Should You Turn Off Your Hot Water System When You Go on Holiday?

Does Turning Off Your Hot Water System Save You Money?

For a weekend away, there is usually little reason to turn off your hot water system purely to save energy. For a longer holiday, the answer mainly comes down to whether your system stores hot water or heats it as you use it.

A storage hot water system continues maintaining the temperature of the water in its tank while you are away, so switching it off or using a holiday mode can reduce energy use.

A continuous flow hot water system heats water when you open a hot tap. With nobody home using hot water, there is generally little energy to save by switching it off.



You don't need to know the model number to get a reasonable idea of what type of system you have. Start by looking at the unit itself.

Electric Storage Hot Water

An electric storage system has a large tank that stores heated water ready for use. An electric heating element heats the water and switches on again when the temperature in the tank drops.

Gas Storage Hot Water

A gas storage system also has a large tank, but uses a gas burner to heat the water. You should see a gas connection to the unit, and some systems have a pilot light. The burner cycles on as required to maintain the temperature of the stored water.

See what to do if the pilot light went off here...

Gas Continuous Flow Hot Water

Gas continuous flow systems are generally compact rectangular units mounted on an outside wall. They do not have a large storage tank. When you open a hot tap, water passes through the unit and the gas burner heats it.

Electric Continuous Flow Hot Water

Electric continuous flow systems also heat water as it is required rather than keeping a tank of water hot.They can range from small units supplying an individual outlet to larger systems capable of supplying multiple hot water outlets.

So, Does Turning Off Your Storage Hot Water System Save Money?

Yes! If you are going away for an extended period, this is the type of hot water system where switching it off can make a difference. Even when nobody opens a hot tap, the water inside a storage tank gradually loses heat. The system then uses electricity or gas to bring it back to its set temperature. This cycle can continue throughout your holiday despite nobody using the hot water.

For a weekend or a couple of days away, the potential saving is generally small. If you are going away for a week or several weeks, switching the system off or using a holiday setting can reduce this standby energy use.

With an electric storage system, the electric heating element periodically switches on to maintain the tank temperature. Many systems have a dedicated circuit at the switchboard, although you should check the manufacturer's instructions before switching yours off. With a gas storage system, the burner periodically fires as the stored water cools. Some systems have a holiday or vacation setting, while others have specific shutdown procedures. Follow the manufacturer's instructions, particularly where a pilot light or gas controls are involved.

Keep in mind that a storage system will need to heat the tank again when you return. Depending on the system and tank size, you may need to wait before you have a full supply of hot water.



Should You Turn Off a Continuous Flow Hot Water System?

There is generally little reason to turn off a continuous flow hot water system purely to save energy while you're away. These systems don't maintain a tank of hot water. The main heating system operates when hot water is being drawn.

With a gas continuous flow system, the burner fires when you open a hot tap and stops when hot water is no longer being used. With an electric continuous flow system, electric heating elements heat the water as it passes through the unit when hot water is required.

If nobody is home using hot water, neither type is repeatedly heating a tank throughout the day. Some systems may still use a small amount of electricity for controls or other functions, depending on the model.

If you want to completely shut down a continuous flow system while you're away, check the manufacturer's instructions for the correct procedure.



What About Heat Pump and Solar Hot Water Systems?

Heat pump and solar systems need to be considered separately because their operation and controls can vary between models.

Heat Pump Hot Water

Heat pumps generally store heated water in a tank, which means the system can continue operating while you're away to maintain the water temperature. Before cutting the power, check whether your system has a holiday, away or vacation mode. If it does, follow the manufacturer's instructions for using that setting during an extended absence.

Solar Hot Water

A solar hot water system may include solar collectors, a storage tank, circulation equipment and an electric or gas booster. If your aim is to reduce purchased energy while you're away, the booster is an important part of the system to consider. Whether the booster or any other component should be switched off depends on how your particular system is configured. Check the manufacturer's instructions before shutting down a solar hot water system or its components.



Should I Turn Off the Mains Water When I Go on Holiday?

Your mains water supply is a separate consideration when preparing the house for a holiday.

If a pipe, flexible hose, appliance connection or fitting fails while the property is empty, water can continue flowing until the leak is discovered. Turning off the mains water supply can reduce the amount of water released if something fails while you're away.

Before turning it off, check whether anything at the property needs a water supply while you're gone, such as an automatic irrigation system.

If you switch off both the mains water and a storage hot water system, make sure the water supply is restored and the storage tank is full before restarting the hot water system.

How Do I Turn My Hot Water Back On After a Holiday?

Follow the manufacturer's restart procedure for your particular system.

For a storage hot water system, make sure the water supply has been restored and the tank is full before turning the heating system back on. This is particularly important with electric storage systems, as energising the heating element without the tank being properly filled can damage the element.

Allow time for the tank to reach its normal operating temperature before expecting a full supply of hot water.

Gas storage, heat pump and solar systems may have additional restart procedures if they were completely shut down.