The short version
- Check power, programmer, thermostat batteries and pressure before booking
- In a cold snap, a frozen condensate pipe is the single most common cause
- A fault code on the display is worth writing down before you reset
- Never remove the boiler casing or touch any gas fitting yourself
Start with the controls, not the boiler
More dead heating calls are caused by controls than by the appliance. Work through these in order and you will either fix it or rule it out.
- Is the programmer or timer actually calling for heat, and is the clock right after a power cut
- Room thermostat set above room temperature, and fresh batteries fitted
- Any smart thermostat still paired with its receiver
- Fused spur next to the boiler switched on, and the consumer unit not tripped
- Other gas appliances working, which tells you the gas supply is on
- Prepayment meter still in credit
Check the pressure gauge
If the gauge sits near zero, most modern boilers refuse to fire at all as a protection measure. Repressurising a combi through the filling loop is a job a householder can do safely, and it is covered step by step in our repressurising guide. If the pressure falls again within days you have a leak or a failed expansion vessel rather than a one off drop.
Cold weather: suspect the condensate pipe
If the heating died overnight during a freeze and the boiler is gurgling or showing a lockout, the plastic waste pipe running outside has almost certainly frozen. Thawing it with warm, not boiling, water along its outside run often brings the boiler straight back. Only do this if the pipe is safely reachable from the ground.
Note the fault code before you reset
Write down whatever the display shows. One reset is reasonable. Repeated resets on the same code hide the fault and tell the engineer nothing. The code plus the make and model usually decides which parts we bring with us.
Where it stops and needs a Gas Safe engineer
Anything behind the casing is ours, not yours. Fans, gas valves, ignition electrodes, diverter valves, pumps, printed circuit boards and any smell of gas all need a Gas Safe registered engineer. If you smell gas, turn the supply off at the meter, open windows, avoid switches and call the National Gas Emergency Service on 0800 111 999 before you call us.
Common questions
I have no heating and no hot water, is it an emergency?+
It is urgent rather than dangerous in most cases. If you smell gas, or the boiler is leaking water onto electrics, treat it as an emergency and isolate the supply first.
Why did it fail after a power cut?+
Programmers and some boilers lose their schedule when power is restored. Reset the clock and the heating times before assuming a fault.
How many times can I press the reset button?+
Once. If it locks out again, stop and book an engineer, because repeated resets can hide a genuine safety fault.
Will you come out the same day?+
We prioritise no heat and no hot water calls, especially for elderly customers and families with young children. Call and we will tell you honestly what we can do.
Could it just be the thermostat?+
Frequently, yes. Flat batteries and a lost wireless pairing are two of the most common causes we attend.
Still cold after those checks?
Tell us the fault code and what you have already tried and we will bring the likely parts.