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An emergency boiler engineer in London costs £140 to £260 for the first hour outside working hours, then £110 to £140 an hour, and most breakdowns are fixed for £200 to £600 including the part. A daytime visit is £60 to £125, so the three checks below are worth two minutes before you call anyone out.
| Job | London low | London typical | London high | UK typical | What moves the price |
|---|---|---|---|---|---|
| Out-of-hours first hour, weekday evening or Saturday | £140 | £180 | £260 | £450 | Checkatrade puts a UK emergency at £225 to £675 all in |
| Sunday or bank holiday, first hour | £180 | £220 | £260 | ||
| Each further hour, out of hours | £110 | £140 | £160 | ||
| Daytime call-out for comparison | £60 | £120 | £125 | £80 | Usually waived if the repair goes ahead |
| Pressure loss, expansion vessel or valve | £120 | £200 | £280 | The most common cold-snap fault | |
| Fan | £200 | £300 | £420 | £275 | |
| Circuit board (PCB) | £290 | £450 | £650 | £350 | |
| Heat exchanger | £450 | £650 | £880 | £425 | Replace the boiler if it is over 12 to 15 years old |
A breakdown is an emergency when there is no heating or hot water with young children, older or ill people in the home, when the boiler is leaking water, when a carbon monoxide alarm sounds, or when you smell gas. Gas comes first: leave the property, call the National Gas emergency line on 0800 111 999, and no engineer touches the boiler until the gas side is cleared.
For everything else, two minutes of checks can save a £200 call-out. Look at the pressure gauge: below 1 bar, top it up with the filling loop to between 1 and 1.5 bar. In a cold snap, a frozen condensate pipe is the most common cause of a boiler locking out; pouring warm, not boiling, water over the outside pipe and pressing reset once clears it. Check the thermostat and timer, and a prepayment meter if you have one. If none of that works, or the boiler trips again, stop there.
The engineer diagnoses from the fault code, quotes the part and fixes it on the spot where the part is on the van; a circuit board or heat exchanger can mean a second visit. London's cold weeks stretch a thin trade: 3.2 registered engineers per thousand households.
Prices last checked: September 2026. Based on the published 2026 emergency and out-of-hours tariffs of four London heating firms and Checkatrade's UK emergency snippet. PROS AI does not yet have enough completed emergency call-outs in London to publish its own averages.
£140 to £260 for the first hour on a weekday evening or a Saturday, £180 to £260 on a Sunday or bank holiday, then £110 to £160 an hour. With a typical part the bill lands at £200 to £600. The same fault on a weekday morning is £60 to £125 for the visit.
Three things, all safe: the pressure gauge (top up to 1 to 1.5 bar with the filling loop if it is low), the condensate pipe outside if it is freezing (warm water, then one reset), and the thermostat, timer and any prepayment meter. Do not open the boiler casing or keep pressing reset; if it locks out twice, call.
Leave the property, do not switch anything on or off, and call National Gas on 0800 111 999 from outside. They make the gas safe for free. Only after that does a Gas Safe engineer look at the boiler.
Usually. Pressure faults, valves, ignition parts and most fans and pumps are on the van and done in the first hour or two. A circuit board or a heat exchanger for a specific model may need ordering, so the engineer makes the boiler safe and returns; ask for the part price before agreeing.
Yes, by £80 to £150 on the visit alone, and the repair itself costs the same. If nobody in the home is vulnerable and there is no leak or gas smell, a morning slot at £60 to £125 is the sensible call. Keep the heating off, not just the thermostat down, until the engineer arrives.
Written by Shay Hazan, PROS AI.
£150 - £700per job
A guide range for this kind of job, based on London market rates. It is not a quote - the quotes your pros give you are the real answer, and they are free.
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