Central Heating & Gas Work · All 32 London boroughs
Heating Engineers in London: Boilers, Radiators and Gas Work
Most London heating problems come down to the city itself: hard water scaling up combi boilers, old systems full of sludge that nobody has flushed, condensate pipes that freeze in the first cold snap, and flats where the flue route depends on the freeholder. Soraiz Builders installs, repairs and services boilers, fits radiators and controls, power-flushes systems and lays underfloor heating. All gas work is carried out by Gas Safe registered engineers, and we reply to every enquiry within 2 hours.
Quick answer: 2026 prices
A like-for-like combi boiler replacement typically costs £1,800 to £3,500 fitted, with a median quote of about £2,300. In London, an annual boiler service costs about £90 to £150, a typical repair £200 to £500, and a service with a landlord gas safety certificate £110 to £180.
If you smell gas, leave the property and call the National Gas Emergency Service on 0800 111 999 first. For everything else, we reply within 2 hours during business hours.
- Founded 2019
- 250+ London projects
- MyBuilder 5.0 from 23 verified reviews
- Gas Safe registered engineers
Repair or replace?
Should you repair your boiler or replace it?
Repair a boiler that is under about 10 years old with a one-off fault; start pricing a replacement when it is older, breaking down repeatedly, or the repair quote is a large share of a new one. Tick what applies and the box below gives you a starting point.
Nothing ticked yet.
Boiler not working? Check these first
- Pressure gauge between 1 and 1.5 bar when cold
- Thermostat and timer calling for heat
- Power on at the fused spur
- Gas on at the meter and other gas appliances working
- In freezing weather, a frozen condensate pipe outside
- The fault code noted for the engineer
What we do
What heating and gas work do we carry out in London?
Six kinds of heating work, with every gas job done by a Gas Safe registered engineer. Leaks, water pressure and unvented hot water cylinders are covered on our Plumbing in London page.
Boiler installation and replacement
New combi, system and regular boilers, like-for-like swaps and conversions, such as a regular boiler and tanks to a combi, including moving the boiler.
- Combi, system and regular
- Conversions and relocations
- Building Regulations certificate
Boiler repairs
Breakdowns diagnosed and fixed: no heat or hot water, pressure loss, leaks, fault codes, ignition problems and frozen condensate pipes.
- Fault finding
- Parts replaced
- Repair or replace advice
Servicing and gas safety certificates
Annual boiler services that keep the manufacturer’s warranty valid, and landlord gas safety records (CP12) for every gas appliance in a let property.
- Annual services
- Landlord CP12 records
- Carbon monoxide alarm checks
Radiators and power flushing
New, replacement and moved radiators, including column and designer styles, and systems power-flushed to clear sludge before or after a new boiler.
- New and moved radiators
- Power flushing
- Magnetic filters
Heating controls
Smart and programmable thermostats, thermostatic radiator valves and zoning, set up so the heating runs only where and when you need it.
- Smart thermostats
- TRVs and zoning
- Boiler Plus compliant controls
Underfloor heating
Wet underfloor heating connected to the boiler for extensions and ground floors, and electric mats for bathrooms and kitchens.
- Wet systems and manifolds
- Electric mats
- Floor finish advice
Every new boiler installation includes
- Gas work by a Gas Safe registered engineer
- The system cleaned and treated with inhibitor
- A scale reducer, as London’s hard water requires
- Controls that meet the Boiler Plus rules
- A carbon monoxide alarm, as the Building Regulations require
- Registration, Building Regulations certificate and warranty paperwork
2026 costs
How much does a new boiler or heating work cost?
A like-for-like combi boiler replacement typically costs £1,800 to £3,500 fitted in 2026, with a median quote of about £2,300, and conversions or relocations cost more.
The tables below are typical market ranges, not fixed Soraiz Builders prices. Every job is priced in writing before work starts.
New boilers
| Job | Typical cost | Notes |
|---|---|---|
| Like-for-like combi swap | £1,800–£3,500 | Median quote about £2,300; most £2,150–£3,000 |
| Premium combi | £3,000–£4,500 | Higher-end brands and longer warranties |
| System boiler replacement | £1,800–£3,500 | Cylinder work extra if needed |
| Back boiler conversion | £3,500–£6,000 | Old fireplace back boilers removed and replaced |
| Conversion or relocation | Above a swap | New pipework, flue route and making good |
Sources: Heatable new boiler costs (2026, based on 2,000 quotes from January to June 2026; UK figures, London costs more). Typical market ranges, not fixed Soraiz Builders prices.
Servicing and repairs
| Job | Typical London cost | Notes |
|---|---|---|
| Annual boiler service | £90–£150 | Gas combi about £90–£130 |
| Service plus gas safety record (CP12) | £110–£180 | For landlords |
| Minor repair | £150–£300 | Thermostat, sensor, valve or seal |
| Average repair | £200–£500 | Fan, pump, circuit board or diverter valve |
| Major repair | £450–£850+ | Heat exchanger or major leak; often time to replace |
| Emergency or out of hours | £150–£400 | Plus parts |
| Frozen condensate pipe | £80–£200 | UK figure; rerouting or insulating stops repeats |
Sources: Fantastic Services boiler service and boiler repair cost guides (2026, London and South East column). Typical market ranges, not fixed Soraiz Builders prices.
