Combi boiler for a large house

Combi boiler for a large house – natural gas or propane gas

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 gas boilers for your large house / home/ property.

In a nutshell combi boilers heat water for the central heating system and hot water demands, normally without a hot water storage cylinder. For this reason, they can struggle to cope with the hot water demands of multiple bathrooms properties that you might have in a 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 boilers official name is a combination boiler – but over the years this 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 for 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 tanks, 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.

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, which need to be considered when selecting the correct size combi boiler –

1. 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 the boiler has sufficient capacity to heat your large home
2. The Domestic Hot Water performance– This is the hot water that you use to bath, wash or doing the dishes / kitchen use – when preparing meals etc

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.

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, 1^st floor, 2^nd 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

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 ( radiators 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 combi boiler for a large house– the domestic hot water performance / sizing – and this these days is the most important factor when selecting the best boiler to suit your requirements.

Traditional combi 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 is a demand, and we do a range of this type of combi boilers up to 50kW of output which is an “A” rated boiler for the heating system and hot water , these are listed on this webpage 50kw combi boilers

50kW Combi boiler or Combination boiler – gas fired – from Flexiheat UK

But they also have some minus points, 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.

Because a combination boiler draws all of its water supply directly from the mains water supply, these boilers struggle to meet high demands for the hot water. 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.

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.

We’ll we at Flexiheat UK have solved that problem, we basically have a “hybrid combi boiler” or a “combi boiler with an element of storage”, which makes these powerful boilers especially suitable for larger homes, that usually have larger hot water demands via multiple bathroom or showers, that any gas safe registered engineer can install.

Another benefit of having an element of hot water storage is that the larger the property, the longer the hot water pipe runs tend to be, so depending on the property layout you can install a secondary domestic hot water return, which eliminates the delay for the hot water to get to the taps around the home, this also eliminates what is referred to as “hot water dead legs”.

So this brings us to our range, and why our boilers are regarded as the best combi boiler for a large house

We do two models –

the 55 model – which is a combi boiler that modulates its output all the way from 12 to 55 kW for the heating side of the boiler and will produce 54 kW of heating power for the domestic hot water demand

or the largest model – our 65 unit – which is a combi boiler that modulates its output all the way from 13.5 to 65 kW for the heating side of the boiler and will produce 64 kW of heating power for the domestic hot water demand

Each of these boilers are available with a hot water tank in either 60 , 90 or 120 litres of storage , which can handle a domestic water pressure of up to 6 bar ( any more than 3 bar ,and a shower can start to get painful with that pressure , and your taps turn into powerful water jets , often with the water coming out at such a force , that it goes everywhere.

But here is the element which makes the combi boilers the best choice for a large house – the Domestic Hot water performance – it literally is phenomenal, remarkable or exceptional – however you want to call it.

To explain how good it is – here are some stats –

Baths

According to BS6700 a standard bath (1700mm x 700mm) full capacity is around 180 litres to overflow level, but most people fill their bath tubs to around half way to allow for the displacement of water when they get into the bath. So, the actual volume of water used is 100 litres.

The normal bath water temperature is around 40 Degrees C

When you have stored water, this is kept at 60 Degrees C to prevent legionella, which is then blended down with cold water to achieve the 40 Degrees C, at a ratio of 60% hot water and 40% cold water, or 60 litres of hot water and 40 litres of cold water to make up the 100 litres.

Thus, a bath cycle requires 60 litres of hot water, stored at 60 Degrees C

The 60 litre tank, would recover it’s hot water in 6.30 minutes, (which means you can start filling a bath 6 minutes 30 seconds after filling the previous one )  the 90 litre in 6.30 minutes ( one and a half baths ) and the 120 litre unit in 6.30 minutes ( two baths simultaneously )  , which is very impressive domestic hot water performance indeed, as these combi boilers have a hot water priority system.

