Immersion Heater Timer- Ultimate Guide

immersion heater timer

Do you have an immersion heater in your home? If so, then this article is for you! You can save money on electricity by using an immersion heater timer to make sure the immersion heater is off when not in use. This article will provide some tips and tricks for how to set up the timer and get it running without any issues.

This article is meant as an introduction to immersion heater timers for those who may be considering installing one of these devices at their home – it will give you some general information about immersion heaters and what to look out for when buying one online.

An immersion heater timer is a device that automatically turns on and off your immersion heater. It allows you to control the temperature of your home by changing how long it heats up during certain times of the day. You can program different schedules for weekdays, weekends, vacations or holidays; so no matter what’s going on in life – you’re always comfortable!

But which one should you buy? This ultimate guide will help you find out.

Immersion Heater Timer

What is a timer and how does it work?

Immersion heater timers are used to program immersion heaters. When you have installed an immersion heater at your home, the timer is what will help you control the amount of time and water temperature that it’s going to be running.

Immersion heaters are great, but if they’re left on too long or not controlled properly, they can lead to a few problems such as scalding and wasting energy. To avoid these things from happening, an immersion heater timer is a perfect solution for controlling when your immersion heater is on and off each day.

The timer helps prevent these issues from happening by giving you some control over how much time your appliance runs in a cycle (24 hours). Since this device has an LCD screen with programming functions, it also allows you to program everything easily and accurately.

The timer will also have a programmable clock that makes it easy to set up the time (and date) for your immersion heater to turn on and off.

An immersion heater timer is an essential device for anyone that owns an immersion heater that cannot be monitored by a thermostat or any other type of external control system. This little device can help save money in energy costs over time while giving you more control than you would otherwise have over your immersion heater.

It’s important, however, that when using one of these timers, you make sure it fits correctly with the model of appliance and that you familiarize yourself with how to use it properly prior to installation.

Immersion heaters are great devices to save money on your energy bills because they can use the existing hot water from your home to heat up cold or lukewarm water, but if you’re not careful these devices can do a significant amount of damage and cost you big money in repairs.

The first thing we should discuss is immersion heater controls. On most natural gas models there will only be a timer and on electric units, the controls are usually limited to just a few buttons, though sometimes they’ll have sensors that allow them to be controlled by other systems like switches so that they can control the energy usage and provide heating for a larger area.

When it comes to timers immersion heaters can be set anywhere from 1 minute to 99 minutes and there is also the option of having no timer at all – leaving it to work on an on/off cycle that’s controlled by an internal thermostat. Some models may also have the ability to control how hot the water gets (though this can be difficult in a lot of cases) but again this will depend on what type you buy.

One thing you should understand is that your immersion heater always needs time to get up to working temperature, even if it has been previously turned off – one way around this though would be with some special models which use sensors built into them so they can start automatically on their own.

Now, what you need to know is that timers can be an ideal way of controlling the amount of time your immersion heater runs each day – however for this to work effectively you will still need to understand how they actually operate. The most basic timer will switch the immersion heater on and off at pre-set times throughout the day – however, these are often simply switched back on again after a certain period of time (typically 3 or 4 hours) if this means it can end up costing you more than it should.

One option would be with programmable digital timers, which allow you to set them up so that your immersion heater switches on at specific times throughout the day – say between 9 am and 6 pm every weekday.

immersion heater timer

Types of immersion heater timers

If you live in a hard water area and can’t use an immersion heater timer, or if you have a really complex setup with multiple power points, consider getting professional advice on different solutions for heating your water. Some options you may want to consider include underfloor heaters or other forms of electric hot water systems.    

An immersion heater is simply a device that converts electricity into energy needed to boil the water in your hot water tank through electromagnetic induction.

The main types of immersion heater timers on the market are mechanical (with a lever), push-button, or digital.

Mechanical immersion heater timers

They work in a similar way to the old fashioned clockwork egg timer you may have had as a child. They rely entirely on the action of gravity and wheels turning inside the mechanism, rather than any kind of electronic technology – so they’re often cheaper than other options. Mechanical immersion heaters can also be used with both mains and tank-type heating systems.

Push-button models use an electrical switch to trigger water flow through your immersion tank for pre-set periods of time – anything between 30 minutes up to 12 hours is possible depending on how much hot water you need.

Set-and-forget timer

This is a basic immersion heater timer, which simply switches on and off at pre-set times throughout the day – it’s ideal if your usage of hot water remains pretty consistent throughout the year.

Programmable timer

Using this type of immersion heater timer, you can set your immersion to switch on and off at specific times throughout the day. For example, if you work full time from 9 am until 5 pm but have no domestic commitments in the evening after work, you could program your immersion heater to switch on between 1 pm and 6 pm every weekday, meaning you get hot water when it’s most convenient for you.

How to install a timer

To install an immersion heater timer, first, make sure that your immersion heater is switched off at the mains. Then, if there’s a dial on the timer with two positions – one marked ‘on’ and another marked ‘off’ – you’ll need to unscrew it slightly so you can move it between the two.

