiency of instantaneous water heaters can be 24%–34% higher than that of traditional storage tank water heaters.Source Energy.gov
When combined with other heating systems, a commercial water heater, in particular instantaneous water heaters, provides a comprehensive solution.
This commercial on demand hot water heater range can provide hot water in very large volumes in an energy efficient manner for any commercial premises or to heat water for a process application.
With an instant water heater / instant hot water heaters, you only heat water when required with high energy efficiency which reduces the energy consumption and energy bills for your hot water system.

Types of Commercial Water Heaters

Tankless water heaters: provide hot water on demand without the need for a storage tank

Instantaneous water heaters: heat water as it flows through the unit, providing a continuous hot water supply

The two types of water heaters mentioned above are identical. It’s just terminology; they are both commercial instantaneous hot water heaters.

Electric models: offer slightly greater energy efficiency and are only really suitable for smaller commercial demands due to the requirements of a 3-phase power supply and the Amps required to heat water.Also operating costs are more for electric powered water heaters.

Gas water heaters:are the most popular and cost-effective option for commercial water heaters/ instantaneous water heaters.

Product Selection and Recommendation

Collect information about your commercial application, including hot water heating demands and power requirements (especially for electric models)
Consider the specific needs of your commercial water heating demands when selecting a water heater

Our commercial tankless water heaters options

When a commercial instant water heater,tankless water heater or on demand water heaters have a kW rating of 50 kW or above for gas-fired units, we consider them a commercial water heater.

First we have our 50kW commercial tankless hot water heater

This commercial instant water heater benefits from a stainless steel heat exchanger featuring large 28-mm single-piece coils that provide very low pressure drops, less chance of clogging, more thermal efficiency, and easier cleaning.

This 50kW commercial instantaneous hot water heater features an inbuilt pump, which can be switched on or off depending on your system requirements, i.e., straight through on demand water heating or DHW recirculation heating system.

Internal picture of our 50kW commercial tankless hot water heater with stainless steel heat exchanger and inbuilt recirculation pump that allows a DHW recirculation system for instant hot water at the taps / showers etc.

Hot water performance i.e. flow rate of our gas fired 50kW commercial tankless hot water heater, at various temperature rises- shown as Delta T i.e. “Δt ”

Water Temperature Rise	Δt 20	Δt 25	Δt 30	Δt 35	Δt 40	Δt 50	Δt 60	Δt 75	Flow rate
SFK50	36.90	29.52	24.60	21.09	18.45	14.76	12.30	9.84	Litres/minute
SFK50	2,214	1,771	1,476	1,265	1,107	886	738	590	Litres/hour

The dairy, brewing, food processing, and agricultural sectors, as well as other applications requiring high-temperature water for washdowns, pasteurization, or process water,and commonly use this 50kW commercial instantaneous water heater / agricultural water heaters as they are capable of producing a maximum water temperature of 85°C.

Features and benifits

The 50kW commercial on demand hot water heater will modulate up to 10:1 for increased efficiency and lower energy consumption.
Producing a steady supply of heated water, as they heat water ‘instantly’ as it flows through these 50 kW gas fired commercial instant hot water heaters
Our commercial gas tankless water heater uses patented advanced burner technologies with a compact design.
This commercial instant water heater has an integrated recirculation pump allowing the choice of direct flow through mode (draw) or a DHW recircualtion mode for immediate DHW supply.

Operating modes of direct or DHW recirculation mode for our 50kW commercial tankless water heaters from Flexiheat UK

Possible operating modes of our 50kW commercial tankless hot water heater – Direct (draw mode) with option of post circulation and DHW recirculation via the inbuilt DHW pump.

Download the SFK50 – 50kW Commercial instantaneous hot water heater manual Flexiheat UK

Please note –

If the commercial gas tankless water heater needs to operate at temperatures higher than 60 °C, the hardness of the water must be less than 150 PPM.

The amount of carbonate, calcium, and magnesium minerals in water is measured to determine its hardness – 75 to 150 ppm is regarded moderately hard for reference.