Radiators, flushing and underfloor heating
| Job | Typical cost | Notes |
|---|---|---|
| Power flush, 1 to 2 bed | £400–£470 | 6–8 radiators |
| Power flush, 3 bed | £470–£520 | 8–10 radiators; London 20–30% more |
| Magnetic system filter | £180–£260 | Fitted |
| Replace radiator valves | £75–£180 | Per job |
| Fit a new radiator | £250–£400 | Straightforward swap or install |
| Move a radiator | About £275 | New pipework runs £350–£700 |
| Wet underfloor heating, retrofit | £80–£150 per m² | Screed often quoted separately |
| Electric underfloor heating | £40–£90 per m² | Installed, before the floor finish |
Sources: MyJobQuote power flush costs (September 2026) and radiator installation costs (2026), Fantastic Services power flush guide (London uplift), Book A Builder UK and Trade2Base underfloor heating costs (2026). Typical market ranges, not fixed Soraiz Builders prices.
Heating inside a bigger project is priced as part of it. See the Combi vs System Boiler guide if you are deciding which type suits your home.
Rules
Which rules apply to boilers and gas work?
Only a Gas Safe registered engineer may work on a gas boiler or appliance, and a new boiler has to meet efficiency, controls, water treatment and carbon monoxide alarm rules.
- Gas Safe registration: it is a legal requirement under the Gas Safety (Installation and Use) Regulations 1998. Ask to see the engineer’s Gas Safe ID card and check the back: it lists the categories they are qualified for, so an engineer qualified only for cookers cannot work on a boiler. You can confirm registration on the Gas Safe Register website. Gas Safe Register estimates around 250,000 illegal gas jobs a year, and has found around two thirds of the illegal gas work it inspected to be unsafe.
- Boiler Plus: since April 2018, a new or replacement gas boiler in England must be at least 92% efficient (ErP) and have time and temperature controls. A combi also needs one extra energy-saving measure: weather compensation, load compensation, smart controls with automation and optimisation, or flue gas heat recovery.
- Hard water: where mains water is harder than 200 ppm, the hot water side of a combi must be treated to slow limescale, usually with a scale reducer. All of London’s Thames Water area is hard water.
- Carbon monoxide alarms: since 1 October 2022, a CO alarm must be fitted in the room when a new or replacement gas boiler or other fixed combustion appliance (except a cooker) is installed.
- Landlords: every gas appliance in a let property needs a gas safety check at least every 12 months. Keep the record for two years, give tenants a copy within 28 days, and give new tenants one before they move in.
- Flats and flues: a new flue through an external wall in a leasehold flat usually needs the freeholder’s consent, and flues must be positioned clear of windows, doors and boundaries. Some older blocks have shared flue systems that limit which boilers can be fitted.
- Heat pumps: replacing a gas boiler in an existing home is still allowed. If you are considering a heat pump instead, the government’s Boiler Upgrade Scheme offers up to £7,500 towards one.
London homes
What heating problems do London homes have?
The type of home decides which boiler suits it and what usually goes wrong.
Victorian and Edwardian terraces
Often converted from old regular boilers and loft tanks, with long pipe runs, sludged-up radiators in cold back rooms, and the occasional back boiler behind a fireplace.
1930s semis
Regular or system boilers with a hot water cylinder. With two bathrooms in use at once, a system boiler and cylinder often beats a combi.
Flats
Combis are the usual choice for space. Flue positions, freeholder consent and shared flues in older blocks shape what can be fitted and where.
Everywhere in winter
Condensing boilers drain condensate outside, and a thin, long external pipe can freeze in a cold snap and stop the boiler. Short, insulated runs of at least 32 mm prevent it.
Recent Central Heating & Gas Work projects
Real jobs that included this work, documented from the dated photos taken on site.
22 photosBlendon, Sidcup (Bexley)
Whole-home renovation in Blendon, Sidcup
A Sidcup home taken back to bare walls and finished as new over about 13 weeks: re-plastered throughout, a new kitchen and boiler, a new tiled bathroom, new flooring, decoration and a cleared garden.
Read the case study
Surrey Docks, Rotherhithe (Southwark)
Lighting, sockets and a new radiator in Rotherhithe
Hallway pendant lights rewired and fitted, a faulty socket replaced, and a new anthracite column radiator installed.
How it works
What happens when you book a heating engineer with us?
Tell us what is happening
Send the boiler make, its age if you know it, any fault code and your postcode. For a new boiler, photos of the boiler, flue and cylinder help.
