Why are boiler quotes so different?

If you have three quotes on the kitchen table and they are hundreds of pounds apart, the natural suspicion is that somebody is trying it on. Usually nobody is. The prices differ because the jobs they describe differ, and the odd thing is that the boiler itself, the line everyone stares at, is the one part of the quote you can be fairly confident is the same.

We put boiler enquiries in front of local installers around Northampton and Milton Keynes every week, which means we see different firms price the same house. The gaps between them are rarely mysterious once you know where to look. This is where they come from.

The boiler is the easy bit

A boiler is a manufactured product with a model number. Two installers buy the same model through the same merchants at broadly similar trade prices, so if two quotes name the same boiler, the difference between them is almost never the boiler. It is everything around it.

If the quotes name different boilers, compare what is actually being offered before comparing numbers at all. A premium brand fitted by an accredited installer can carry a guarantee of ten years or more, while a budget model may carry five. That is a real difference in what you are buying, not padding on the dearer quote, and it is the first thing to equalise before the prices mean anything.

Where the money actually moves

The lines that swing a quote are mostly the ones that describe your house rather than the appliance. In rough order of how often they explain a gap:

• The flue route. A boiler venting straight through the wall behind it is the cheap version. A vertical flue through the roof, extensions to clear a window or a boundary, or scaffolding to reach any of it, are real costs that one installer may have seen and another may not have looked for.
• The gas run. A modern boiler can need a larger gas supply pipe than the one feeding your current one, and rerouting or upsizing that run is a genuine piece of work. The quote that ignores it is not cheaper, it is incomplete.
• The condensate route. Every modern boiler needs a drain for its condensate. If there is no sensible route to one, creating it is on somebody's quote and missing from somebody else's.
• System cleaning. A chemical flush and a power flush are different jobs at different money, and which one your system needs depends on its age and condition. Two quotes with two different cleaning methods are not the same job.
• Making good. Boxing in pipework, patching plaster, filling the hole the old flue left. Some installers include it, some leave it to you, and few say so loudly.
• What is excluded. The quote that is a single line and a number has not listed its exclusions, which does not mean it has none.

Assumed, or surveyed?

This is the single biggest reason one quote sits well below the others: it assumes more and checks less.

A price produced over the phone or from a few photos has to assume the flue route is simple, the gas run is adequate, the system is reasonably clean and nothing awkward is hiding behind the boiler. An installer who has stood in your house, measured the gas run and looked at where the condensate can go has priced the job that actually exists. Those two numbers should not match, and the lower one is not the bargain it appears, because an assumption that turns out wrong does not disappear. It comes back on installation day as a variation, at a price you are in no position to negotiate with the old boiler already off the wall.

There is a simple test. Ask each installer what happens to their price if the gas pipe needs upsizing or the flue needs extending. The one who has surveyed properly can answer, because they have already checked. The one who quoted from assumptions will tell you it depends, which is true, and is exactly the problem.

Two differences that are about the firm, not the job

VAT registration is the quiet one. A smaller firm below the VAT threshold is a fifth cheaper on paper for identical work. That is neither a saving nor a con, but it does mean two honest quotes can sit 20% apart before either has touched your house.

The other is what happens after the fitting. Every gas boiler must be installed by a Gas Safe registered engineer, and the installation must be notified so you receive a Building Regulations Compliance Certificate. Registration of the manufacturer's guarantee has a deadline measured in weeks. A quote from a firm that handles the notification, the registration and the commissioning paperwork as standard is buying you things the bare number does not show.

Source: Gas Safe Register

How to line three quotes up

You cannot compare quotes as numbers. You can compare them as documents. Ask each installer for a written, itemised quote that names the boiler model and guarantee length, describes the flue work, states the cleaning method, lists the controls being fitted and says what is excluded. Then put them side by side and make the jobs match before you look at the totals.

Where one quote includes something the others do not, ask the others why not. The answers are usually more informative than the prices: either the item is unnecessary and the dearer quote is padded, or it is necessary and the cheaper quotes will bill it later.

Three properly surveyed quotes is the practical number, enough to see the pattern without drowning in appointments. If you would like three from vetted local installers who quote from a survey rather than a guess, tell us about the job and we will arrange it, with no obligation.