Is it Cheaper to Leave Hot Water On All The Time?

There’s a myth makes some people believe that it is cheaper to leave the hot water on all the time.

Is that true? Or does it actually cost more money to keep the boiler or the water heater on continuously?

And in case that you have to turn it off in order to save money, then what solutions are there in order to get hot water on demand when you need it without having to wait for the water to heat up?

I’m an electrical engineer and an energy manager with 10+ years of experience, and I wrote this article in order to help you know the necessary answers to all of these questions, and to give you solutions that can save you money on the long run, and keep it comfortable for you.

Let’s dive in!

Is it Cheaper to Leave Hot Water On All The Time?

No, it is not cheaper to leave the hot water on all the time, because there will be some times that you won’t need to use hot water for several hours, or maybe you will still use it, but you don’t need it to be at a very high temperature.

Normally, depending on the insulation of the water heating system components such as: tank, cylinder, boiler, pipes, …etc., the water temperature will tend to keep going down because no insulation is 100% efficient.

And keeping the hot water system on all the time will try to keep the water temperature at the highest possible degree, which means consuming more energy continuously.

And if you don’t need to use the hot water during the day because you are at work, then keeping the water heating on all these hours can lead to wasting electricity on unnecessary heating in order to maintain the high temperature all the day.

And even at night for example, you might need to use some hot water if you wake up at a later hour to go to the bathroom, but you need only a little amount of hot water.

And if you turn off the hot water before you go to bed, then the water will maintain a comfortable temperature during the night, even if it didn’t keep it at the highest possible degree.

That’s why, it might not be necessary to keep the water heating on all the time at night.

Why Do Others Say That it Is Cheaper to Keep Hot Water On All The Time?

Some say that it is cheaper to just keep the hot water on continuously assuming that doing so will prevent the temperature from going down a lot and heating again from there, and that it is cheaper to just keep it on all the time.

But this is a false assumption, as leaving the water heating on continuously will accumulate energy consumption that exceeds what you need when heating the water all the way up if you turn the water heating on when you needed it.

Pete from House Hold Money Saving proved that through an experiment where he compared between the energy consumption in two consecutive and similar months.

And he kept the water heating on continuously in the first month, and turned it on only when needed in the second month, and found out that it actually costs more when you keep the water heating on all the time.

Does That Apply to All Water Heating Systems of All Kinds?

For most water heating systems, it costs more when you keep the water heater on continuously.

This applies to electric water heaters that has tanks in them, and to boiler based water heater with cylinders or tanks.

However, for a combi boiler, since it only heats water when you start using it through opening a tap (on demand), then you don’t need to switch it off as it switches on and off automatically.

The same applies to tankless water heaters as they work only when a hot water tap is open, which means that you don’t waste energy on unnecessary heating of water.

Hot Water On Demand with Tankless Heaters

Here are some of the frequently asked questions about leaving the water heating on all the time and its effect on your bills:

Should I Turn My Water Heater Off at Night?

Yes, it is better to turn the water heater off at night since you won’t need to use a significant amount of hot water, and most systems will keep the water at a comfortably hot or warm temperature for a couple of hours when you don’t consume a lot of hot water.

Do You Save Electricity by Switching Off The Geyser?

Yes, you do save electricity by switching off the geyser (water heater with tank) as leaving it on will make it keep going on and off based on how fast the water temperature drops down to a certain level.

And leaving the geyser on all the time means that you will waste electricity during the time the water is heated when you don’t really need to use it hot.

This especially important in cold weather as leaving the geyser on all the time can cause your electric bill to be so high in winter.

Is it Cheaper to Leave Immersion Heater On All The Time?

No, it is better to turn on the immersion water heater only when you need hot water. Leaving the immersion heater on all the time will cost more money.

Can I Leave My Boiler On Continuously?

It depends on why do you use the boiler.

When used only to provide hot water, then it is better NOT to leave the boiler on continuously.

But if you use it for space heating through radiators or underfloor, then you might need to leave the boiler on all the time in order to keep the place warm.

However, you can use a smart thermostat in order to regulate the operation of the heating system so that it doesn’t run the boiler and the heating system at full load all the time.

Do You Save Money By Turning Off a combi Boiler or a Tankless Water Heater?

Not necessarily, as these types of heaters consume energy on heating water only when you demand hot water through opening a hot water tap for example.

Does Turning Off The Water Heater Save Money?

