Same boiler type
All combi, all system, or all regular, not a mix.
How to compare boiler quotes without getting caught out
Getting multiple quotes is sensible. But comparing them fairly means knowing what to look for and what installers sometimes leave out.
Quote comparison checklist
- Boiler make and model (not just 'equivalent' or 'similar')
- Boiler output in kW, appropriate for your home
- Flue type and length if non-standard
- What controls are included (thermostat, programmer, TRVs)
- Whether a system flush is included, and what type
- Gas pipe upgrade if needed
- Any pipework modifications, clearly described
- Warranty length and exactly what it covers
- Whether building control notification is included
- Payment terms and deposit requirements
- An estimated completion date
- What happens if extra work is needed
Comparing apples with apples
Similar output rating
Within 2–3kW of each other for a fair comparison.
Same warranty length
Compare the total warranty, not just the boiler's standard cover.
Matching extras
Controls, flush, filter, TRVs, include the same items.
If one quote is significantly cheaper, check what's missing. If one is much more expensive, ask what extra value it includes.
Red flags to watch for
- Vague descriptions ('boiler as discussed', 'plus sundries')
- No specific make and model mentioned
- Pressure to sign today or lose a 'special price'
- A very low deposit with the balance due before work starts
- No mention of Gas Safe registration
- A quote only valid for 24–48 hours
- A large discount for an immediate decision
- A warranty that depends on an ongoing service contract
- No written breakdown of what's included
Important: legitimate installers expect you to get multiple quotes and won't pressure you into a same-day decision.
If you feel rushed, that's a warning sign.
What you can safely ignore
- Brand loyalty claims, 'we only fit X because they're the best' is marketing, not fact.
- Efficiency percentages, all modern boilers are 90%+ efficient; differences are marginal.
- Energy-saving promises, actual savings depend on your usage, not the boiler alone.
- Awards and 'installer of the year', often paid for or self nominated.
Questions to ask before accepting a quote
"What happens if you find a problem once you start?"
A good answer describes a clear process for approval before any extra work is done.
"Is the warranty with you or the manufacturer?"
Understand who you'll call if there's a problem, and for how long.
"Can I see your Gas Safe ID?"
Non-negotiable. Verify it on the Gas Safe Register website.
"Do you notify building control or use a competent person scheme?"
This should be included in any reputable installation.
"What's your typical lead time?"
Very busy installers are often busy for good reasons.
What to do next
Once you know how to compare quotes, make sure you can verify an installer's credentials and know what good aftercare looks like.