Should I Turn My Water Heater Off At Night?


If you've been debating whether you should turn your water heater off at night then you may have noticed that there are plenty of different opinions about this subject. Some voices online are firmly against it while others can't recommend it enough.

We've put together this guide to give you all the information you need to make an informed decision. We'll cover how water heaters work, the pros and cons of turning them off at night, and much more.

What is a water heater?

A hot water heater does exactly what it says on the tin - heats water. Boilers serve a similar function, which is why it's common for people to think of the two appliances as the same thing. However, they are different.

Water heaters warm potable water that's safe for cleaning and cooking. Boilers also do this but they heat water that's used in a central heating system as well.

So, if you have a water heater in your home, you will also need a separate appliance to keep your home warm. Of course, many homes in the UK have boilers, such as a combi boiler, to perform both functions.

For the purposes of this article, we will be focusing on water heaters rather than boilers.

How does a water heater work?

Water heaters can be divided into two categories - tankless and tanked heaters.

Tanked water heaters warm incoming cold water using a gas burner or electric heating rods that are inside the tank. When the water is at the correct temperature it's then stored in a hot water tank or hot water cylinder. This means that you have hot water waiting for you when you turn on your shower or tap.

The temperature of the water that comes out of your tap or shower depends on how much you turn the handle. If you turn it all the way, then the water heater will send hot water directly to the tap mixed with a small amount of cold water.

If you only turn it slightly then the hot water will be mixed with more cold water resulting in a lower water temperature.

A tankless water heater works in a very different way. Instead of storing water in a hot water tank, it instantly heats water when you turn on your shower or tap. It continues to heat the water for as long as you leave the tap or shower turned on.

As mentioned, many homes use boilers for hot water and central heating in the UK. This can eliminate the need for a hot water heater.

Should you turn your water heater off at night?

There has long been a debate about whether it's best to leave your water heater on all the time or turn it off when it's not in use. Some argue that turning it off at night helps you save money and is better for the environment.

However, others argue that the money you save isn't worth it when compared to the issues that turning it off regularly can cause.

At PlumbNation, we've come to the conclusion that it can be worth turning your water heater off at night. Still, the pros and cons are slightly different depending on whether you have a gas water heater or an electric water heater.

Let's take a look at the upsides and downsides of turning your water heater off at night to help you make the right decision.

Pros of turning your water heater off at night

It can help you to save money


Whenever your water heater is on, some heat will be escaping from it. If the unit is well insulated then it will only be a small amount of heat. For poorly insulated units, the heat loss can be fairly significant.

Of course, losing heat in this way leads to more energy consumption and increased heating bills. Some estimates state that turning your water heater off at night could save you up to 10% on your monthly energy bills.

If you have an electric water heater, and you're on an Economy 7 tariff, then it's usually more cost-effective for it to turn on for at least a couple of hours during the night. This is the cheapest time for you to consume energy and you need to take advantage of it.

It's more eco-friendly


Turning your water heater off at night helps to save energy that would otherwise be wasted. Reducing the amount of energy your home uses is good for the environment and will lessen the carbon footprint of your home.

Increases longevity

Having a hot water supply for your home is very important and you want your water heater to last for as long as possible. By turning it off at night, the amount of wear and tear the unit experiences can be reduced. In turn, this can lead to better longevity and an increased lifespan.

Cons of turning your water heater off at night

A lack of hot water in the morning

One of the main downsides of turning your hot water heater off at night is that you'll have to wait for a while before you can have a hot shower in the morning. This is only an issue if you have a tanked water heater.

Depending on how efficient your unit is, you may have to wait between 20 minutes to an hour before the water temperature is high enough for a hot shower.

Difficulties turning back on

Newer water heaters should have no problem turning back on again in the morning when they've been left turned off at night. However, if you have a relatively old heater then you may encounter issues when turning it back on.

Older units may experience a high amount of stress when attempting to produce hot water after being left off for several hours. This could lead to your heater needing costly repairs.

A buildup of hard water


If you live in an area with hard water, then turning your heater off at night could have negative consequences. When the heater is turned off, minerals from hard water start to accumulate inside it. This can cause damage to the unit and could make it less energy-efficient.

When else might you want to turn your water heater off?

Besides turning your water heater off at night, there are other times when you may also consider turning it off. Many people choose to do this when they're going on holiday or are planning to be away from home for a long time.

Yet, turning your heater off for an extended period is a lot different to turning it off for several hours at night. It carries some risks and could have a significantly negative effect on the unit.

For example, if you're going away during the winter then it can be especially risky to leave your water heater turned off while you're away. This is because your heater maintains the tank's temperature. If it's turned off during low temperatures, then the pipes may freeze and even burst.

Instead of turning it off completely, you should set your water heater to a lower temperature than usual while you're away from home. This will save energy and eliminate the risks of damage to your unit. It will also prevent the possibility of the unit being overloaded when you turn it back on again.

How to turn your water heater off

Whether you have an electric or a gas water heater, turning it off is straightforward.

To turn off an electric heater, you need to find the breaker that's connected to the unit. When you find it, flip the breaker and this will turn off your water heater. Just bear in mind that if any other appliances are attached to the breaker they'll also be turned off.

Your gas heater will have a panel on it with a dial and a number of settings. To turn it off, turn the dial to either 'pilot' or 'off'. If you turn it to 'off' you'll need to relight the pilot light when you turn it back on again.

How to turn your water heater back on safely

Before you turn your unit back on, you need to make sure that the heating element is submerged in water. If it isn't, then it could be irreversibly damaged. This means that you need to ensure the tank is full. Of course, this doesn't apply to tankless heaters.

To check if the tank is full, you need to turn on a hot water tap somewhere in your home. If there's a steady stream of hot water then it means the tank is full. If the hot water tap is hissing and spluttering then it means there's not enough water in the tank.

To allow the hot water tank to fill up you need to ensure that the water inlet valve is open.

Once the tank is full, follow these steps to turn on an electric heater:

  • Go to your electrical panel and flip the breaker that's attached to your heater back on.
  • Wait for your heater to start producing hot water again. This may take a long time depending on the efficiency of your unit.

To turn a gas heater back on, follow these steps:

  • Turn the gas valve off
  • Find the pilot light
  • Find the burner
  • Light the pilot
  • Hold down the gas button in pilot mode
  • Turn the gas on

Is turning your water heater off at night really worth it?

Overall, the main benefits of turning your water heater off at night are that you'll save some money on your energy bills and reduce the carbon footprint of your home. However, the amount of money and energy that's saved isn't huge. There are also downsides to turning it off, such as not having quick access to hot water in the morning.

In the end, your decision should largely be based on the age and condition of your heater. If you have an old unit, then it might not be worth risking turning it off and on again regularly. If you have a newer unit, then it should be able to handle this without any issues.

Water heaters from PlumbNation

If you’re in the market for a new water heater, PlumbNation stock a range of units, from unvented water heaters, venter water heaters, instantaneous water heaters, water heater accesories and more. Should you have any questions regarding your current water heater, a new boiler, or new bathroom or kitchen parts, then our team of experts would be happy to help.


Is a tankless water heater more efficient than one with a tank?

Yes, tankless heaters are generally more efficient than heaters with tanks. A tankless heater produces the exact amount of hot water you need when you turn on a tap or a shower. This means that less energy is wasted. Heaters that use a hot water tank or hot water cylinder tend to waste more energy.

How long should my water heater last?

Your heater unit should last for around 20 years if it's tankless. If your heater does have a tank, it should last for between 10 to 15 years.

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