10 questions to ask before you accept a boiler quote

Two quotes for the same boiler can be £800 apart, and the cheaper one is not automatically worse. These are the questions that tell you which is which.

1. Is this price fixed, or an estimate?

A fixed price means the risk of surprises sits with them. An estimate means it sits with you. Get it in writing.

2. What's your Gas Safe number?

Then check it yourself on gassaferegister.co.uk. Any decent engineer expects this and will not be offended. One who bristles has told you something.

3. Does it include a system flush, and which kind?

A chemical flush and a power flush are not the same thing, and the difference is a few hundred pounds. On an older system with sludge, a chemical flush is not enough, and skipping a proper one can void your warranty.

4. Is a magnetic filter included?

Most manufacturer warranties now require one. If it is not in the quote, the quote is not comparable with one that has it.

5. How long is the warranty, and who registers it?

Warranties run from 2 to 12 years depending on brand and installer accreditation. It should be registered in your name - ask them to confirm they will do it, and check afterwards that they did.

6. Who notifies Building Control?

A gas boiler installation is notifiable work. Your installer notifies Gas Safe, who notify Building Control, and you get a certificate. If you sell the house without it, your solicitor will ask.

7. Are new radiator valves included?

Often not. It is a cheap thing to add at the time and an annoying thing to do later.

8. What happens if you find something behind the boiler?

Corroded pipework, an asbestos flue in an old property, a gas supply that is undersized. Ask what the process is if they find something on the day. A professional has an answer ready.

9. Who is actually doing the work?

The person who quotes is not always the person who fits. If it is subcontracted, ask for the fitter's Gas Safe number too.

10. What is not in this price?

The single most useful question you can ask, and the one that flushes out the difference between two quotes faster than anything else.