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How to choose a boiler

publication date: Sep 12, 2017


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  Does your boiler need replacing? Check this and the potential savings you could make by visiting  the Energy Saving Trust website. 

First, make a note of your existing boiler’s details:

  • Make and model?
  • Age of boiler?
  • Energy rating?
  • Is there a flue?


Consider replacing your boiler about 6-8 weeks before required as good gas engineers are likely to be booked up, especially during autumn/winter.


Work out what size boiler you are likely to require; make a list as follows before you approach any companies or research boilers:

  • How many people live in your home?
  • How often and how many people come to stay regularly?
  • How many radiators are in your property?
  • Do you have a separate hot water tank?
  • How many showers do you have?
  • How many showers are thermostatic?

To help you choose the right boiler, make sure you understand the pros and cons of a combi boiler (heats both water and heating), and a conventional boiler (typically heats water separately with a hot and cold water tank).


Avoid cowboys; understand the jargon. For example, what does “Boiler Performance Technical Specifications” mean?


Know example costs of fitting a boiler prior to securing quotes; costs are from £1,000 through to £3,000+, according to a survey from Installer Magazine, most people underestimate the cost of fitting a boiler.

  When choosing a company to provide and/or install your boiler, make sure you check the following:

Ensure they are Gas Safe Registered – you can check here.

Find a reputable company via a site such as Checkatrade, or  quote from a utility company

Secure three quotes to upgrade or fit a new boiler.

Ask for a for a breakdown of labour and material costs.
Find out if you need to pay up front or if you can pay monthly, if that’s what you prefer.

Understand what boiler maintenance/servicing is required and likely costs. Is an annual service required by the installer, If so at what cost?

Check quotes to ensure you compare like with like, eg do all quotes include VAT, what are the actual boiler costs and what is the engineer’s hourly/daily rate?

Talk to your expert and find out if fitting thermostats on radiators at the same time as having a boiler fitted will reduce future heating costs further.

Find out what guarantees and for how long they are for. Check if they apply to both labour and parts.

How long will you be without heating and hot water while the boiler is being fitted?.

If you are at home during the work, or if it takes longer than expected, how long can you keep warm and heat water?

What paperwork will you receive after the boiler is fitted? Most require a building regulations certificate or you will struggle to sell your home.

What happens if there is a problem once the boiler is fitted? If you can’t resolve a dispute, what third party independent complaints procedure is there? For example, Gas Safe Register.


All our information is brought to you by Kate Faulkner OBE, author of Which? Property books and one of the UK's top property experts.
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