Heating Problems
No Heating in Winter? What To Do Right Now
Reviewed by our Gas Safe registered engineers · Last updated 21 July 2026
Losing heat in cold weather is stressful — especially with children or older people at home. Here’s what to check immediately, the most common winter causes (frozen condensate is top of the list), and how to get help fast.
Quick answer: In winter, the number one cause of sudden heat loss is a frozen condensate pipe — the external white pipe blocks with ice and the boiler locks out. Thawing it often restores heat. Also check pressure, the programmer and the thermostat. If anyone at home is vulnerable and it’s very cold, treat it as urgent.
First Steps
Common winter causes and what to do
Work through these quickly. The colour on the left shows whether it’s a safe check you can do now or a job for an engineer.
| What’s happening | Likely cause | What to do |
|---|---|---|
| Boiler locked out on a cold morning | Frozen condensate pipe | Thaw the external white pipe with warm water, then reset |
| Low pressure warning showing | Pressure dropped in the cold | Repressurise to ~1.3 bar via the filling loop |
| No response at all | Power or programmer | Check the fused spur and programmer settings |
| Heating won’t come on | Thermostat not calling | Turn it up; check the batteries and mode |
| Radiators cold, boiler running | Trapped air or circulation | Bleed the radiators; check the pump |
| Repeated lockouts in the cold | Ignition or gas fault | Book a Gas Safe engineer |
Safe Checks
What you can do right now
Safe to do
- Thaw a frozen condensate pipe with warm (not boiling) water, then reset
- Check the pressure gauge and top up to ~1.3 bar if low
- Confirm the programmer is set to come on and the thermostat is calling
- Bleed radiators that are cold at the top
Urgent — call us now if…
- Someone at home is elderly, very young or unwell and it’s very cold
- You can smell gas — leave the property and call 0800 111 999
- The boiler keeps locking out after thawing and resetting
Engineer Insight
What we usually find
Winter call-outs are overwhelmingly frozen condensate pipes — a five-minute fix once you know. If thawing the pipe and topping up pressure doesn’t restore heat, or anyone at home is vulnerable in the cold, don’t wait: we keep emergency slots for exactly this, and can talk you through the safe checks on the phone.
Costs
What winter repairs typically cost
Typical North London guide prices — you’ll always get an upfront quote before any work starts.
FAQs
No heat in winter — your questions answered
Why do boilers stop working in cold weather?
The most common reason is a frozen condensate pipe — the external white waste pipe freezes and blocks, so the boiler locks out for safety. Thawing it usually restores heat.
How do I thaw a frozen condensate pipe?
Pour warm (not boiling) water over the external white pipe, or hold a wrapped hot water bottle against it. Once thawed, reset the boiler. If you can’t reach the pipe safely, call us.
My heating’s off and it’s freezing — is it an emergency?
If anyone at home is elderly, very young or unwell, or if you can smell gas, treat it as urgent and call us for a priority visit. We keep emergency slots for winter heat loss.
Can I stop my condensate pipe freezing again?
Insulating the external pipe with foam lagging helps a lot. An engineer can also advise on re-routing or upsizing it if it freezes repeatedly.
What should I check first when the heating fails in winter?
The external condensate pipe (frozen?), the pressure gauge (top up to 1.3 bar), and the programmer and thermostat (set to come on, with fresh batteries).
Related
Keep troubleshooting
What to do first if you’ve lost heat or smell gas.
Read guideBoiler ProblemsBoiler Not Turning OnIf there’s no response at all from the boiler.
Read guidePressureHow to Repressurise a BoilerClear a cold-weather low-pressure lockout.
Read guideHeatingHeating Not WorkingThe full year-round troubleshooting guide.
Read guidePressureLow Boiler PressureWhy pressure drops in the cold and how to fix it.
Read guideHeatingHeating Problems HubAll our heating and radiator guides in one place.
Browse guidesBrowse all Heating Problems guides, or head back to the Help & Advice Centre.
Cold home, no heat? Call us now.
We keep 24/7 emergency slots for winter heat loss across North London. Call and we’ll talk you through the safe checks — and get an engineer to you if you need one.
Gas Safe Registered 918817 | 24/7 emergency cover | North London specialists