Also on the other scale, do not soften the water to levels lower than 50 PPM, it turns acidic at these levels and may decrease the instant hot water heater’s lifespan by corroding parts of it.

Larger industrial and commercial instantaneous water heaters

In order to consistently satisfy instantaneous large capacity commercial and industrial domestic hot water (DHW) demands, we developed the “SFKG” family of floor-standing, high-efficiency condensing gas water heaters with a space saving design.These are an industrial tankless hot water heater range with very large domestic hot water heating performance.

instantaneous gas water heaters; gas water heaters in cascade; lpg multipoint water heater; gas fired condensing water heaters; condensing water heater;

Large instantaneous gas water heaters- condensing in cascade in one self-contained floor standing unit ,150kW or 200kW from Flexiheat UK

Instantaneous water heaters – ideal for both new and existing buildings with domestic hot water systems, such as hotels, restaurants, schools, hospitals, apartment buildings, and spas and leisure centres, that require instant water heaters.

High capacity instantaneous DHW systems

A compact single floor-standing gas fired commercial water with either three (150 kW model) or four (200 kW model) load-balanced 50 kW stainless steel heat exchangers within the casing that guarantees even wear along with integrated redundancy as standard making these instant hot water heaters well suited for commercial settings.

A picture of our Industrial tankless hot water heater, gas fired, showing the multiply heat exchangers for redundancy and to ensure reliable domestic hot water heating from Flexiheat UK

SFKG – our Industrial on demand hot water heater range in 150kW or 200kW single units – 400kW in casacde.

Multiple heat exchangers within one water heater casing will consistently ensure operational continuation in the event of maintenance or malfunctions.

With built-in redundancy that ensures service continuity and multiple (three for the 150kW model or four for the 200kW model) integrated heat exchangers providing load balancing for optimum long-life operation.

Designed to provide hot water for both new and existing buildings domestic hot water systems, such as hotels, restaurants, schools, hospitals, apartment buildings, spas, leisure centres, or any other businesses that require high levels of hot water for their customers or process applications such as agricultural water heaters.

Download the SFKG150 and 200kW Gas instantaneous commercial water heaters brochure from Flexiheat UK

Features and benefits

Compact floor-standing configuration instant water heaters which are condensing water heaters.
107.50% energy efficient at full power and 112% energy efficient at minimum power.
Both LPG and natural gas versions are available of these instant water heaters.
High-capacity instantaneous production of domestic hot water for commercial or industrial use.
Multiple stainless steel heat exchangers (the SKFG150 has three and the SFKG200 has four) provide built-in redundancy.
A high-efficiency pre-mix burner provides a large modulation range; the 150kW model has a 30:1 modulation range, and the 200kW model has a 40:1 modulation range.
5 year warranty on the heat exchanger (subject to terms and conditions), 2 year warranty on all other parts for these commercial water heaters.
The heat exchangers’ large 28 mm diameter ensures very low pressure drops, lower risks of clogging, greater thermal efficiency, and greater ease of cleaning.
We recommend softening the water to a maximum hardness of 100 ppm if the total hardness of the water supply exceeds 150 ppm if the water heaters are water heating at a water temperature above 60 °C.
Maximum working pressure 8 bar (10 bar at special request), minimum working pressure 0.5 bar for this range of commercial water heaters.

Industrial instant hot water heater, which is an industrial inline water heater providing energy efficient and cost effective domestic hot water heating for industrial hot water heating systems

Industrial instant hot water heater / Industrial inline water heater providing energy efficient and cost effective domestic hot water heating for industrial hot water heating systems.

