What to Do If Your Boiler Breaks Down in Winter

Start With the Simple Checks

A boiler that will not fire on a cold morning is miserable, but it is not always a serious fault. Before you ring anyone, work through the basics — you may fix it yourself in five minutes.

• Check the thermostat and programmer. Has someone knocked the room thermostat down, or has the timer switched to "off"? In winter, set the thermostat to around 20°C and make sure the heating is actually switched on at the control panel.
• Look at the power supply. Is the boiler plugged in or switched on at the fused spur? Check your consumer unit for a tripped circuit breaker.
• Read the display. Many boilers show a fault code or a flashing light. Note the code down — an engineer will ask for it, and it often points straight to the problem.
• Try the reset button. Press it once, wait a few minutes, and see whether the boiler fires. If it locks out repeatedly, stop pressing and call for help.
• Check the gas supply. If your hob will not light either, there may be a supply issue. If you smell gas, open windows, do not touch electrical switches, leave the property and call the national gas emergency number straight away.

Check the Pressure Gauge and Bleed Your Radiators

Low system pressure is one of the most common reasons a boiler stops working, and it is usually easy to correct.

Find the pressure gauge, either on the boiler itself or on a separate filling loop. When the system is cold, the needle should sit between 1 and 1.5 bar. If it has dropped below 1 bar, the boiler may refuse to fire.

To top it up, open the valves on the filling loop slowly until the gauge reaches around 1.2 bar, then close them tightly. Do not overfill — pressure above 2.5 bar can trigger the pressure relief valve and cause a leak.

While you are at it, bleed your radiators. Trapped air stops heat circulating and can push pressure up and down. Starting with the radiators upstairs, hold a cloth under the bleed valve, turn the radiator key until you hear a hiss, and close it as soon as water trickles out. Check the gauge afterwards and top up if needed.

If the pressure keeps falling within days, you likely have a leak or a faulty component. That is a job for a qualified engineer, not a DIY fix.

The Frozen Condensate Pipe — A Classic Winter Culprit

Modern condensing boilers produce water that drains away through a white plastic pipe, usually running outside to a drain. In a hard frost, that pipe can freeze solid, and the boiler shuts down to protect itself. It is one of the most common causes of a winter breakdown.

Look for the pipe outside, often near a downpipe or gully. If it is frozen, you can often thaw it by pouring warm — never boiling — water along its length, or by wrapping a hot water bottle or warm towel around it. Once cleared, reset the boiler.

Do not use a naked flame or pour boiling water on it, and never chip at ice with a screwdriver or similar tool. If the pipe is high up, hard to reach, or keeps freezing, ask an engineer to fit a wider pipe, a condensate trap, or insulation.

Renting? Know Your Landlord's Duties

If you rent, the repair is your landlord's responsibility, not yours. Under the Landlord and Tenant Act 1985, landlords must keep heating and hot water installations in proper working order. The Homes (Fitness for Human Habitation) Act 2018 reinforces this — a home without adequate heating can be classed as unfit to live in.

Report the fault to your landlord or letting agent in writing, by email or text, and keep a copy. Ask for a timescale. In winter, a total loss of heating and hot water should be treated as urgent, and a Gas Safe registered engineer should attend quickly — often the same day or within 24 hours.

• Do not withhold your rent. It weakens your position and can lead to eviction proceedings.
• If your landlord ignores you, contact your council's environmental health or private rented sector team. They can serve an improvement notice and, in serious cases, do the work themselves.
• If the boiler is beyond repair, ask what temporary heating or alternative accommodation your landlord will provide.

Never attempt gas work yourself, and never let an unregistered trader touch the boiler. Ask to see the engineer's Gas Safe ID card.

Staying Safe and Warm While You Wait

Keep warm with layers, blankets, hot water bottles and hot drinks, and stay in one room where possible rather than heating the whole house. If you are elderly, disabled, or have young children, cold homes can be genuinely dangerous, so do not feel you are making a fuss by asking for urgent help.

Check you have a working carbon monoxide alarm. Warning signs include a yellow rather than blue flame, black sooty marks, and headaches or dizziness. If you suspect carbon monoxide, get fresh air, leave, and call for help.

If a repair is unaffordable, help may be available. Your local council can advise on the Household Support Fund, and you may qualify for the Cold Weather Payment or Warm Home Discount. Energy suppliers also keep a Priority Services Register for vulnerable households — ask to be added.

Finally, if you cannot stay in your home or your tenancy is at risk, contact your council's housing options team. Under homelessness legislation, they must assess your situation and, where you are in priority need, provide help. A housing advice charity can support you through that conversation. Nobody should face a freezing night alone — reach out early, and keep asking until you are warm and safe.