Next, fit the timer onto your immersion. Usually, a timer has screw terminals or pins for this, but sometimes there are holes instead. Either way, you’ll need to put wires through them, and then attach these wires to the live (usually green) and load (normally red or black) terminals on your immersion heater.

Then secure the screws back in place.

If your timer doesn’t have any screw terminals but does have two metal points, you can easily install them too. Just drill a small hole in the top of your immersion heater and then push the two points through.

Once you have attached it all up, you can turn on your immersion by pushing the timer from ‘off’ to ‘on’ until you hear. Once you are ready to go into standby mode again, just push it back to ‘off. Some words of advice:

Make sure that any wires leading from your timer come nowhere near hot parts within the bath or hot water tank – if they do get too close, just reposition them so they’re well clear.

The plug must be installed somewhere reachable so that when you need to go into standby mode, you don’t have to leave the bath or heating system unattended for a longer period of time to avoid the risk of scolding!

You can also benefit from using an immersion heater timer with other appliances that you use to heat water – for example, if you have a hot tub or swimming pool. The timer will turn off the circulation pump/blower or filtration system automatically when your hot water has reached the required temperature – ensuring it stays at this temperature without wasting any energy.

Benefits of an immersion heater timer

There are a lot of benefits of using an immersion heater timer. Below I will discuss only the main ones.

Immersion heaters are perfect for warming larger quantities of water – so they’re ideal for families and businesses, yet they can be expensive to run if you leave them on all day long (and some people do). That’s where a timer comes in handy. Using one with your immersion heater helps you to save energy and money by ensuring that your hot water tank always has enough hot supply.

Having an immersion heater timer means that you won’t have to worry about wasting electricity either – as it gives your tank a controlled amount of heating, rather than keeping it constantly at the maximum temperature.

By using a good quality timer, most types will last for many years before they begin to show signs of wear and tear and need replacing.

Another benefit of having an immersion heater timer is that it gives you a lot of control over when your immersion heater comes on and, most importantly, goes off. Most models come with a choice of 24 or even 48-hour timers which means that you can pick the times during the week when you need hot water first and foremost – to have an immediate supply (for example, if you want to quickly run a bath) as opposed to having it on all the time.

Besides energy savings, immersion heater timers can also:

  • Increase the lifespan of your tank heater as well as improve performance.
  • Save you money with electricity bill savings because you can program it to heat water at specific times and on certain days, which means that energy from your central heating system will not be wasted when no one is around to use hot water for bathing or washing clothes. This in turn helps you save a lot of money over time.
  • Prevent scalding accidents as children cannot switch on immersion heaters without supervision.
  • Provide additional security by automatically turning off the immersion heater if there is a power cut or interruption in supply. This is especially useful for homes that have elderly residents living alone who may forget to turn off their immersion heat before.

Things you should know about timers

Though immersion heater timers are simple devices you also need to know few things about them. One of the most important things is that they should be installed by a professional electrician. Also, you need to make sure that the timer has the right wattage.

However, as long as you are careful and do your research then an immersion heater timer can greatly improve your home’s efficiency and energy-saving measures which will ultimately lead to significant savings on your electricity bill.

You should also know that you do not need to remember turning on your immersion heater timer since it has an inbuilt memory feature. You do not even have to get off your bed and set the timer because you can do it with a click of a button. Also, timers are also energy-saving devices because after they have reached the target temperature level, they will go off by themselves once again saving electricity.

It is best if you spend some time investigating installing these devices at home because eventually, you will be able to save more money than any other way or method that would cost less effort and work compared with using an immersion heater timer.


Can I put a timer on my immersion heater?

One of the most commonly asked questions regarding timers is if it is safe to have this device on an immersion heater. The answer is a big yes because by installing one of these at your home you can be assured that the temperature will remain constant and also, can be set automatically to change depending on the events in your life. You can expect maximum convenience with these devices because they do not need any professional help for installation plus they are interconnected with existing wiring thus no need for additional components or circuits.

Should I leave my immersion heater on all the time?

The purpose of installing a timer is to give convenience and if you will be using this device all the time, why install one then? It is better to leave it on when needed and turned off the rest of the time.

If possible at your house, set the time for around half an hour or more than that but make sure that the temperature would not exceed 150 Celsius so as not to cause damage.

What happens if immersion is left on?

If you left the immersion on, it will heat the water that is in contact with it to a high temperature and could cause damage to your home as well as to your device.

How to use an immersion heater timer correctly?

Assuming that you are using it all the time but only for a small period of time, again if possible set the timer for half an hour or even longer so as not to cause damage and burnout. If no timer is available, then you can set a stopwatch on your phone and start it when needed then turn it off manually. Please make sure that water does not boil inside and outside of the bucket.


I hope this guide helps you understand how immersion heater timers work and shows why they are so valuable in controlling costs by reducing electricity consumption! Best of luck.

References: How Heating Controls affect home energy demand


I am John Oakley. I love to share tips and reviews on products to keep our homes warm and comfortable.

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