150kW Industrial tankless water heater, gas-fired – hot water performance flow rate data – at various Delta T

Water Temperature Rise	Δt 20	Δt 25	Δt 30	Δt 35	Δt 40	Δt 50	Δt 60	Δt 75	Flow rate
SFKG 150	110.19	88.15	73.46	62.96	55.09	44.08	36.73	29.38	Litres/minute
SFKG 150	6,611	5,289	4,408	3,778	3,306	2,645	2,204	1,763	Litres/hour

This 150kW industrial and commercial on demand gas water heater delivers exceptional instant hot water performance. A standard shower head has a flow rate of 7 litres per minute. In the winter, the temperature of the cold water mains is 10 degrees Celsius for the majority of the UK, while the showering temperature is 40 degrees Celsius, resulting in a temperature rise of 30 degrees. This 150kW commercial instantaneous hot water heater will supply 10 showers with continuous hot water if you have the water flow rate and gas supply required.

200kW Industrial tankless water heater, gas-fired – hot water performance flow rate data – at various Delta T

Water Temperature Rise	Δt 20	Δt 25	Δt 30	Δt 35	Δt 40	Δt 50	Δt 60	Δt 75	Flow rate
SFKG 200	146.92	117.53	97.94	83.95	73.46	58.77	48.97	39.18	Litres/minute
SFKG 200	8,815	7,052	5,877	5,037	4,408	3,526	2,938	2,351	Litres/hour

Just to give you an idea of the incredible instant hot water performance of this 200kW industrial and commercial on demand gas water heater. A standard shower head has a flow rate of 7 litres a minute. In the winter the cold-water mains temperature is 10 Degrees C for the majority of the UK, and the showering temperature is 40C, thus a temperature rise of 30C. This 150kW commercial instantaneous hot water heater will supply 14 showers with continuous hot water, if you have the water flow rate and gas supply required.

Residential vs. Commercial Applications

The design of commercial water heaters meets the higher hot water demands of commercial water heating requirements.

Residential water heaters are often not suitable for commercial use due to lower power ratings and flow rates required to heat water in domestic applications.

We provide a comprehensive range of gas on demand water heaters to provide hot water for homes, apartments, and smaller projects. You can find more information about these on our dedicated webpage: instantaneous gas water heaters

Hydrogen ready water heating equipment

We have designed all of our commercial instantaneous hot water heaters to be hydrogen-ready and capable of operating on a 20% hydrogen blend, facilitating a seamless transition to zero-carbon emissions.

Commercial Water Heater Installation and Maintenance

Ensure proper installation by a qualified gas safe heating engineer to ensure safe and efficient operation.
Regular maintenance is necessary to extend the lifespan of any commercial water heaters and prevent costly repairs or downtime.
Consider the installation and maintenance requirements of the commercial water heater, such as clearances, flue system requirements, etc.

Contact us

When you specify and install a Flexiheat energy efficient commercial and industrial on demand water heater, you can be confident that you will be getting the most durable, trouble-free water heater available.

Should you require further assistance or information on our commercial instantaneous water heater range, then please contact our sales team on 01202 822221 or click here for our email contact form.

Chilled Water Buffer Tank Sizing

30th August 2024/in News /by flexiheat

A Chilled Water Buffer Tank Sizing Guide for Optimal System Performance

If you’re looking for the best approach to sizing a chilled water buffer tank or vessel, you’ve most likely seen chillers cycle because the buffer vessel or tank is too small.

Have you ever been annoyed by temperatures that fluctuate as your load changes? As the load decreases, the room’s temperature drops abruptly.

The system fails due to a low temperature fault, necessitating a service call to the location to complete the reset. In addition, there is a possibility of flooding back and oil buildup in the compressor, among other potential issues.

Perhaps your problem was the opposite: going much over budget for an 8,000-liter buffer tank when you only needed half that volume.

Calculating the buffer tank size required for your chilled water system may appear to be a daunting undertaking, but getting chilled water buffer tank sizing right is essential for your chillers and other equipment requirements for your hvac system and customer satisfaction.

The chiller manufacturer should be your first stop, because all chillers can have nuances. Nobody knows their chillers better than they do, so our advice is to contact them first for a recommendation.

When is it appropriate to use a chilled water buffer tank?

A chiller requires a particular system volume to function in low-load mode without cycling.

