Questions to ask a boiler installer

The short answer

Before you choose anyone, ask these six questions. A good installer will be glad you did, and the answers make quotes much easier to compare.

1. 1Can I see your Gas Safe ID card? Check the card is current and that the back lists gas boilers.
2. 2How have you sized the boiler? Listen for bathrooms, hot water use and mains flow, not just the number of bedrooms.
3. 3Is the price fixed, and what isn’t included? You want a written price that lists the work.
4. 4Will you clean the system first? It protects the new boiler and is required by manufacturers.
5. 5Who registers the warranty and notifies Building Control? Both should be done for you, in your name.
6. 6What happens if something goes wrong after you leave? Know who to call and how the warranty works.

How to check the Gas Safe Register

By law, anyone working on gas appliances in your home must be on the Gas Safe Register. It takes a minute to check, and it is worth doing for anyone, whoever recommended them.

1. 1Ask the business for its Gas Safe registration number. Ours is 567789, for On Track Plumbing & Heating Ltd.
2. 2Search for it on the Gas Safe Register’s “Find an engineer” page and check the business name matches.
3. 3On the day, ask the engineer for their Gas Safe ID card. It has their photo, licence number and an expiry date.
4. 4Turn the card over. The back lists the types of gas work the engineer is qualified to do. Make sure it includes the work you are having done, such as gas boilers.

Questions about the boiler itself

A good installer recommends a boiler for your home rather than the one they happen to stock. Ask why they chose the type and the size. For a combi, they should have looked at your mains flow and how many showers run at once. For a system boiler, they should have considered your hot water use and the space for a cylinder. If you have a cylinder and they suggest switching to a combi, ask what you will gain and what you will lose.

• Will the gas pipe from the meter need upgrading for this boiler?
• Where will the flue come out, and is the position within the rules?
• Where will the condensate pipe drain, and how is it protected from frost?
• Which controls are included, and how do they meet Boiler Plus?

Questions about the quote

Two quotes for the same boiler can differ a lot because they include different work. Ask each installer to list what is included so you can compare like with like. Our page on boiler installation cost explains what moves the price.

• Is the system clean to BS 7593 included, and will it be a chemical clean or a power flush?
• Is a magnetic system filter included, and where will it go?
• Is the flue kit new?
• Is removing and disposing of the old boiler, tanks or cylinder included?
• When is payment due, and is anything charged before the work starts?
• How many days will the job take, and will I have heating overnight?

A price that grows on the day is what most people want to avoid. A fixed written quote that lists the work protects you from that.

Questions about paperwork and aftercare

The paperwork matters when you claim on a warranty or sell the house, so ask who handles it. The manufacturer’s warranty usually has to be registered shortly after installation. The installation must be notified to Building Control, which Gas Safe registered installers do through the Gas Safe Register. And the Benchmark commissioning checklist should be filled in and signed on the day.

• Will you register the warranty in my name, and how long is it for this model?
• Will I receive the Building Regulations Compliance Certificate?
• Do you offer a guarantee on your own workmanship, separate from the manufacturer’s warranty?
• Who should I call if the boiler shows a fault in the first few weeks?
• Can you service the boiler each year to keep the warranty valid?

Extra questions for flats and rented homes

If you live in a flat, the building may come with rules of its own. A new flue position, or a flue through a shared wall, can need permission from the freeholder or managing agent, and some leases say who may work on the building’s gas supply. Ask the installer whether the flue will stay in the same place, and check your lease before you book. See boiler replacement in flats for more.

If you rent, the boiler belongs to your landlord, so they or their agent need to agree the work and the price. If you are a landlord, ask the installer how they will arrange access with your tenant and whether they can carry out the annual gas safety check at the same time as a later service.

What a good installer does without being asked

Some things are worth noticing. A good installer asks you questions before quoting: how many people live there, how many bathrooms, what is wrong with the current setup. They tell you when a repair is the more sensible choice, or when the boiler you have asked for won’t suit your home. And their quote reads as a list of work, not just a boiler name and a total.

If you would like to see how we answer these questions, ask us. Send your details through the quote form and an engineer will come back with a fixed written price and a recommendation, or read about our boiler replacement service first.