Cost of Boilers

When your boiler packs in, it might be tempting to take the first quote you receive – but if you can hang out for a couple of days, a little bit of investigation and receiving a few quotes could save you a lot of money.

There are a number of factors to take into account before purchasing a boiler: Csuch as the size of your home, the type of fuel you use, how much hot water you use and how old your current boiler is.

The cost will vary depending on the size of the boiler you’re installing, whether you’re switching the type of boiler you have or need new radiators.

The information below will help give you an idea of how much it will cost to replace your boiler.

How much do boilers cost?

Overall, the cost of replacing your boiler will be approximately £1,000 – £3,000, including installation costs:

  • The actual boiler will cost you anywhere between £600 and £3,000.
  • The installation costs will be between £500 – £1,500 depending on the installer you use and your requirements.
  • The cost of installing a new boiler will depend on the size, type and brand of boiler you require and the installer you use.

It will also depend on whether you’re switching fuel type, changing position of the boiler or adding radiators.

How much does a typical combi boiler cost?

The most common type of installation is replacing a combi with a combi, in the same place. Here are some basic prices according to the Energy Saving Trust:

Company Boiler Type Boiler Size Boiler Model Typical cost incl. installation
Baxi Combi 24kW Duo-tec 24 HE A £1,410.00
Vaillant Combi 24kW ecoTEC plus 824 £1,779.60
Glow-worm Combi 28kW Betacom 28a £1,450.80
Worcester Bosch Combi 28kW Greenstar 28i Junior £1,671.60
Ideal Boilers Combi 32kW Vogue 32 £1,796.40
Vaillant Combi 32kW ecoTEC exclusive 832 £2,181.60
Ideal Boilers Combi 35kW Logic 35 £1,558.80
Baxi Combi 40kW Duo-tec 40 HE A £1,644.00

Source: Energy Savings Trust price guide

What is the cheapest fuel for my boiler?

There’s been lots of back and forth about whether oil, gas or electricity is best to heat a home. The consensus is that mains gas is the cheapest fuel to heat a home. Here is a very quick overview of the cost of different fuels:

Heating costs in the average home
Mains Gas 4p / kWh
LPG Gas 7.5p / kWh
Heating Oil 6p / kWh
Bottled Gas 14p – 32p / kWh
Electricity 15p / kWh


To buy one unit of mains gas (measured in kWh) you will pay about 4p / kWh. Gas is regarded as the cheapest fuel, roughly 3-4 times cheaper than electricity per kWh.


To buy one unit of heating oil (measured in kWh) you will pay about 6p / kWh. This is the cheapest alternative for those 1.5 million homes that are not connected to the main gas.


To buy one unit of electricity from the mains (also measure in kWh) will cost you about 15p / kWh. In comparison, to buy one unit of mains gas (measured in kWh) you will pay about 4p / kWh.

Although they are more expensive than gas boilers, electric radiators are 100% efficient and they will turn 1 kWh of electricity into 1 unit of heat. Boilers won’t. Even a brand new boiler will only be about 90% efficient.

Should I replace my old boiler?

Think of it like this – if your current boiler is 65% efficient, this means that for every £1 you spend on your heating, 35p is being wasted. By comparison, with modern boilers that are 90% you will only lose 10p for every £1 that you spend.

By replacing your old, inefficient boiler with a new A-rated boiler you could reduce your gas bills by roughly £340 a year.

If you are eligible, you could have your old gas boiler replaced for free via the ECO boiler grant scheme. Read more about the ECO boiler grant scheme.

Is now the right time to replace your boiler?

Here are five questions that should help to decide if now is the time to replace your boiler:

  1. Are you having persistent breakdowns?

    If the cost of continuously repairing your boiler is outweighing the cost of renewing it.

  2. Is you boiler G-rated?

    To check the efficiency rating of your boiler – click here.

  3. Is your boiler noisy?

    Sometimes boilers make an irritatingly loud ‘kettling’ noises. Kettling is usually caused by products of corrosion of the insides of the radiators etc. accumulating inside the boiler heat exchanger.

  4. Is your boiler on the floor?Most new boilers are wall-mounted. If yours is on the floor, then it’s probably older and less energy-efficient than the new boilers.

  5. Can you control your heating?Some old boilers don’t have controls to allow you to properly control your heating. It will help you cut your heating bills if you have a flexible timer or controls, as well as a thermostat.

  6. Other considerations include:

    Flue problems, environmental pollution, green house gases and fuel efficiency.

Do you think it’s time to change your boiler? Get 3 quotes from local installers in your area and get all the advice you need.

Will I get a return on my investment?

Installing a new boiler will save you up to £340 per year on your energy bills, according to The Energy Savings Trust.

This is because if your boiler is old it could have a G-rated efficiency rating – meaning for every £1 you spend on fuel you could be losing 40p on wastage.

Type of Property Typical cost of boiler and installation Energy bill savings Time to return on investment Return on investment after 10 years
Detached house £3,020 £570 5.2 years £2,680
Semi detached house £2,632 £340 7.7 years £768
Detached bungalow £2,320 £290 8.0 years £580
Mid terrace house £2,320 £280 8.3 years £480
Mid floor flat £2,112 £145 14.6 years -£967

Source: Energy Savings Trust

Although replacing your old boiler is not seen as a big long term investment like solar – it is well worth it when you are losing money on old inefficient boilers.

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