Immersion Heaters Guide & Costs

Immersion Heaters Guide & Costs

John Davies Last updated: July 5, 2023

Immersion heaters are worth considering if you are looking to install a new boiler, either during initial construction or need to upgrade an existing one. However, in most cases, immersion heaters are more suitable as a backup than the household’s primary water heating method.

What is an Immersion Heater?

Immersion heaters are devices that can heat liquid in a tank or container. It can be installed in various ways, including flanged, threaded, or over the side. They are essentially big tea kettles, warming large amounts of liquid.

In some older boilers, they provide the primary source of hot water. However, it can also serve as a helpful backup. Immersion heaters run directly off the electrical power and are not connected to your boiler. Therefore, even when the boiler is broken, the immersion heater will provide you with hot water at the switch of a button.

If the heater is well insulated, the water supply will last for quite a few hours, even after it has been switched off. Therefore, you may be able to get multiple showers out of it without numerous uses.

Another significant advantage of immersion heaters is the ease of operation. They are so straightforward to use that they require nothing more than the flipping of the switch and the thermostat setting. You can even avoid the latter by regulating it with a timer.

What Types of Immersion Heaters are There?

The most common variety of immersion heaters are the flanged ones. This form of installation includes hairpin bent tubular elements incorporated into a flange. An engineer will install the heater by bolting the flange to a nozzle or the tank wall. This is the most adaptable type of immersion heater.

When a flanged immersion heater is challenging to install for one reason or another, a good solution is installing an over-the-side immersion heater. The engineer positions them at the top of the vessel. The natural circulation of the fluid distributes heat evenly.

Through-the-side immersion heaters and screw plug immersion heaters provide other options. With the number of solutions available, an immersion heater can be installed in just about any home.

Who Needs an Immersion Heater?

Immersion heaters are a handy backup (to central heating) and, therefore, in theory, are helpful for everyone. However, the drawback is that heating water with electricity can be several times more expensive than heating it with gas. It does have the notable advantage of requiring less ventilation than a gas unit. However, that does not make up for the higher expense.

Also, immersion heaters are pretty slow. That can make relying on them somewhat inconvenient and also increase the cost. Another final disadvantage is that immersion heaters are less efficient at heating. Therefore, the water may not be as hot as some people like. Some have trouble heating water above 50°C and therefore are not as efficient at killing bacteria as other heater variants.

Therefore, an immersion heater is very useful if you have a primary heating water source and need a reliable backup. Keep in mind that you should not use it unless your primary source of hot water is not working due to the related expenses.

It is deeply inadvisable for anyone looking for one primary source of hot water with no backups. It is also not needed if you don’t mind taking a cold shower or skipping a shower now and then awaiting repairs on the primary water heating source.

How Does an Immersion Heater Work?

Immersion heaters directly treat the water within them and raise its temperature. They usually have a heating element placed directly inside the water. It passes a robust electrical current into the water it is immersed in (hence the name), which substantially raises the liquid’s temperature.

The water tank receives a steady supply of cold water emanating from below the reservoir. The water pushes the water heated by the electrical current out of the immersion heaters cylinder. Due to gravity’s force, the heated water rises to the heater’s top, and the water is then ready for use.

In most newer immersion heaters, a thermostat helps keep the temperature constant so that any time you shower, the water is neither too hot nor too cold. Most units will also include an isolating switch to regulate the connection to the main electrical supply.

If you are getting one installed, make sure to ask for a timer attachment on the tank. Owning an immersion heater that is controlled by an artificial switch is a recipe for disaster. If you or a household member forget it for long periods, you will needlessly pay large electrical bills. The automatic timer will save money while ensuring that you have a regular supply of heated water at your service, ready and loaded for emergencies. You can also set the timer for off-peak hours to save electrical billing expenses.

How Much Do They Cost? Including Installation?

The price of an immersion heater varies according to size and type. The exact price will also depend on the number of rooms in your home, as well as the type of water heating system you have in place.

You will have to buy a hot water storage cylinder separately and hire a professional to complete the installation. However, overall they are relatively inexpensive to install or fix.

To calculate which heater you require, you need to know how many litres of water are necessary and what temperature increase is required to fulfil your domestic needs. Although prices vary, you are probably looking at around £2000 for the installation. Meanwhile, replacing an existing unit will cost far less and run in the £200-250 range.

The main cost associated with an immersion heater is the cost of use rather than installation. If used often, it can quickly become the most expensive item on your electric bill. The most common immersion heaters cost an average household 50p per hour, as they consume about three kilowatts an hour. You should get multiple quotes from trained plumbers before you choose a company to go ahead with the work.

In conclusion, an immersion heater serves as a great backup to your primary heating system. While you may not want to install a new one, consider repairing it or improving it if you have an existing immersion heater infrastructure. You will be happy you did when you desperately need a shower, and something goes wrong.

Email newsletter
Tell us about what you want to learn!
We won’t spam you, we promise!