DIY Checks & Simple Fixes

No power to the boiler

• Check the boiler itself — some have a power button or switch that can be knocked off accidentally.
• Check the fuse spur next to the boiler — it may have been switched off. It looks like a small switch on the wall, usually within a metre of the boiler.
• Check the consumer unit (fuse board) — the boiler's breaker may have tripped. Bear in mind that a tripped breaker might indicate an underlying electrical problem.

Boiler losing pressure / how to repressurise

• Low pressure looks like the gauge reading below 1 bar — the boiler may lock out or show an error code.
• To repressurise: some boilers have a traditional external filling loop (a braided hose between two valves under the boiler), others have a lever or mechanism built into the boiler itself. A quick Google of your make and model usually shows you how yours works.
• Aim for about 1.5 bar — it doesn't need to be exact.
• Once repressurised, most boilers will automatically reset themselves and just start working again.

Frozen condensate pipe

• This is common in cold weather. The boiler locks out, often with a gurgling sound or a specific error code.
• The condensate pipe is a thin plastic pipe (usually white or grey) running from the boiler to an outside drain, often along an outside wall or through an unheated space like a garage.
• To thaw it, pour warm water (not boiling) over the frozen section of the pipe. A kettle of warm water, a hot water bottle, or a warm cloth wrapped around it usually does the job.
• Once thawed, reset the boiler and it should fire up again.

Boiler showing an error code

• The very first thing to do is make a note of the error code.
• Try resetting first — find the reset button on the front of the boiler (it's usually clearly marked) and hold it for 3–5 seconds.
• If the boiler fires up and stays on, it was probably a one-off. Keep an eye on it.
• If it locks out again, note down the error code again before you call us — it speeds up diagnosis.

Radiator cold at the top

This usually means there's air trapped in the radiator. Bleeding it lets the air out so hot water can fill the whole radiator again.

• You'll need a radiator key (available from any hardware shop for about £1) and a small towel.
• Turn the heating on so the radiators are warm — this helps you feel when you've bled enough.
• Find the bleed valve at the top corner of the radiator. Insert the key and turn anti-clockwise slowly.
• You'll hear air hissing out. Hold the towel underneath. When water starts to dribble out steadily, close the valve — job done.
• Check your boiler pressure afterwards — bleeding radiators can drop it slightly. Top up if needed (see above).

Thermostat or timer not doing what you expect

• Check the batteries — wireless thermostats run on batteries, and when they go flat the thermostat stops communicating with the boiler.
• Check the clock is set right — the clocks going forward or back catches everyone out. Some programmers need resetting manually.
• Check it's in the right mode — some thermostats have holiday, away, or frost-protection modes that can confuse things if they've been activated accidentally.