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Complete boiler, heating & gas services
One trusted team for everything from a new boiler to an emergency leak across every London borough.
Boiler Installations
New combi, system and regular boiler installs from Baxi & Vaillant usually completed in a day.
Get a quoteBoiler Repairs
Fast diagnosis and repair of breakdowns, leaks, pressure loss and error faults same-day where possible.
Book a repairGas Certificates (CP12)
Landlord gas safety certificates and appliance checks booked quickly and issued the same day.
Arrange nowPower Flush
Remove sludge and restore circulation for warmer radiators, lower bills and a longer boiler life.
Learn moreCentral Heating
Full system design, radiator upgrades, smart controls and underfloor heating from specialists.
ExploreGas Leak Detection
Urgent leak detection and made-safe callouts. If you smell gas, we respond fast day or night.
Emergency helpOur Customer Reviews On Google
Diamond Gas replaced our old boiler with a new Vaillant in a single day. Spotless work, clearly explained, and cheaper than two other quotes. Genuinely faultless.
Read moreBoiler died on a Sunday with a newborn in the house. They came out same day, diagnosed it and had us back up and running within hours. Absolute lifesavers.
Read moreAs a landlord with 9 properties I need reliable engineers. Gas certs are always done on time and their reporting is brilliant. My go-to team in London.
Read moreYour questions, answered
Everything you need to know about boilers, pricing and our service.
A new combi boiler installation in London typically ranges from £1,900 to £3,500, depending on the brand, boiler size and how complex the installation is. Use our instant quote tool above for a tailored, no-obligation price in under 90 seconds.
Yes — absolutely. Every Diamond Gas engineer is Gas Safe registered, fully insured and manufacturer-accredited by Baxi and Vaillant. We're happy to show our registration on arrival.
Yes. We offer same-day emergency callouts across London for boiler breakdowns, no heating, no hot water and suspected gas leaks. Call 07534 652448 and we'll prioritise you.
New installations come with up to a 10-year manufacturer warranty on Baxi and Vaillant units, plus our own workmanship guarantee. We register the warranty for you so you're covered from day one.
Most standard boiler swaps are completed within a single day. After your survey we can often install within 24–48 hours — sooner in an emergency.
Yes — we offer flexible finance options so you can spread the cost of a new boiler into affordable monthly payments. Ask our team for details when you request your quote.