Boilers, radiators, underfloor heating, hot water cylinders. Free site visits, written quote.
Heating systems get neglected until they fail in January. By then the cylinder is leaking, the boiler is short-cycling, three radiators are cold at the top, the timer is set to the wrong year, and the immersion has been carrying the whole house for a week. TrustBuilt Projects covers the full heating and hot water side of a London home — gas combi and system boilers, vented and unvented hot water cylinders, traditional radiators, underfloor heating, smart controls and zoning. Gas work is delivered by qualified gas engineers on our team; plumbing, pipework, radiator runs, cylinder swaps and electric immersion work sit alongside that so the whole system gets looked at as one thing rather than three separate trades. Where heating work touches the wider house — lifting floorboards to run new pipework, boxing in pipework cleanly, making good plaster after radiator moves — we have the carpenters, plasterers and decorators in-house to finish it properly. We work across every London borough within 20 miles of the centre and quote in writing after a free site visit.
Typical jobs include combi boiler replacements, system upgrades from vented to unvented hot water, full system flushes, radiator additions and removals, underfloor heating installation in extensions and bathrooms, smart thermostat setup, and diagnostics for systems that aren't getting warm in the right places. All gas work is delivered by qualified gas engineers on our team. We cover every London borough within 20 miles of the centre and book a free site visit before anything is quoted in writing — particularly important on heating jobs where the right answer often depends on the existing pipework, the cylinder location and your usage patterns.
We visit your property, assess the work needed, and listen to your priorities.
Itemised quote in writing within 48 hours of the visit.
Our team carries out the work. Daily progress updates if you want them.
Final walkthrough, snagging, full clean. We leave your home spotless.
A like-for-like combi boiler swap in London typically falls between £2,200 and £3,400 including the unit, fitting and a system flush. Moving the location, upgrading from a system to a combi, or fitting a larger unit pushes it to £3,500–£5,500. Full unvented cylinder installations sit in a similar bracket. Written quote after the free site visit.
Yes. Gas work — boiler installations, gas pipework, commissioning — is delivered by qualified gas engineers on our team. They work alongside our plumbers, electricians and carpenters so you don't need to coordinate separate trades for the wider job.
Cold at the top usually means air trapped in the system and needs bleeding. Cold at the bottom usually means sludge build-up in the radiator and the system needs a chemical clean or power flush. Some cold radiators on a system are a balancing issue and just need the lockshield valves adjusted. We diagnose first rather than swap parts on guesswork.
Yes, with some caveats. Ground-floor extensions and new screeds are the easiest. Retrofit into an existing solid floor needs the floor lifting and rebuilding, so it usually only makes sense alongside other renovation work. Suspended timber floors can take low-profile UFH between joists. We'll talk through what makes sense for your floor build-up at the site visit.
A vented system has a cold tank in the loft and runs at low pressure — fine for older houses, weak for modern showers. An unvented cylinder runs at mains pressure, gives proper shower flow even on upper floors, but needs annual inspection and slightly more space. Most London upgrades go from vented to unvented for the shower performance.
Yes. We install and configure smart thermostats — Hive, Nest, tado, Honeywell — including multi-zone setups where different floors or rooms run on separate schedules. We can also bring older systems up to a point where smart controls work properly with them.
A straightforward combi swap in the same location is normally a single day — out, in, commissioned, tested. Relocating the boiler, upgrading pipework, or moving from system to combi typically takes two to three days. You're without hot water and heating for the working time, so we plan it around your week.
New showers and bathrooms paired with upgraded hot water flow and underfloor heating.
Learn more →Wiring for new boilers, immersions, smart thermostats and underfloor heating controls.
Learn more →Annual servicing, landlord checks and reactive heating call-outs.
Learn more →Free site visit, no obligation, all London areas.
Book Your Free Visit →These are typical London market ranges for 2026, not a fixed price list — your actual figure depends on boiler type, property size and how much pipework needs touching.
Ranges cover supply and Gas Safe installation labour for a standard London property. They exclude builder's work (boxing-in, making good, redecoration), flue or gas-supply upgrades, scaffolding for high-level flues, and any asbestos removal. A like-for-like boiler swap sits at the lower end; relocating the boiler, upgrading controls or full system replacement pushes towards the top.
A like-for-like combi swap is the cheapest job; converting regular to combi or adding a cylinder means extra pipework, controls and a longer install.
More bedrooms means more radiators, longer pipe runs and a bigger boiler output — a 3-bed full system costs far more than a 1-bed flat.
Moving the boiler or running a new flue adds £850–£1,150 in labour; loft or awkward flue positions need extra time and access.
Old, sludged or undersized pipework often needs replacing or a powerflush before a new boiler's warranty is valid, adding several hundred pounds.
Larger homes with multiple bathrooms need a system boiler plus an unvented mains-pressure cylinder, typically £1,000–£2,000 supplied and fitted.
Smart thermostats, TRVs and zoning add cost, while premium brands like Worcester or Vaillant carry longer warranties at a higher unit price.
Want an exact figure for your project? Book a free site visit → and we’ll send a written quote.