Boiler repair in London
Pressure loss in flats, sludge and stuck valves in terraces. Know typical London repair costs before a Gas Safe registered engineer arrives.
Boiler faults common in London homes
In London flats, the usual trouble is a combi losing pressure or a condensate pipe that has blocked. In older terraces, it is more often sludge in the radiators, a tired pump or a valve that has stuck. When a boiler is past 12 years old, ask for a replacement quote too so you can see both numbers side by side.
Victorian and Edwardian terraces: Long pipe runs to upper floors and old radiators full of sludge are typical. A power flush or magnetic filter often fixes poor heating on the top floor.
Converted flats and mansion blocks: Pressure drops, blocked condensate pipes and failing diverter valves are the faults engineers see most in flat combis.
Outer-borough 1930s semis: Ageing motorised valves, worn pumps and leaking cylinders are common on the older open-vented systems.
Boiler repair prices in London
| Job | Typical price | Typical visit |
|---|---|---|
| Diagnostic visit | £80 to £120 | about 1 hour |
| Pump, valve or fan replacement | £150 to £350 | 1 to 3 hours |
| Main circuit board (PCB) | £250 to £450 | 2 to 3 hours |
| Annual boiler service | £80 to £120 | about 1 hour |
Typical prices including VAT, checked October 2026. Your installer gives you a fixed price in writing before any work starts. More detail in our boiler repair cost guide.
Boiler over 12 years old?
Repeat repairs on an old boiler add up. Compare a fixed replacement price in London before you pay for another part.
See boiler replacement optionsAreas we cover around London
- Islington
- Hackney
- Camden
- Brixton
- Wimbledon
- Ealing
- Croydon
- Walthamstow
- Greenwich
- Richmond
Also nearby: Boiler repair in Reading, Boiler repair in Luton, Boiler repair in Chelmsford, Boiler repair in Brighton
Boiler repair in London: questions
What does a boiler repair cost in London?
The first diagnostic visit in London is normally £80 to £120. Most part replacements, such as a pump, fan or valve, cost £150 to £350 fitted, and a new circuit board £250 to £450. Nothing is replaced until you have agreed the cost.
Why is the top floor of my terrace cold when the rest is warm?
Usually it is sludge or air in the system, or a pump that is losing strength. Bleeding the radiators is a good first step. If that does not help, an engineer can flush the system or check the pump.
My flat's boiler keeps losing pressure. What should I do?
Top it up to about 1 to 1.5 bar using the filling loop, as the manual explains. If it drops again within days, there is likely a leak or a worn pressure relief valve, and an engineer should take a look.
What if I can smell gas?
Get everyone out, avoid switching anything on or off, and ring the National Gas Emergency Service on 0800 111 999. Once they have made the supply safe, you can book a repair.