Guide to combi boilers

Are you worried that your ancient boiler is a ticking timebomb? Need a new boiler and want to cut your energy bills but have no idea which type to go for? Read our guide to find out if a combi boiler is right for you.

A combi boiler can save money,
energy and the environment

According to the Energy Saving Trust (EST), about 60% of the carbon emissions from a gas heated home are emitted by your boiler. Replacing your old G-rated boiler with a new A-rated condensing model can cut these emissions substantially and could save you up to a third on your fuel bills.

Alex Hunt, from Bright Green Homes in Brighton says: “One way of making your home more energy efficient is to replace an old boiler. If your boiler is over 15 years old then it won’t be eco-friendly, so replacing it will make a real difference to the energy efficiency in your home.”

What is a combi boiler?

According to Northern Gas Heating, combination boilers are found in 70% of homes in the UK, making them the most popular choice. They combine everything within a single compact unit, capable of providing heating and instant hot water without the need for a water cylinder. UK building regulations state that all new boilers must be condensed models to save energy and help the environment and most display SEDBUK A or B ratings to prove their efficiency.

How does a combination boiler work?

Cold water passes through the boiler over a heat exchanger. The exchanger transfers as much heat as possible from the burner and ensures that only a small amount is lost through waste gasses. This means that the boiler can provide hot water without the need for a cylinder with an immersion heater. Combi boilers also provide central heating by circulating hot water through radiators and underfloor heating.

What are the advantages and disadvantages of a combi boiler?

Take advantage of the government
boiler scheme, launched in January

“Combi boilers give you instant hot water and are energy efficient,” says Harvey Morgan, of HSM Plumbing, Central Heating and Boiler Repair Experts in Surrey. Condensing combi models convert 86% or more fuel into heat, compared with 65% in old boilers, reports the EST. This makes them extremely energy efficient.

As well as reducing your carbon footprint, a combi boiler can save you money on your heating bills: “It’s important to make sure you replace your boiler if it’s over 15 year old, this can cut your gas bills by an average of £300 per year,” Harvey explains. Another advantage of installing a combi boiler is that it is compact and fits neatly in cupboards or under the stairs to save space.

However, combi boilers struggle to supply hot water to more than one outlet so are more suited to smaller properties, usually with one bathroom. Harvey points out: “A combi boiler would suit someone with a flat or maisonette or a house with good water pressure.”

Installing a combi boiler

“In the right hands gas is perfectly safe, but in the hands of an illegal gas fitter it can kill,” says Phill Brewster, the Gas Safe Registers National Investigations Manager. It is important to make sure that you hire a Gas Safe engineer to install, replace, repair or service your gas combi boiler. Using an unqualified contractor or even trying to do the work yourself can be a fatal mistake. Always remember to have your gas boiler serviced annually to check it is in good working order.

How much does a combination boiler cost?

The cost of buying and installing a combi boiler will vary depending on what kind of heating system you are replacing. Harvey says: “If you already have a system boiler for instance, replacing with a combi would cost about £3,000.” You should get a quote from a boiler specialist to find out exact prices.

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