Turning off the water heaters saves money if they on heating water and keeping it hot inside a tank, but not necessarily if you use a combi boiler or a tankless water heater.

How Much Do You Save by Turning Off The Water Heater?

The energy and money savings you make from turning off the water heaters are different based on many factors, such as:

  • The fuel used to heat water. (e.g. electricity, gas, …etc.)
  • The size of the tank of the water heater.
  • The efficiency of the water heater. (Depends on the technology, manufacturer, heater age, …etc.)
  • The insulation of the hot water tank.
  • How often and how much you need to use hot water.
  • The prices of the gas or electricity in your area.
  • How cold is the area you live in.

It is completely different from one case to another to know how much energy and money you can save by turning on and off the water heating system based on your needs.

But what is to be assured is that heating water consumes a lot of energy, and turning the water heaters on only when necessary will definitely save you a lot of money on the short and long run.

Another Tip for Lowering Your Water Heater’s Energy Consumption

As our friend Arlin mentioned in the comments below, you can lower the energy consumption of your water heater by re-adjusting the thermostat that is responsible for the internal on-off operations and lowering the set temperature to the one that you would still get a comfortable degree of hot water, which would lead to shorter overall on-duty time, and thus, less energy usage to power the water heater.

4 Ways for Hot Water On Demand without Keeping The Heater On All The Time

It might not feel convenient for some people to keep turning on and off the water heater every day, and they would just keep it on continuously all the days, which costs a lot of money that could be saved.

If this is you, here are some solutions that can save you a lot of money with a little investment:

Combi Boilers

Combi boilers are boilers that are designed to provide hot water on demand for both, heating systems and for hot water usage.

But the nice thing is that these combi boilers work only on demand, meaning that when you open a hot water tap, or when the water of the heating system goes under a certain temperature.

Therefore, you can get hot water on demand without keeping heating the water continuously and wasting energy.

These boilers only heat water as you need it, which means that you don’t waste money on unnecessary heating of water.

Also, since combi boilers don’t come with tanks, they can fit in smaller spaces, and that makes them ideal for apartments or small houses.

Tankless Water Heaters

Tankless water heaters are another option to get hot water on demand without heating a lot of water continuously.

These heaters can work on gas or electricity, and they only turn the heating on when you open a hot water tap.

These cost more than the normal water heaters with tanks or cylinders, but they save more on the long run.

Water Heater Timers

Ok, maybe you already have a water heater installed, and you don’t have the money to invest in a tankless water heater, or maybe you need hot water in big quantities from different points at the same time.

In this case, in order to get hot water from normal water heaters with tanks, and still save on energy, you can use countdown or programmable water heater timers that can turn on and off based on previous settings or schedules.

Use Water Heater Timer to Save Money

For example, you can schedule the water heater to switch on one hour before you wake up, or before you come back from outside, so that you find hot water once you are up and home, while saving money by not keeping the water heating on all the day and night.

Smart Thermostats

Smart thermostats are also good for regulating the water heating operation in order to save energy and money, which makes them one of the most important devices to save electricity at home.

These thermostats can be connected to the boiler in order to regulate its operation based on a schedule that you put, which depends on the hours you need it to work in order to heat the space and to provide hot water.

Also, you can schedule them to work based on the space temperature in order to maintain a certain degree.

And because these smart thermostats can be connected to your WIFI network, you can control them remotely from your smart phone even if you are not at home.

These solutions can help you save money by not keeping the water heating system on all the time, and each one can be the best solution for you in certain cases based on where you live, how much hot water you need, how big your house or apartment is, how cold is the area you live in, the current water heating system you have, …etc.

In order to find out the best solution, you may consider contacting a professional to consult them, and maybe they can give you a quotation on doing the necessary changes to your water heating system.

Conclusion – Don’t Leave The Water Heating On

In general, leaving the hot water on all the time is not cheaper.

Unless you are using a tankless water heater or a combi boiler, it is better to turn the water heater off when you don’t need hot water for several hours in row, as it will cost you more to leave it on.

Consider using any of the four solutions I mentioned in the previous section above in case that you want a convenient way to get hot water on demand while saving money and energy at the same time by not having the water heating continuously.

If you still have a question on anything I mentioned above, or if you need help in anything related to this topic, leave a comment below and I will do my best to answer you asap 🙂

And if you know someone who could benefit from reading this article, please, feel free to share it with them.

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