Boiler Breakdown at Night: What You Can Safely Do Until Morning

First two minutes: is anything dangerous?

Most boiler breakdowns at night are an inconvenience, not an emergency. Three situations are different, and they come before anything else on this page.

• You smell gas: open doors and windows, then turn off the gas at the meter if you can reach it safely (not if it is down in a cellar). Do not switch lights or appliances on or off. Leave the property and call the National Gas Emergency Service on 0800 111 999. It is free and runs 24 hours
• Someone has a headache, dizziness, nausea or drowsiness that eases outside, or the carbon monoxide alarm has gone off: open windows, turn the boiler off, get everyone outside, call 0800 111 999, then get medical advice
• Water is leaking from the boiler or pipes: turn the boiler off, turn off the water at the stopcock, and keep water away from sockets and the boiler wiring

Never open the boiler casing, however simple the fault looks. Nothing behind it is a householder check.

The safe checks, in the order worth doing them

If nothing is dangerous, work down this list. Each step takes a minute or two, and it is ordered so the most common night-time causes come first.

• Power: is the display lit? Check the fused spur switch next to the boiler, and the consumer unit for a tripped circuit. A trip that repeats straight away is a fault; leave it off
• Pressure: on a combi or system boiler, the gauge should read about 1 to 1.5 bar cold. Many boilers lock out once it falls below roughly 0.5 bar. Top up through the filling loop if you know how
• Reset once: if the display shows a fault code, press reset one time and wait. If it locks out again, stop. Repeated resets do not fix the cause, and boiler manuals say to call an engineer when a lockout comes back
• Controls: check the programmer or smart thermostat is calling for heat, the batteries in a wireless stat are not flat, and the clock has not reset after a power cut
• Frozen condensate pipe: on a cold night, a condensing boiler that gurgles and locks out often has a frozen plastic pipe outside. Pour warm, not boiling, water along it or hold a hot water bottle on it, then reset
• Gas supply: if the hob does not light either, check the prepayment meter has credit and the meter valve is open. If the whole street is affected, the gas network will already know

Keeping warm and getting hot water tonight

If the boiler will not come back, the aim is to get safely through a few hours. Close doors and curtains and gather everyone into one or two rooms. An oil-filled radiator is the safest temporary heat; a fan heater will do, but keep a closer eye on it. Keep heaters clear of bedding and curtains, plug them straight into a wall socket rather than an extension lead, and switch them off before you go to sleep.

Never use a gas cooker, oven or hob to heat a room, and never bring a camping stove, patio heater or barbecue indoors. They all produce carbon monoxide in a closed room.

For hot water, if you have a hot water cylinder in an airing cupboard, look for an immersion heater switch nearby. Switching it on heats the cylinder by electricity, which usually takes an hour or two depending on the cylinder. A combi boiler has no cylinder, so the kettle is the only option until it is fixed. If only the hot water has gone and the radiators still heat, see boiler heating radiators but not water.

Protecting the house on a freezing night

A house with no heating in a hard frost can freeze its own pipes, especially in lofts, under suspended floors and on outside walls, the same spots a winter plumbing checklist has you lag before the first frost. Leave the loft hatch open for an hour to let some warmth up, open the kitchen cupboard doors under the sink, and, if heat must stay on overnight, run an oil-filled radiator on low in the coldest room with pipes, a metre clear of anything that can burn.

If a pipe does freeze, do not attack it with a blowtorch or heat gun. Turn the water off at the stopcock and thaw it slowly with a hairdryer on low or warm towels, working from the tap end back. Frozen pipes: what to do covers what to watch for, because a split usually only shows once it thaws.

Can it wait for morning, or is it worth a night call-out?

That is your call, and it depends on who is in the house and how cold it is. Most breakdowns with no leak and no gas smell can wait a few hours in a house that holds its heat. It is worth calling tonight when any of these apply:

• A baby, an elderly relative or someone unwell is at home and the house is getting cold
• The outside temperature is well below freezing and pipes are at risk
• Water is leaking and you cannot stop it at the stopcock
• The pressure relief pipe outside is pouring water, or the boiler is making a loud banging noise

What happens when you call an engineer out

Tell whoever you call the boiler make and model from the front panel, any fault code on the display, what the pressure gauge reads and what you have already tried. That lets the engineer bring the likely parts, which is the difference between a fix tonight and a second visit.

On site the engineer checks the gas supply and burner pressure, reads the fault history, and tests the part the code points to: often the ignition electrode, the fan, the pump, a pressure sensor or the diverter valve. No engineer carries every part for every boiler, and a make-safe tonight with the part fitted the next day is sometimes the honest answer. Gas work is carried out by Gas Safe registered engineers.

For an emergency boiler repair the £60 call-out is the same at any hour, and the repair price is agreed with you on site before any work starts. If you want to work through more causes before calling, the boiler not working checklist goes further than the night-time list above.