Showers

The figures are even more impressive for showers –

According to all the data, a standard 5-minute shower approximately 45 litres of water at 40 degrees C, which uses 27 litres of hot water stored at 60 degrees C – with a standard shower head. From this data – our 60-litre hot water storage tank will do 2 shower – simultaneously – the 6 and half minutes later you could go again

Our 90 Litre – 3 showers, again simultaneously – 6 and a half minutes, you can go again

Our 120 Litre – 4 showers with a little spare, again simultaneously – 6 and a half minutes, you can go again

In reality , we would say , that the persons wouldn’t have even come out of the shower room or bathroom, as they need time to dry off , shave , clean their teeth , do their hair etc, before the unvented hot water cylinder has recovered all of the hot water, in this way you could almost say that you have infinite hot water and all at a great water pressures – no limp or poor showers here !

Water Pressure

As a combination boiler draws all of its water supply directly form the mains water supply, they can often struggle to meet high water demands, especially in large properties like a 4 or 5 bedroom house .We have all seen what happens when a person turns on a hot water tap when someone is having a shower, and the dramatic drop in water pressure , normal followed by a shout “ turn that hot tap off “ I’m having a shower , this is due to the fact that a true combination boiler has no hot water storage tank like our combi boilers, which overcomes this problem, and allows multiple hot water taps or outlets to be used simultaneously, at good pressures.

Full technical output details for our combination boilers with storage for larger properties

These combination boilers for larger properties – can be fired with either natural gas or LPG / Propane Gas

Control options for the boilers

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 combi boiler can do this – they have a control panel is also what is called “OpenTherm Plus “compatible, which means you can control these combi boilers, via the use of an “OpenTherm” controller, such as a “nest” type or similar.

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.

The control panel on these combi boilers also has numerous inbuilt features such as –

• Frost Protection – Full protection against freezing of the heating and domestic hot water in low ambient temperatures
• Pump Protection system – Anti-blockage System -The circulation pump is activated automatically once every 24 hours and prevent any blockage
• Ability to operate according to different heat demands with the variable flow pump control
• Low fuel consumption and fixed combustion efficiency thanks to the PWM driver, high modulating fan and high modulating gas valve
• Ability to operate according to different heating system configurations

Last point is that all combi boilers when fuelled by gas 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.

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 function at the top of this web page, 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.

Electric Combi Boiler UK

Electric combi boiler UK? – are they available? do they work? Usually when someone says “electric boiler” the majority of people think about the water boilers used to generate instant hot water to a single tap, such as an over or under sink water heater, but these units only produce domestic hot water. Happily, in the UK, electric combi boilers are now a great solution, for not only your hot water requirements, but also your heating requirements.

Electric combi boilers by Flexiheat UK

As the boiler name suggests, they are an option to a gas or oil combi boiler that uses electricity as the energy supply. Despite the fact that technology is nearly as old as the invention of electricity itself, as of late electric combi boilers have seen expanded enthusiasm from people whose properties are not served by the national gas distribution system or who basically want to dispose of their gas supply and move to a greener energy to fuel their central heating and hot water requirements .

Electric combi boiler vs Gas

Knowing that natural gas is a fossil fuel, and therefore can’t be considered a green fuel source. With regards to electricity, if it is generated via renewable energy sources or if you use a wind turbine or solar panels to generate the electricity, you can go totally carbon neutral on your energy requirements. Utilizing electric combi boilers bodes well to individuals who have installed solar panels or wind turbines onto their property. Recent advances in the technology of solar and wind generation fields now make electric combi boilers a real solution for people who want to get off the national gas grid, or don’t want to use oil either.

Beside the fact that electric combi boilers in the UK, have the capacity to be eco-friendly, the other advantage is that an electric combination boiler is often smaller in size than an equivalent boiler fired by gas or oil, and will often fit in locations that a gas or oil boiler won’t , due to the fact that these boilers require a flue pipe or chimney system to operate.

