Survey finding
Back boiler on your survey: what to do
Back boilers are end-of-life technology. This page covers the realistic replacement costs.
Last updated: 6 May 2026. Editorially reviewed: 20 May 2026.
Finding
Back boiler
What this usually means
Back boilers sit behind a gas fire in the chimney breast. They are old technology, low efficiency (60-70% vs 90%+ modern), and increasingly hard to service as parts become scarce. Some are in good order; many are condemned at first inspection.
Why it matters
Replacement involves removing the gas fire, capping the flue, and installing a modern boiler elsewhere. Cost is materially higher than a like-for-like boiler swap.
Ask your surveyor
- Check:Is the back boiler operational?
- Check:Is the gas fire compliant?
Ask the seller
- Check:When was the back boiler last serviced?
- Check:Is the original installation paperwork available?
Next steps
- •Get two written quotes from local trades before negotiating with the seller.
- •Speak to your mortgage broker before exchanging if the finding affects mortgageability.
Tool shortcut
Check the property before you offer
Flood, subsidence, EPC, crime, schools, transport, broadband, tenure, age, listed status and price checks where data is available.
Run a free previewCross-check this finding with EPC, building age, and address-specific risk data.
What you need to know
Severity
Significant. Specialist follow-up usually warranted before exchange.
Typical cost to fix
Removal of back boiler and gas fire, plus new combi boiler in a different location: £3,500-£6,500. Plus chimney capping and decorative making good £400-£1,000.
Mortgage impact
Standard if boiler is operational.
Insurance impact
Standard.
When to pull out
Not on its own.
When to renegotiate, and by how much
Cost of full replacement system; typical reduction £3,000-£6,000.
Thinking of pulling out or renegotiating? What to do after a bad survey
Run the check on this address
The Survey Decoder explains the wording. The full report adds address-specific flood, subsidence, EPC, crime, listed status, building age and price comparison data, so a single finding isn't judged in isolation.
Run the check
Check the property before you offer
Flood, subsidence, EPC, crime, schools, transport, broadband, tenure, age, listed status and price checks where data is available.
Run a free previewHow MyPropertyScan produces this guide, and what it is not
Published by MyPropertyScan and written by Ziad Nasr, who is accountable for its accuracy. No page here is written or reviewed by a chartered surveyor, conveyancer or regulated adviser, and we do not claim otherwise.
This page is not:
- Chartered surveying — we do not inspect properties or produce RICS Home Survey reports
- Legal advice — we do not act as conveyancers or advise on title, tenure or contracts
- Mortgage or insurance advice — we are not regulated by the FCA and give no recommendations
Figures and process steps come from the published UK datasets and standards listed on this page, not from professional practice. Pages are updated when source coverage, survey cost assumptions, or lender and legal requirements materially change. Dataset limitations are set out on the methodology page.
Spotted something out of date or wrong? Email hello@mypropertyscan.com and we will correct it and change the update date.
Sources used
We use UK public and specialist sources where they are available. Public datasets can be incomplete, delayed, or missing for some addresses. Treat them as a starting point, not as a replacement for professional advice.
Source standard: preference goes to official government datasets, statutory bodies, professional standards, and primary dataset publishers. We cite the source family on the page and explain coverage limits rather than filling gaps with unsupported estimates.
- Professional standard: RICS Home Survey StandardRICS standard for condition-based residential surveys in the UK.
- Learn more from: RICS consumer guide to surveysConsumer-facing guide to survey types and when each level is appropriate.
- Official guidance: GOV.UK buying or selling your homeGovernment overview of the home buying and selling process.