Away for Christmas? How to Leave Your Glow-worm in a Safe Holding Pattern

There's a particular kind of quiet that settles over a house when the suitcases are by the door and the last person has checked the back door twice. If you're heading away for Christmas 2026, that quiet will last a week or two — and your Glow-worm combi will be the only thing in the building still doing a job. The temptation is to switch everything off at the wall, lock up and feel virtuous about the saving. Resist it. An empty house in a British January is exactly the scenario frost protection was invented for, and a boiler left in a sensible holding pattern is cheaper than a burst pipe and a collapsed ceiling.

Here's how to leave yours in safe hands.

Switching off is not the same as saving

A modern Glow-worm combi has frost protection built in, but that protection needs electricity and gas to work. Turn the boiler off at the fused spur and you haven't saved anything — you've removed the one appliance that could keep the pipework above freezing. The few pounds of gas used by a boiler idling at a low temperature are trivial next to the cost of tracing a leak, replacing sodden plasterboard and arguing with an insurer about whether the house was "left unattended" in breach of your policy. Check your policy wording before you go, too; many UK insurers expect heating to be left on or the water to be drained if a property is empty for more than a set number of days.

A fifteen-minute walk-round before you go

You don't need a toolkit. You need to be methodical.

• Thermostat down, not off. Set room thermostats to around 12–15°C. That's warm enough to keep the fabric of the house and the pipework safe without heating the street.
• Leave the boiler powered. Don't touch the fused spur. If your installer fitted an external frost thermostat, check it hasn't been switched to "off" by mistake.
• Check the pressure. A cold combi should read roughly 1–1.5 bar on the gauge. Top it up now rather than discovering a low-pressure lockout on your return.
• Clear the flue and airbricks. Remove anything stacked against the terminal, and make sure vents aren't blocked by bins, planters or Christmas delivery boxes.
• Lag the condensate pipe. If any part of the white plastic condensate run is outside or in an unheated garage, add foam lagging before you leave. This is the single most common winter call-out.
• Close windows, leave internal doors open. A little air movement helps, and open internal doors let residual heat circulate.

Holiday mode on your controls

If you have Glow-worm's smart controls, or a compatible third-party thermostat, use the holiday or away function rather than simply switching the schedule off. It holds a lower setpoint and then resumes normal operation on the day you return, so you're not walking into a cold house or a boiler that's forgotten its routine. Turn off geofencing while you're away — otherwise the system may decide nobody is home and drop to a level you didn't intend. If your controls offer a minimum-temperature setting, set it and leave it alone. And resist the urge to tinker remotely every day; a stable setpoint is more efficient than a thermostat that's being adjusted from a beach bar.

The condensate line deserves a second look

A condensing Glow-worm produces water all winter, and that water has to leave the building. In a cold snap, an unprotected external run can freeze solid, the boiler locks out and you come home to a cold house and a fault code. Lagging is cheap insurance. If the pipe runs to an outside drain, check the drain isn't blocked with leaves, and make sure the pipe falls continuously rather than sitting in a dip where water can pool. If you've had a freeze-up before, ask your installer about rerouting the condensate internally — it's a small job that pays for itself the first time the temperature drops below minus five.

Water: isolate the supply, don't drain the system

Turn off the main stopcock before you leave and open the cold taps briefly to release the pressure in the pipework, then close them again. That limits the damage if a pipe does split. Don't drain the central heating system — that's a job for a professional and it removes the water that's doing the frost-protection job. Leave the boiler's own water where it is, keep the heating on its low setting and let the system look after itself.

Give someone a key and a phone number

Ask a neighbour or a family member to pop in every few days. They don't need to do anything technical: check the boiler is still running, look for water where water shouldn't be, and listen for alarms. Leave your installer's number on the kitchen table and a note of the boiler model. If the worst happens, a quick call is far better than a discovery three weeks later.

What to check when you get back

Before you do anything else, have a sniff near the boiler — if you smell gas, don't touch switches, open the windows and call the gas emergency line. If the house is cold, check the pressure gauge and the boiler display first. A low-pressure fault is usually a simple top-up, not a new boiler. Then run the hot taps, check a couple of radiators for heat and listen for any new noises. If something doesn't feel right, book a service rather than prodding at it yourself.

The bottom line

An empty house doesn't need an empty boiler. It needs a low, steady holding pattern: power on, thermostat down, water isolated, condensate lagged and someone keeping an eye on it. Do that before you lock the door and you can enjoy Christmas lunch without wondering whether the pipes are coping.