Doncaster · BPHS
Frozen condensate pipe — boiler off in the frost
Straight answer
If your boiler cuts out in freezing weather in Doncaster, the white plastic condensate pipe outside is often frozen. Pour warm — not boiling — water along the pipe to thaw it, then reset the boiler once. Lag the pipe afterwards. If it freezes every cold night, the run is too shallow or too long: we can reroute or upsize it.
How to thaw a frozen condensate pipe
- Step 1. Find the white or grey plastic pipe from the boiler to an outside drain or soakaway.
- Step 2. Pour warm water (from a kettle that has sat a minute — not boiling) slowly along the pipe.
- Step 3. Wait a few minutes and reset the boiler once.
- Step 4. If it fires, wrap the pipe with proper outdoor lagging.
- Step 5. If it will not reset, or ice is inside the trap, stop and call a Gas Safe engineer.
A proper fix
If this is a yearly ritual, we shorten the external run, increase the pipe diameter, or take it internally to a waste. That is a small job compared with a week of no heat.
People also ask
Why does my boiler only break in cold weather?
Condensate from modern condensing boilers can freeze in an exposed pipe. The boiler then locks out on a blockage. It looks like a ‘broken boiler’ and often is not.
Can I use boiling water or a hairdryer?
Boiling water can split plastic. A hairdryer is slow and awkward outside. Warm water along the pipe is the usual fix. Do not take the boiler case off.