What to do when your boiler breaks down in winter
Four checks fix most winter boiler breakdowns without an engineer, and they take about ten minutes: pressure, frozen condensate pipe, power, reset. Work through them in that order before you call anyone. If the boiler still will not fire after all four, note the fault code on the display and get a Gas Safe engineer out. With us that is £80 for the first hour with no call-out fee, and most repairs are done inside it.
Before anything else: when to stop and call
Do not work through the checklist below, and call for help now, if any of these apply.
- You can smell gas. Turn the gas off at the meter, open windows, do not touch any electrical switch, and ring the National Gas Emergency Service on 0800 111 999. That is free, and it is a 24 hour line.
- A carbon monoxide alarm is sounding. Get everyone out into fresh air first, then ring the same number.
- Water is leaking from the boiler. Turn the boiler off and turn the water supply to it off if you can reach the valve.
- There is scorching, or black sooty marking, around the boiler case. Turn it off and leave it off.
Everything else on this page is safe for a householder to try.
Check 1: the pressure gauge
The most common thing you can actually fix yourself. Look at the gauge on the front of the boiler. Cold, it should read between 1 and 1.5 bar. Below 1 and most modern boilers will refuse to fire rather than run dry.
Topping it up takes two minutes. Find the filling loop, usually a braided silver hose underneath the boiler with a valve at each end. Open both valves slowly, watch the needle climb to about 1.2, then close both fully. The boiler will often fire on its own; if not, reset it (check 4).
If the pressure is above 2.5, there is too much water in the system. Bleeding a radiator will bring it down, and our guide to bleeding your radiators walks through it.
One thing worth knowing: if you find yourself topping the pressure up every few weeks, you have a leak. Topping it up is treating the symptom, and a small leak that goes unfound all winter does real damage to a system.
Check 2: a frozen condensate pipe
This is the single most common cause of a winter boiler breakdown, and the reason your boiler picked the coldest night of the year to stop. It is also completely free to fix.
Every modern condensing boiler produces acidic waste water, which drains away through a plastic condensate pipe. That pipe very often runs outside to a drain. When the temperature drops below freezing the water inside it turns to ice, the pipe blocks, and the boiler shuts itself down deliberately rather than back the waste up into itself. Many boilers show a specific fault code for it, almost always an ignition lockout rather than anything named after the pipe: EA / 227 on a Worcester Bosch, L2 on an Ideal, F.28 on a Vaillant.
How to thaw it:
- Find the pipe. It is plastic, usually white or grey, 22mm or 32mm, running from the boiler through an external wall down to a drain or gully.
- Pour warm water along it, concentrating on any bend, any low point, and the open end. Not boiling water: boiling can crack the pipe or split a fitting, and you have then turned a free fix into a paid repair.
- A hot water bottle or a hand warmer held against the blocked section works just as well and is gentler.
- You will often hear it gurgle as it clears.
- Reset the boiler. It should fire.
If it freezes again in every cold snap, the pipe is either too long outside, too narrow, or run without a fall. Lagging it properly or rerouting it internally is a small job, and worth doing once rather than thawing it out every January. We will do it while we are there.
Check 3: power, fuse and controls
Obvious, and worth thirty seconds. Has the fused spur next to the boiler been switched off? Has a fuse blown or an RCD tripped in the consumer unit? Has the thermostat run out of batteries, which is a genuinely common one and looks exactly like a dead boiler? Has the timer or programmer lost its schedule after a power cut, so the boiler is working perfectly and simply not being asked to fire?
Turn the thermostat well up and see whether the boiler responds. If it does, it was the controls, not the boiler. Our guide on getting control of your heating at home covers setting them properly once you are warm again.
Check 4: reset, once
Most boilers have a reset button. Press and hold it for up to ten seconds. You should hear it fire up, or see the fault code clear.
Reset it once, or at most twice. If it locks out again straight away, it is telling you something real and repeated resetting will not fix it. Write the fault code down instead. It is the most useful thing you can give an engineer on the phone, and it often means the right part comes out on the first visit. We keep plain-English guides to the codes for Worcester Bosch, Ideal, Vaillant and Baxi boilers.
What it costs to get someone out
If the four checks have not done it, this is where an engineer earns their money, and the honest numbers matter when you are cold and worried about the bill.
£80 for the first hour, with no separate call-out fee. That hour includes the diagnosis, and most repairs are finished within it. Parts, if any are needed, are quoted at trade price before we order them, and you decide whether to go ahead. If we cannot fix it on the first visit because the part is not on the van, we take 50 per cent of the first visit fee off the return visit. That is our first-time-fix promise, and it is why we carry the common parts.
We dispatch from Leeds Road in Bradford and hold same-day slots back through the winter across BD, LS, WF, HD, HX and HG. Book a boiler repair, or ring 0800 980 6018 and speak to someone in Bradford rather than a call centre.
Repair or replace?
The engineer will tell you which after the diagnosis, and the rough rule is this: if the boiler is under about ten years old and the repair comes in under roughly £600, fixing it is almost always the sensible call. Older than that, or a repair bill approaching the price of a new unit, and replacement is better value.
We quote both numbers at the same visit so you can compare like for like, and we put the £80 diagnosis fee towards the new installation if you go that way. Our signs you need a new boiler guide sets out what to watch for, and new boiler installation covers what a replacement costs.
Stopping it happening again
Almost every winter breakdown we attend was preventable, and the pattern is very consistent: the boiler had not been serviced, or the condensate pipe was never lagged.
An annual boiler service is £80 fixed and takes about an hour. It catches the flat expansion vessel, the blocked condensate trap and the sludged magnetic filter that would otherwise become a January no-heat call. It also keeps the manufacturer warranty valid, which on a boiler still under cover is worth far more than the £80. Book it in late spring or summer if you can, when engineers are not stretched.
If an unexpected repair bill would be hard to absorb, a Smart Care cover plan starts at £20 a month, includes the annual service, and carries no separate call-out fee and no surprise excess. If your boiler is newer and still under warranty you may only need the £80 service, and we will tell you that rather than sell you the plan.
Do not wait for the first cold snap
The busiest week of our year is the first hard frost, and every winter the same thing happens: the boilers that fail are the ones that were never serviced.
If yours has not been looked at in the last twelve months, get it booked now rather than in December. Book an £80 boiler service online in about two minutes, or if you are cold right now, book a repair or call 0800 980 6018.
Prices and the first-time-fix terms checked 7 September 2026.