Survey or diagnose
A Gas Safe registered engineer checks the system, the gas supply, the flue route and water pressure, and finds the fault or sizes the new boiler.
Written price
You get a price for the repair or a quote listing the boiler, controls, flushing, filter and any pipework, before work starts.
Install or repair
The work is done, the system cleaned and treated, and the boiler commissioned and tested, including a flue gas check.
Paperwork and handover
You get the commissioning checklist, Building Regulations certificate and warranty registration for a new boiler, or the service or CP12 record, and a walk-through of the controls.
Which boiler?
Combi, system or regular: which boiler suits your home?
A combi suits most flats and homes with one bathroom; a system boiler with a cylinder suits homes where two showers run at once; a regular boiler is mainly kept where the existing tanks and pipework favour it. Combis heat water on demand and need decent mains pressure, which is worth checking in older London streets. System boilers store hot water in a cylinder, often an unvented one fitted by a G3-qualified installer. Our Combi vs System Boiler guide compares them in detail.
How to choose a heating engineer in London
- A Gas Safe ID card covering boilers, checked online
- A written quote listing boiler, controls and flushing
- A scale reducer and filter included
- Warranty registration handled for you
- Public liability insurance
- Recent reviews you can check
Questions
Heating and gas work in London: frequently asked questions
How much does a new boiler cost in London?
A like-for-like combi boiler replacement typically costs £1,800 to £3,500 fitted in 2026, with a median quote of about £2,300 across 2,000 UK quotes, and London at the upper end. Premium combis run £3,000 to £4,500. Converting from a regular boiler, moving the boiler or replacing a back boiler costs more, from about £3,500 to £6,000.
How much does a boiler service cost in London?
An annual boiler service in London typically costs £90 to £150 in 2026, around £20 to £40 more than elsewhere in the UK. Landlords usually pay £110 to £180 for a service combined with the gas safety record. Most manufacturers require a yearly service by a Gas Safe registered engineer to keep the boiler’s warranty valid, so keep the paperwork.
Should I repair or replace my boiler?
Repair it if it is under about 10 years old and the fault is a one-off, such as a pump, valve or sensor. Consider replacing it if it is over 12 to 15 years old, has broken down repeatedly, or needs a major part such as a heat exchanger, which can cost £450 to £850 or more in London. A new boiler is also more efficient.
What do landlords need for gas safety?
A gas safety check of every gas appliance and flue at least every 12 months by a Gas Safe registered engineer, often called a CP12. Landlords must keep each record for two years, give existing tenants a copy within 28 days and new tenants one before they move in. A carbon monoxide alarm is also needed in rooms with a fixed combustion appliance.
Why does my boiler keep losing pressure?
Usually a small leak somewhere in the system, a failing expansion vessel, or a pressure relief valve letting water out through its pipe outside. Topping the pressure back up to about 1 to 1.5 bar is fine occasionally, but if it drops again within days, have it checked. In London, a low-pressure repair typically costs £150 to £350.
What should I do if my condensate pipe freezes?
Find the plastic pipe running from the boiler to an outside drain and pour warm, not boiling, water along it, or hold a hot water bottle on the frozen section, then reset the boiler. If it happens every winter, the pipe should be rerouted or upsized to at least 32 mm and insulated, which stops it freezing in the next cold snap.
Do I need a power flush?
Possibly, if radiators are cold at the bottom, the boiler is noisy, or bled water comes out dark. A power flush clears sludge and typically costs £400 to £520 for a home of up to three bedrooms, more in London. A new boiler needs the system cleaned first, and a magnetic filter, about £180 to £260, keeps it clean afterwards.
Is a combi or system boiler better?
A combi suits most flats and homes with one bathroom, because it heats water on demand and needs no cylinder or tanks. A system boiler with a hot water cylinder suits larger homes where two or more showers run at the same time. A combi relies on good mains pressure, so it is worth checking the flow rate before choosing one.
Verified reviews
What London clients say about Soraiz Builders
★★★★★
“Was very professional and polite, communicated clearly throughout the process, including a clear quote and what was included in the work.”
Victoria, Watford · Plaster wall repair · May 2025
★★★★★
“Soraiz was excellent! He is professional,and efficient. Fast response and did a great job.”
Wahid Rakesh, Holloway · Handyman work · April 2024
★★★★★
“Very good reliable builders, excellent service. Quality and reliable competitive prices. Had a re visit after 1 month of finishing work and rectified slight issues free of charge.”
Azhar, Islington · Rooms and staircase painted · December 2024
Rated 5.0 from 23 verified reviews on MyBuilder. These reviews reflect Soraiz Builders’ wider portfolio of work across London, not heating jobs specifically.
Get started
Get a free heating quote in London
Send the boiler make, age and any fault code, or photos of the boiler and flue for a replacement, with your postcode. We reply within 2 hours during business hours and give you a written price before work starts.
- Founded 2019
- 250+ London projects
- Gas Safe registered engineers
- All 32 boroughs