Cycling can occur in low-load situations, such as when everyone who works leaves the premises at the end of the day.

The building load significantly decreases, necessitating an increase in the system’s volume to avoid cycling and subsequent damage to the chiller.

Identifying scenarios that require a buffer vessel or tank for chilled water

Water chillers require a certain system volume to operate in low-load conditions without cycling.
If the total system volume (TSV) is less than the chiller manufacturer’s requested capacity, a buffer tank is required.

The benefits of using a buffer vessel or tank in chilled water systems

Prevents temperature fluctuations and system cycling.
It ensures optimal chiller performance, improves energy efficiency and prevents potential damage.

Buffer Tank Sizing Fundamentals

Understanding the variables that affect the size of the buffer tank is crucial.

Determine the kW rating of the chiller and the necessary system capacity.
The total system volume (TSV) encompasses the water capacity volume of the chiller, pipe system, and buffer tank.
Flow rates and desired temperature fluctuations.

The formula: calculating buffer tank size accurately

First,the chilled water buffer tank sizing rule of thumb

Chiller manufacturers can differ in their system volume needs; however, four litres per kW seems to be the normal ratio for air conditioning system comfort control applications. Thus, chiller kW x 4 litres = required system capacity (litres).
However, multifunction chillers can be up to 11 liters/kW. This is due to the need to balance the heating and cooling within specific limits, which complicates the system and necessitates the additional volume.

Then the accurate calcualtion is:

Required System Capacity (L) – Total System Volume (L) = Required Buffer Tank Volume (L).

V=N x 60 x Z / 4.18dt

V = total system water content (litres)
N = the chiller’s first capacity step (kW).
Z = the minimum allowable running time (minimum 5 minutes).
dt represents the temperature difference at the minimum part load condition, which is, for example, 2 °C.

This allows the chiller to operate smoothly at low load capacities, and it should provide sufficient thermal storage to offer at least 5 minutes of operation after the unit has stopped running.

The Role of Bypass Valves in Buffer Tank sizing

The positioning of the bypass valve is important; it can’t be too close to the chiller.

To avoid damage from cold water flowing back into the chiller, position the bypass valve far enough away from the chiller.
The valve should be positioned to ensure the volume of water enclosed in that section of pipe meets the specification or minimum volume of water required by the chiller.

How do bypass valves affect the total system volume?

The TSV used in the buffer tank volume calculation should be adjusted based on the length of pipe required for the water to come out of the chiller and return through the bypass.

Avoiding Common Sizing Mistakes

The consequences of undersizing a chilled water buffer tank are significant.

There are temperature fluctuations, system cycling, and potential damage to the chiller.
Adjustments to the BMS and installing additional valves may help temporarily, but they cannot solve these problems.

Strategies for preventing undersizing

Use the correct formula to calculate the required buffer vessel or tank volume.
Consider variables such as flow rates, desired temperature fluctuation, and chiller kW rating.

Choosing the Right Buffer Tank

The process of determining the buffer tank capacity involves taking into account the stabilisation of the system and the actual water level.

Calculate the water required for system stabilisation using the formula:M1 = QT / (C △ T), where Q is the unit’s heating capacity (in KW), T is the defrost time (in seconds), C is the specific heat capacity of water (4.187), and △ T is the maximum allowable drop in water temperature (in °C).
The actual water volume of the system is the sum of the water capacity per meter of the floor heating pipe and the total length of the system pipe, including the water capacity of radiators.

Then look at this webpage for our range of chilled water buffer vessels or tanks and select your appropriate buffer vessel for chilled water

Material considerations, installation guidelines, and maintenance tips

Consider material options such as carbon steel or stainless steel.

Ensure proper installation and maintenance to prevent corrosion and damage.

Regularly inspect and clean the buffer tank to maintain optimal performance.

