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Choose the Right Boiler for Your Home - Combi, System or Regular?

Boilers account for around 55% of domestic energy consumption, so have a huge effect on your household energy costs. Choosing the right type of boiler for your lifestyle and your heating system can make a big difference to your comfort and your energy efficiency.

For example, the Energy Saving Trust calculates that if you have an old gas boiler with no controls, replacing it with an A-rated high-efficiency condensing boiler and full set of heating controls will significantly cut your home's carbon dioxide emissions, while potentially saving you up to £305 a year.

Modern boilers are more efficient for several reasons, but their main advantage is that since 2005, all new and replacement installations in the UK have to be condensing boilers. Since 2010, this regulation has been tightened to only A-rated energy efficient boilers (at least 88% efficient).

Any well-maintained boiler will burn its fuel very efficiently, but inevitably some heat is lost in the hot gases that escape through the flue. A condensing boiler has a bigger heat exchanger, so it recovers more heat, sends cooler gases up the flue, therefore is more efficient than a non-condensing type.

Sometimes the flue gases get so cool that the water vapour in the gas condenses out (hence the name). When this happens, even more energy is recovered from the condensing vapour, and the efficiency gets higher still.

There are three main classes of condensing boiler to choose from. Making the right decision for your family depends on how you use your hot water and heating system.

As a rough guide, here is a brief outline of the three types:
Combi BoilersSystem BoilersConventional Boilers
Combination boilers, or combi boilers for short are probably the most popular choice currently. They produce hot water on demand so in theory are the most efficient as you only pay for gas to heat the water that you use at the time. The only downside is that if you need hot water from more than one tap at a time, you may experience a reduction in hot water pressure.System boilers, or sealed system boilers have a water cylinder, usually in an airing cupboard or similar, offer more flexibility for families who use hot water in more than one place at a time. They don't need a tank in the loft for pressure and can provide for multiple hot taps at any given time. The hot water can run out though and then there is a slight delay while re-heating the cylinder.Regular or conventional boilers, otherwise known as open vent boilers heat water in a cylinder and a tank, usually in the loft. They are somewhat more efficient than combi boilers at heating the water in the first place, but even with good insulation, this heat can be lost by radiation from the tank, so these systems are best suited to installations where hot water is used up fairly quickly. Multiple hot taps can be served at any given time, but the hot water may run out and need to be re-heated.


Heat recovery systems can save up to 17% of the energy used in heating your water. Some of the heat generated by your boiler escapes through the flue. Passive flue gas heat recovery systems capture some of this lost energy and use it to heat your water, making your heating system more efficient and saving money.

The energy efficiency rating system for boilers is called SEDBUK (Seasonal Efficiency of Domestic Boilers in the UK). All boilers are assessed and given a rating to help you pick a boiler that is energy-efficient, or see how efficient your existing boiler is. At Divine Water, we specialise in advising on the best boiler for your needs and installing your new boiler to the highest standards of safety and efficiency. Call us today or click in the header of any page to email us for sound, unbiased advice.

Independent, Impartial Advice & Service

As Divine Water is not tied to one manufacturer of boilers, the advice that you get will be based purely on the heating needs of your home and family. We can install and service boilers from all the major manuracturers including:

 
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