So how many different boiler types are there and how do they differ from each other?  Well remember that a boiler doesn't have to use natural gas to burn and produce heat, oil, propane gas and electricity are used and I suppose a ground source or air source heat pump can be classed as a boiler aswell.

Lets also clear up the condensing bit as well.  For years a boiler was a boiler, it burnt a fossil fuel and this produced heat but in April 2005 the building regulations were ammended so that any boiler installed or replaced needed to be SEDBUK A rate efficient.  This meant that all of the boiler manufactures had to make their boilers more efficient and the easiest way to do this was to make them a condensing boiler.  A condensing boiler still burns a fossil fuel but the boiler extracts more heat from the exhaust gasses which would normally be released outside via the flue.  This in turn means the water vapour within the exhaust gases cools and turns into condensed water.

Hopefully that makes sense and you now understand what a condensing boiler is, lets move onto the different types of boiler

Combination Boiler

A combination boiler or 'combi' is a very clever space-saving idea, and an increasingly popular choice in UK homes. In fact, combis now account for well over half of the boilers sold in the UK each year.

A combi boiler is both a high-efficiency water heater and a central heating boiler, combined (hence the name) within one compact unit. Therefore, no separate hot water cylinder is required, meaning the traditional airing cupboard can be converted into something else.

Further benefits of a combi boiler includes hot water being delivered through your taps or shower at mains pressure. So you can enjoy powerful showering* without the need for a pump.

Another combi boiler benefit is that it can generally save you money on installation time and costs, since no tank in the roof space means less pipe work and a shorter installation time.


System Boiler

A system boiler heats your central heating system directly and produces central heating water which heats your hot water cylinder.

A system boiler, just like a regular (conventional) boiler works on the principle of stored hot water. However, a system boiler differs from a regular boiler because the pump and sometimes other components of the heating system are incorporated into the boiler.  The central heating system with a system boiler is always pressurised, this means that the feed and expansion tank in the loft is not needed and the central heating system is filled up via the cold water main.


Regular Boiler

Regular boilers do the same thing as a system boiler but the central heating is not pressurised, therefore a feed and expansion tank is needed at the highest point of the system, normally the loft.

If you want hot water with your regular boiler then you'll need a hot water cylinder.

Traditional heating systems will use a regular boiler, system boilers are a more modern way of installing a heating system.


Electric Boilers

These are similar to the boilers above and can be central heating only or a combination boiler.  Instead of burning a fossil fuel the boiler uses electrical elements which are heated via electricity, similar to a kettle.  Central heating water is heated by passing over these elements.


Air Source Heat Pumps

An air source heat pump extracts heat from the outside air in the same way that a fridge extracts heat from its inside.  It is essentially the reverse of an air conditioning system, it can extract heat from the outside air even when the temperature is as low as -15° C.  Heat pumps have some impact on the environment as they need electricity to run but they are efficient and are predicited to become more and more popular as a heating source in years to come.

Due to the air source unit being installed outside the central heating system needs to have anti-freeze added to it and the anti-freeze level should be checked on an annual basis.


Ground Source Heat Pumps

Ground source heat pumps use pipes which are buried in and extract heat from the ground. This heat can then be used to heat radiators and hot water in your home.
A ground source heat pump circulates a mixture of water and antifreeze around a loop of pipe, called a ground loop or the pipe work is laid into a vertical bore hole – these are buried in your garden.  Heat from the ground is absorbed into the fluid in the pipe work and then passes through a heat exchanger in the heat pump.  Ground stays at a fairly constant temperature under the surface, so the heat pump can be used throughout the year.

The length of the ground loop or number of bore holes depends on the size of your home and the amount of heat you need.

This form of heating is gaining in popularity but initial installatin can be very expensive.



We hope that this clarifies the different types of boiler and you will be able to identify the system you have at home and the system you may wish to change to in the future.

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