Electric multipoint water heaters

22nd August 2024/in News /by flexiheat

Electric Multipoint Water Heaters for Instant Hot Water

Electric multipoint water heaters are an excellent solution for supplying hot water to multiple points with an instantaneous water heater.Thus the term “multipoint instantaneous water heater”

Our multi-point electric water heaters have state-of-the-art heating technology, allowing for precise temperature regulation to provide personalised comfort. Typically, our units with a rating output of up to 27 kW come with digital displays and adjustable temperature settings for easy water temperature monitoring and adjustment.

This multipoint instantaneous water heater range is typically used in domestic and commercial applications such as shops, factories, student accommodation, etc., supplying hot water for one outlet or multiple outlets, depending on the flow rate of the shower or taps (sink taps for dishwashing, food preparation, etc. or toilet-type taps) being used.

You will require a three phase power supply to this multipoint instantaneous water heater range – you needs the Amps to heat water on demand.

What is an Instantaneous Electric Water Heater?

An instantaneous electric water heater is a type of water heater that provides hot water on demand, without the need for a storage tank.
A multi point electric water heater heats water instantly, using electricity, and supplies it to various points of use, such as sinks, showers, and basins depending on the flow rates required.
Instantaneous electric water heaters are ideal for residential and commercial applications where water heating is required quickly and efficiently with energy savings compared to storage water heaters.

Benefits of Multipoint Water Heaters

An electric multi point water heater,which is a tankless heater provides hot water on demand, eliminating the need for storage water heaters.
Energy-efficient, as they only heat water when needed.This instantaneous water heater range all have a ErP “A” energy rating.
Lower utility bills because there is no standby heat loss that you have with a storage tank system.
Suitable for multiple points of use, such as sinks, showers, and basins or to provide instant hot water for an appliance such as a dishwasher or washing machine.
Compact design, ideal for compact spaces or remote areas for point of use such as a sink or shower that require instant hot water.
These wall mounted multipoint electric water heaters can be used in commercial water heating settings, such as offices, restaurants,student accommodation and hotels, as well as larger households.

Key features to consider for instantaneous electric water heating

Look for an instantaneous water heater with a suitable power rating (the kW rating) to meet your hot water needs.
Safety features: Ensure the multipoint hot water heater has features such as a high temperature cut out, which is a safety cut out for overheating protection.
Multiple points: Consider a water heater that can supply hot water to multiple hot water outlets / points of use.
Check the flow rate of the multipoint electric water heater to ensure it meets your hot water needs.

Choosing the Right Size and Type

Consider the number of points of use and the flow rate required.

Choose a multi point electric water heater with a suitable power rating (in kW) to meet your instant hot water needs.

Overview of the product – multipoint water heater electric powered, including its features such as wall mounted etc and benefits.

Review of the product’s performance, including its flow rate at your required water temperature increases , the maximum water temperature it can produce, and energy efficiency.

Flow rates for hot water fixtures

Standard shower head: 7 to 8 litres per minute flow rate

Standard shower head 7 to 8 litres a minute of flow @ 40C

A standard shower head requires 7 or 8 litres of hot water per minute, whereas European Water Label “green band” water-saving shower heads require 6 litres per minute. Think of this standard as an “ErP” rating for bathroom products, taps, etc.

Kitchen sink taps: 4 to 6 litres per minute

The “spray taps” for basins and sinks range in capacity from 2 to 4 litres per minute.

Be careful to check the flow rates on your spray taps, as all our instantaneous water heater units require a minimum flow of 2.5 litres per minute to operate.

Modern bath mixer taps have an approximate demand rate of 12 litres per minute.

Please note:

Please be aware that drench showers can have massive flow requirements, ranging from 15 litres to pretty much any flow rate; 30 litres per minute for a drench type shower is not uncommon. For these water heating applications,a large instantaneous water heater will be required or even a direct storage unvented DHW cylinder due to the high volume of water required to feed this type of shower.

Product range

These instant water heaters feature four power ratings or output ranges in a single unit. The 27kW and 36kW electric multipoint water heater, on the other hand, only offers a single power setting.

