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Central heating repairs in London cost £120 to £420 for most faults, plus a £60 to £125 call-out that many firms waive if you go ahead. Labour is £80 to £140 an hour. A pressure fault is £120 to £280, a diverter valve £150 to £390 and a circulation pump £180 to £420, part included.
| Job | London low | London typical | London high | UK typical | What moves the price |
|---|---|---|---|---|---|
| Call-out and diagnosis, weekday | £60 | £120 | £125 | £80 | Often waived if you go ahead with the repair; one firm's fee covers the first 45 minutes |
| Labour, per hour | £80 | £110 | £140 | £70 | £140 and up out of hours |
| Out-of-hours or emergency, first hour | £140 | £180 | £260 | Saturday, evening, then Sunday and bank holiday, in rising order | |
| Pressure loss, expansion vessel or pressure relief valve | £120 | £200 | £280 | The most common winter fault | |
| Circulation pump | £180 | £300 | £420 | Boiler fires but radiators stay cool; a tight cupboard adds time | |
| Diverter valve | £150 | £280 | £390 | Heating works but no hot water, or the reverse | |
| Magnetic filter, supplied and fitted | £150 | £195 | £240 | £220 | Catches sludge before it reaches the boiler; London's hard water makes it standard |
| Power flush, 8 radiators | £580 | £680 | £800 | £495 | £60 to £85 per radiator; Zones 1 and 2 add 10 to 15 per cent; well under £50 a radiator usually means corners cut |
Diagnosis comes first. The engineer reads the pressure gauge, checks the pump, valves and controls, reads any fault code and quotes the part before fitting it. Most London firms waive the call-out fee if you go ahead. Pressure faults and valves are the cheap end, pumps and diverter valves the middle; faults inside the boiler itself belong on the boiler repairs page.
Cold radiators, a system that needs topping up every week and a boiler that fires but heats nothing are the usual calls. London's water is hard, 250 to 350 mg/L of calcium carbonate, so sludge and scale build quickly, and a magnetic filter or, in older systems, a power flush is a common recommendation. Historic pipework and tight cupboards in older London housing add time.
Before you book: reset the boiler once, read the pressure gauge, check the thermostat and timer, and check the heating switch on the fuse board. Do not open the boiler casing or touch the gas side; that is Gas Safe registered work. Flushing a system is not gas work, but disconnecting the boiler to do it is.
Prices last checked: September 2026. Based on the published 2026 repair, call-out and power flush prices of four London heating firms, MyJobQuote's 2026 guides and Checkatrade snippets. PROS AI does not yet have enough completed central heating repairs in London to publish its own averages.
£120 to £420 for most faults including the part, plus a £60 to £125 call-out that many firms waive if the repair goes ahead. Labour is £80 to £140 an hour, £140 and up out of hours. A pressure or expansion vessel fault is £120 to £280, a diverter valve £150 to £390, a circulation pump £180 to £420 and a magnetic filter £150 to £240 fitted.
£140 to £260 for the first hour out of hours, against £60 to £125 in the daytime. One London firm charges £120 for the first hour on a weekday, £160 on a Saturday, £180 in the evening and £220 on a Sunday or bank holiday. If the house is not cold and nothing is leaking, a weekday morning booking saves most of the premium.
A magnetic filter, £150 to £240 fitted in London, catches sludge from now on; a power flush, £450 to £620 for six radiators and £580 to £800 for eight, clears what is already there. Manufacturers require the system to be flushed and inhibited when a new boiler goes in or the warranty is at risk. A quote well below £50 a radiator usually means corners cut.
Four things, none of which open anything: reset the boiler once; read the pressure gauge and note the number; check the room thermostat and the timer are on and calling for heat; check the heating switch on the fuse board. If it trips again or the pressure keeps dropping, book an engineer. Only a Gas Safe registered engineer may open the boiler or work on the gas supply.
If the fault is inside the boiler, such as the fan, the circuit board, the heat exchanger or the ignition, it is a boiler repair. If it is the system around it, the pump, the valves, pressure, sludge or a radiator, it is central heating. London heating firms quote both at the same £80 to £140 an hour, so book whichever matches your symptom and the engineer sorts out the rest.
Written by Shay Hazan, PROS AI.
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