Boiler Breakdown in Cold Weather: What to Do While You Wait for an Engineer

First: Work Through the Basic Checks

Before accepting that you need an engineer, spend five minutes on the checks that most commonly resolve a winter boiler stoppage without a call-out. A significant proportion of winter "boiler breakdown" calls turn out to be a resolvable issue.

• Check the boiler pressure gauge — if it reads below 1 bar, the boiler has locked out due to low pressure. Repressurise to 1–1.5 bar using the filling loop and press reset. Our repressurising guide walks through the process step by step.
• Check for a fault code — is the boiler displaying letters or numbers? See our boiler error codes guide — some codes indicate conditions you can resolve yourself.
• Check the condensate pipe — if the temperature outside is below freezing, the external condensate pipe may have iced up. This is one of the most common winter boiler lockouts. Thaw the visible external section with warm (not boiling) water and reset the boiler.
• Check the thermostat and programmer — has the heating schedule been cleared by a power cut? Is the room thermostat set above the current room temperature? Try switching heating to continuous and turning the thermostat to maximum.
• Check whether neighbours have gas — if no gas appliances are working, there may be a supply issue. Call Cadent on 0800 111 999.

If None of the Checks Resolve It: Stay Warm and Protect the Pipes

Once you've established this needs an engineer, two priorities: keeping the household warm and protecting the property from frozen pipes.

Supplemental Heat Sources

• Electric panel heaters or oil-filled radiators are the most efficient supplemental heat for sustained use — more economical than fan heaters for overnight use
• Electric fan heaters heat a room quickly but are expensive to run continuously — use to boost a room quickly, not for overnight heating
• Focus heat where people are: one well-heated room is more practical than trying to maintain temperature throughout the house
• Consolidate sleeping arrangements into one or two rooms where supplemental heaters can be safely used overnight

Protecting Pipes Overnight

The risk of frozen pipes rises significantly when the boiler is off during cold weather. Keep the property above 12°C if possible — the temperature below which frost damage to pipework becomes a serious risk. Open airing cupboard and under-sink cupboard doors to allow warm air to reach pipes near external walls. If you're leaving the property empty at any point during the breakdown, leave a fan heater on a thermostat set to 12°C minimum, or drain the system if the outage will be extended. Read our winter preparation guide at preparing your plumbing for winter for more detail on protecting pipes.

What to Tell the Engineer When You Call

The more information you can provide when booking, the more likely the engineer can bring the right parts on the first visit:

• Boiler make and model (shown on the front panel)
• Any fault code displayed
• When it stopped and whether anything changed beforehand
• Whether you have hot water (if hot water works but heating doesn't, see our guide on hot water but no heating)
• Whether you've already tried repressurising or resetting

Landlord Obligations

If this is a rental property, the landlord is legally responsible for restoring heating as quickly as reasonably possible. In cold weather with vulnerable occupants, 24 hours is the widely accepted standard for urgency. Tenants are entitled to report an unresponsive landlord to the local council's housing team if reasonable timeframes are not met.

Our emergency plumbing service prioritises heating failures in cold weather across Peterborough. Call 02039514510 or book online and we'll confirm the earliest available appointment.

Frequently Asked Questions

How do I thaw a frozen condensate pipe?

The condensate pipe is typically the grey or white plastic pipe (20–32mm diameter) exiting through an external wall low on the building, running to an external drain. In freezing weather, slowly pour warm (not boiling) water along the pipe from the wall outwards, working your way to the end. Once the blockage clears, reset the boiler. Fitting lagging around the exposed external section of pipe prevents recurrence.

Is it safe to use a gas oven or hob for heating?

No — never use a gas oven or hob for space heating. They produce carbon monoxide when operating without adequate ventilation and are not designed for sustained unattended operation. The risk of CO poisoning is real and significant. Use only purpose-designed electric heaters for supplemental warmth.

Will my pipes freeze overnight with the boiler off?

At external temperatures just below freezing (0 to -5°C), pipes in heated interior spaces are generally safe overnight. Pipes in unheated spaces — loft, garage, external walls — are at risk when it's significantly below zero for extended periods. Keep interior temperatures above 12°C and open airing cupboard doors to give interior pipes maximum protection.

My boiler is over 15 years old and has broken down. Should I repair or replace?

This is the right question to ask. Our engineers will always give you an honest assessment of repair vs replacement economics on older boilers. As a general guide: if the repair cost exceeds 30–50% of a new boiler's price, or if the boiler has had multiple repairs in the past two years, replacement is usually the more economical long-term choice. Our guide to boiler repair vs replacement walks through the decision framework.