Boiler Breakdown? Here's Exactly What to Do Before the Engineer Arrives
No heating, no hot water, or a boiler that won't stop locking out — the safe checks to make first, and when to stop and call an emergency engineer.
A boiler that won't fire on a cold morning is more than an inconvenience — with young children, elderly relatives, or anyone vulnerable in the house, it's a genuine problem worth taking seriously. Here's exactly what to check in the first few minutes, before you call anyone.
1. Check the pressure gauge
If the needle's below 1 bar, most modern combis will lock out and refuse to fire. Nearly every boiler has a filling loop — usually a braided hose underneath — that lets you top up to around 1.2 bar yourself in a couple of minutes. If it drops again within a day or two, you likely have a leak somewhere in the system, which needs a proper look rather than repeated topping up.
2. Look for a fault code
The digital display will usually show something like F22, E133 or A21. Photograph it and read it out when you call — a lot of the time we can tell you what's likely wrong before we even arrive, which means turning up with the right part rather than needing a second visit.
3. Reset once — never repeatedly
Press the reset button once, wait two minutes. If it locks out again, stop. Repeated resets on an ignition or overheat fault can turn a straightforward sensor repair into a full PCB replacement.
4. Smell gas? Stop everything
If you smell gas: don't touch any electrical switches, open the windows, turn the gas off at the meter, leave the property, and call the National Gas Emergency Service on 0800 111 999 immediately. Call us once the supply's confirmed safe.
5. Call an engineer
If none of the quick checks fix it, or if you've already reset once without success, it's time to call. Genuine emergencies — no heating or hot water in cold weather, especially with vulnerable people in the house — get priority same-day attention from us.
Prevention is cheaper than the emergency call-out
The large majority of the breakdowns we attend could have been caught at an annual service — a seized pump, a blocked condensate trap, a sticking diverter valve, all show up in a routine check months before they cause a genuine breakdown.