Should You Turn Your Boiler Off Before Going on Holiday?

It's generally recommended to adjust your boiler settings before going on holiday, but whether you turn it completely off depends on several factors, including the type of boiler, the time of year, and the length of your trip.

Here at City Plumbing, our plumbing and heating experts offer help and advice on dealing with your boiler over the holiday season for increased peace of mind.

What Are The Differences Between Boiler Types?

Firstly, whether you should leave your boiler on or off when you go on holiday largely comes down to the type of boiler you own. The most common types of boiler include combi boilers, system boilers, gas boilers, LPG boilers, and oil boilers, with each one having different requirements.

Combi Boilers (Combination Boilers): These provide instant hot water and heating on demand.

Turning off: Often less critical to keep on for frost protection compared to systems with water tanks, as they don't have a large volume of water to freeze. However, running the pump periodically can prevent it from seizing.
Recommendation: For short trips (a few days), setting it to a very low temperature (e.g. 10-12°C) or using a "holiday mode" if available is often sufficient. For longer trips, you might turn it off, but consider our "winter" advice below.

System and Regular (Conventional) Boilers (with hot water cylinders): These heat water that is then stored in a hot water cylinder, and also provide central heating.

Turning off: If you turn these off completely, the stored hot water will cool down, and the heating won't come on at all.
Recommendation: For frost protection, it's generally better to leave them on with the thermostat set to a low temperature (e.g. 10-12°C) or use a "holiday mode." This ensures the pipes don't freeze.

Gas Boilers (Natural Gas): Most common type in many areas.

Considerations: Generally reliable. Risk of freezing pipes is the main concern when switched off.
Recommendation: Follow the advice for combi, system, or regular boilers as appropriate.

LPG Boilers (Liquefied Petroleum Gas): Similar to natural gas boilers in operation but use LPG stored in a tank.

Considerations: Fuel supply needs monitoring. Same frost risks as natural gas.
Recommendation: Similar to natural gas boilers, consider leaving on low for frost protection, especially if the tank might run low while you're away.

Oil Boilers: Use heating oil stored in an external tank.

Considerations: Fuel level needs checking before you go. Can be more susceptible to issues if left completely off for long periods in very cold weather, but less so than water-based systems.
Recommendation: As with other boiler types, a low temperature setting for frost protection is often advisable, particularly in winter.

Summer vs. Winter Holidays

Is It Cheaper to Switch my Heating Off on Holiday?

In summer, if there's no risk of frost, you can generally turn your boiler off completely, especially for longer trips. This is recommended if you won't need heating, and if you have a combi boiler, and you won't need hot water until you return. For system/regular boilers, the stored hot water will cool, but you can just heat it up when you get back. Yet, the exceptions here are if you have any concerns about damp or want to ensure minimal air circulation. Leaving it on a very low setting might be considered, though this is less common.

Should I Leave My Boiler on During My Winter Holiday?

For winter holidays, or periods with frost risk, it’s highly recommended that you leave your boiler on with the thermostat set to a low temperature (e.g. 10-12°C or a "frost protection" setting). This prevents pipes from freezing and bursting, which can cause significant damage. Even if you only have a combi boiler, pipes running to outside taps or in unheated areas could still freeze.

You could instead consider "Holiday Mode". Many modern boilers and thermostats have a "holiday mode" which maintains a low temperature to prevent freezing while minimising energy consumption.

Keeping Your Boiler on or off When Leaving for Holiday - Important Advice

Water Mode vs. Heating Mode: You can often switch your boiler to "water only" mode if you have a system or regular boiler, meaning it will only heat the hot water cylinder. However, this won't provide frost protection for your heating pipes. For holidays, focusing on overall frost protection (low heating setting) is usually more important.
Holiday Mode: As mentioned, if your boiler or thermostat has a specific "holiday mode," use it. This feature is designed to maintain a minimum temperature to prevent freezing while you're away and will automatically return to your normal schedule when the holiday period ends.
Servicing: Ensure your boiler has been serviced recently and is in good working order before you leave for an extended period. A faulty boiler is more likely to cause issues or fail while you're away.
Pipe Insulation: If you have pipes in unheated areas (e.g. loft, garage, outside) ensure they’re well insulated to reduce the risk of freezing.

Consider Using a Smart Thermostat with Your Boiler

A brilliant feature of smart thermostats is the ability to set your boiler to come on a few days before you return home from your holiday. Most smart thermostat apps allow you to schedule a "return date" or create a temporary schedule that kicks in before you arrive, returning to your normal schedule afterwards.

So, you can turn your boiler off or set it to a very low "holiday mode" temperature while you're away. Then, you can program your smart thermostat to begin warming your home a day or two before your return. This means you come back to a warm house and readily available hot water, without having wasted energy heating an empty property for your entire trip.