Individuals who have previously experienced on demand electric water heaters, are usually disappointed with the DHW (domestic hot water) flow rate that they have seen.

This is solved with our 1 phase / 240 volt electric combi boilers as they can utilize an 80 litre indirect heated stainless steel hot water cylinder. This hot water cylinder allow these boilers a great hot water performance which are similar to their gas boiler equivalents.

When the units are over 15kW of output, you need a 3-phase electric supply – then you can produce enough hot water, both in temperature and quantity to not have a hot water storage element – but most properties in the UK, only have a single phase 240 Volt supply.

Cost of electric combi boilers in the UK

When it comes to the price of electric combi boilers in the UK, they are very similar to their equivalent gas fuelled equivalents, and are generally cheaper than their oil-fired equivalents, with prices generally in the £1,600 to £2,200 depending on the kW output of the boiler in question.  Obviously, they are more expensive than a heat only electric boiler, but when you add the necessary indirect cylinder required to do the domestic hot water requirements, and the controls required to achieve this, then they generally work out cheaper, than going for a split heating and how water system, that uses a heat only boiler and cylinder combination.

Electric combination boiler installation costs

The installation cost of an electric combi boiler in the UK, is often lower than their gas or oil alternative. No flue or chimney system has to be installed with an electric boiler, which cuts down on the labour required and should result in cheaper installation price. They include an inbuilt heating pump and expansion vessel, for both the heating and domestic hot water requirements, as well as safety valves, that ensure they security of your boiler. All that is required is the appropriate electric supply, with the required amps available, and a water supply and your ready to go as they say.

Electric combination boilers are a great choice in elevated buildings such as high-rise structures, as they don’t require a flue pipe system, as no products of combustion are given off with an electric boiler. Can you just imagine not only the logistical and high expenses associated with installing a gas boiler, in a high-rise block of flats, with scaffolding, and working at height legislation to comply with in the UK, just to name a few problems to overcome. These issues are just eliminated when choosing a combination electric boiler, making them a great solution to a complex problem.

Electric combination boiler reviews UK

When reviewing our range of electric combi boilers that we sell in the UK and Ireland, following are a few brief overview of the range we sell –

Our range of electric combi boiler can be powered by a single phase 240 Volt electrical supply from 4.5 kW to 15 kW, which is the largest power output we know of on the UK and Irish market.

We can go all the way up to 21 kW of boiler output, but from 15 kW to 21 kW you require a three phase 400 Volt electrical supply

We do a wall hung or mounted version, that has a 50 litre hot water internal storage vessel housed withing the boiler, thus ensuring good flow rates, and hot water that is hot enough for doing dishes – you require hot water at 50 degrees C to get rid of grease from cooking utensils and dishes. If you only have a shower in your house or flat, then this is the electric combi boiler for you.

We also do a floor mounted version, which has a larger 80 litre internal hot water vessel, again situated withing the boiler casing, this has enough capacity of hot water to run a bath at mains pressure, just as quick as a hot water cylinder would. If you have a bath in the property, again this is the combination electric boiler for you.

All of the boilers, have 6k W of dedicated electric heating power for the hot water production of the boiler.

These electric boilers can be set to a various output, for example the 45/90 model, can be set with an output of either 4.5 kW, 6 kW, 7.5 kW, or 9 kW to suit your heating requirements. These boilers are available in either wall mounted or floor standing versions.

The 10/15 boiler model, can be set to 10 kW, 12.5 kW or 15 kW output, giving you maximum flexibility to suit your needs

Whichever combination electric boiler you go for, all of them are highly efficient, at almost 100% efficiency (actually 99.8% to be precise)

For more full information, please see the following in depth dedicated web page https://www.flexiheatuk.com/product/electric-combi-boilers/

Should you require any more information or advice, on what we regard as the best range of electric combi boilers UK and Ireland wide, then please don’t hesitate to call us on 01202 822221 or send us an email via our contact form in the top tool bar