For instance, you can choose between the 17kW, 18kW, 21kW, or 24kW power outputs on our 17kW to 24kW instantaneous water heater .

This affects the draw-off point flow rate; therefore, at 17 kW, it will produce 8.1 litres; at 24 kW, it will produce 11.6 litres a minute, at the standard temperature rise of 30 °C, for daily use in the winter period, as that’s when you want hot water the most, as you can see in the following data table.

Power output of the instantaneous water heater	9kW to 15kW power rating	17kW to 24kW power rating	27kW	36kW
Energy efficiency class	A	A	A	A
Heat capacity ( power setting options)	9/11/12/15 kW	17/18/21/24 kW	27 kW	36kW
Electrical supply – All require a 3 Phase power supply	400V 3N~	400V 3N~	400V 3N~	400V 3N~
Mains water supply pressure (Bar) min – maximum	1 to 10	1 to 10	1 to 10	1 to 6
Hot water flow rate at Δt=30 in litres per minute	4.3/5.2/5.8/7.2	8.1/8.7/10.1/11.6	13	17.3
Rated current (Amps)	3×13/15.9/17.3/21.7	3×24.6/26/30.3/34.6	3 x 39	3 x 39.9
Dimensions – W x D x H (in mm)	245 x 126 x 440	245 x 126 x 440	245 x 126 x 440	315 x 140 x 492

Please note that our instantaneous water heater range requires a minimum flow rate of 2.5 l/min to start heating the water. The whole multi point electric water heater range will not operate if the flow is lower than this point.

For a given kW output from the hot water heater – as the water temperature increases, the flow rate decreases is the basic rule of physics.

The 9kW to 27kW have a digital display for easy monitoring and precise temperature control.

Digital display on our instantaneous electric water heaters from 9kw to 27kW from Flexiheat UK

The digital display on our 9kW to 27kW instantaneous water heater / multipoint water heater electric powered range

Download the 9kW to 27kW multipoint instantaneous water heater range manual

and our 36kW instantaneous water heater has a tradtional temperature dial and is really suited to commercial settings.

36kW electric instant water heater from Flexiheat UK

36 kW Electric instant water heater – with a manual temperature control dial

Download the 36kW Electric multipoint instantaneous water heater manual

Installation and safety considerations

Make sure a qualified electrician installs the water heater.
Follow the manufacturer’s installation guides and instructions to ensure the warranty.
Ensure the instantaneous water heater is located (wall mounted) in an area with adequate space to service or inspect the water heater and as close as possible to the water outlets being served.
The water heater must not be installed in a site that is exposed to the danger of an explosion and where the temperature might drop below zero C, as the water in the heater will freeze and damage the water heater, which will invalidate the warranty.
Check the water heater’s safety features, such as the high temperature cut out i.e., a safety cut out to prevent overheating.
No pressure relief valve is generally required on an instantaneous water heater unless the water pressure can get above the 10 bar the 9kW to 27kW electric multipoint instantaneous water heater models are rated for.The 36kW electric multipoint instantaneous water heater is rated to a maximum water pressure of 6 bar.
No Expansion vessel is required for an instantaneous water heater / multipoint water heater electric powered, as they supply instant hot water there is no hot water storage to account for unlike tank-type water heaters.

Energy Efficiency and Running Costs

Instantaneous electric water heaters are energy-efficient, as they only heat water when needed they reduce your water heating energy consumption.

Look for a water heater with a high energy efficiency rating- Our electric multipoint instantaneous water heaters have an “A” energy rating.

Consider the running costs of the water heater, including electricity consumption and maintenance costs.

Contact us

Should you require further assistance, check stock (we normally have the units on the shelf for the next working day delivery or select express delivery times i.e. timed, weekend saturday delivery etc), or get prices on our energy-efficient and cost-effective electric multipoint water heaters with accurate factory fitted temperature control and supplying hot water with no standby heat loss, then please call our sales team on 01202 822221 or click here for our email contact form, as we deal with both the public and trade customers.