Calculating costs of a boiler.

Our boiler buying guide takes you through the important factors you need to consider when looking to buy a new boiler. One of them is the size of your household and how you intend to use the boiler. The next thing is the size and make of the boiler as there are different boiler types in the market. Lastly, the cost of a new boiler is another factor to consider.

Boiler Efficiency

Boiler efficiency is important as they are contributors to CO2 emissions; up to 60% in homes. If you want to cut on your energy bills and carbon output, then you should make a wise choice when choosing and buy the best boiler. It is vital to replace an old boiler with a non-condensing system with a modern one that will improve efficiency by a third in addition to saving you money on energy bills. The key to getting the best boiler is to buy one which is in the right size and type for your space.

Getting the right size for your boiler

When it comes to size, you should consider the boiler’s heating and hot water ability. The physical size is also important as it has to fit into its designated space. The heating size will depend on the number of bathrooms in your house and the number of people living there. You can consult a heating engineer to guide you based on the factors above.

Gas boiler

If you are connected to a gas heating system that has a gas boiler, you can choose between a Combi boiler and a Heat-only boiler. A Combi boiler supplies heat to your domestic water needs and your radiators while a Heat-only boiler which has a cylinder for hot water storage that is fed by a cold water tank. There is also a system boiler that is similar to a heat-only boiler but without the provision of a cold water tank.

How to Save Money by Purchasing an Efficient Boiler

If you already have a boiler, you need to check its efficiency rating. A new boiler is A-rated which basically means that its efficiency is over 90% whereas an old boiler could even reach the G-rating level making its efficiency to be below 60%. If you live in a 4 bedroom detached house and have a G-rated boiler, you could actually save around £305 annually which translates to £25 per month which is more than new boiler finance. The average cost of a new boiler depends on the size and brand but the average cost of a new boiler is between £500 and £2,500.

How Much to Install a Boiler

How much to install a boiler depends on the number of rooms in your house and number of people living there; the following is a table indicating the cost of installation for boilers with different ratings.

Brand Boiler types Fuel types Warranty range Price range Trustpilot Score
Grant Combi Regular System Oil 2 to 5 years £1,250 – £3,100 9.4/10
Ideal Combi Regular System Gas 2 to 5 years £700 – £4,500 8.5/10
Vaillant Combi Regular System Gas 2 to 5 years £750 – £2,500 8.9/10
Viessmann Combi Regular System Gas Oil 2 to 5 years £840 – £2,900 9/10
Worcester Bosch Combi Regular System Gas Oil 2 to 6 years £800 – £2,350 9.1/10


There are a range of new boiler finance options available to make sure you’re getting the best deal for a new boiler.

Key Features of a Boiler

Condensing vs. Non-Condensing

A condensing boiler uses water vapour that is produced during the heating process and utilizes waste heat to heat cold water in advance that is getting into the boiler. These types of boilers are energy efficient as they are able to provide sufficient heat even under low temperatures.

Non-condensing boilers function at high temperatures where heat is lost outside the premises. They have an efficiency of between 80-88% whereas condensing boilers have an efficiency of more than 88%.

Sealed vs. Non-Sealed Combustion

A boiler either has a sealed or non-sealed combustion unit. However, one with a sealed combustion unit is better as it fetches air from the outside into the burner and removes exhaust gases out of the house. In addition, sealed combustion boilers do not bring dangerous gases inside the house.

Non-sealed boilers bring heated air in and direct it up in the chimney thus results in wastage of energy used in heating the air.

Other Factors to Consider Before Buying a Boiler


If your home is in a place with warm climate, you do not require a central heating system but if you are in a cold place, a central heating system is a requirement hence a boiler is ideal for you. When in a warm place, you should consider buying a heat pump which will cater for all your air conditioning requirements and modest heating needs such as heating bath water.

Type of Fuel

Boilers that use gas are cheaper to operate than those that use oil. However, the type of fuel you choose will depend on what is available in your locality as there are places where there is a gas heating system.


Boiler are only for provision of heat, therefore, a cooling system is also necessary to have if you need to air condition your house.

How to Boost the Efficiency of your Boiler

Increasing the efficiency of your central heating system will enable you buy a smaller and cheaper system.

To increase your boiler’s efficiency:

  • Insulate your walls and attic
  • Put weather stripping on your doors and caulk on windows to prevent escaping of heat
  • Insulate ducts on the cooling system in attics and crawl spaces
  • Regularly clean the chimney
  • Set a clockwise movement of your fans to keep heated air down
  • Put in place automatic thermostats to reduce temperatures during the night and when there is no one in the house.

Make it a point to bring in a heating professional to service your boiler at least once a year. Your boiler could be malfunctioning without your knowledge leading to high maintenance costs and also could be a danger to your family.

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