How Much Does An Immersion Heater Cost?

How Much Does An Immersion Heater Cost?

Written by  John Davies
Last updated: January 16, 2024

It depends. Do you need a full installation or just a replacement? Full installation costs around £2,000, while Immersion heater replacement costs just £240 to £290. There will be variations, but those are pretty accurate estimates. 

So, here is a simple answer to your inquiry- Immersion heaters cost around £290 to £2,000, depending on the job. If you want a more nuanced answer, you must keep reading because many factors affect immersion heater costs. We intend to explain them in this article. We will also cover details like types, advantages and disadvantages of immersion heaters.

Immersion Heater Costs: Full breakdown

Job TypeAverage Total Cost
immersion heater cost (full installation) £2,000
Immersion heater replacement cost (single heating element)£240
Immersion heater replacement cost (replacing two heating elements)£290

Types of Immersion Heaters & Their Costs

Immersion Heater TypeImmersion Heater Cost
Flange immersion heater£15-£20
In-line immersion heater£20-£25
Screw plug immersion heater£30-£40
Over-the-side immersion heater£40-£60

What Is an Immersion Heater? And How Does an Immersion Heater Work?

An immersion heater is like an electric kettle. There is a container of water (called the hot water cylinder or tank), a heating element and an electrical power source. The heating element is immersed in water and connected to electricity. When switched on, the heater converts electrical energy to heat, causing the water (in the cylinder) to get hot.

This process heats the entire content of the cylinder. Therefore, it could take a while before hot water is available. In most immersion heaters, it takes about 1 to 2 hours. However, heating speed depends on the heater’s capacity and the cylinder’s size.

Some immersion heaters have more than one heating element. These immersion heaters cost more, but they are also faster. One heating element is usually installed at the bottom of the tank, while the other is at the top. The one at the bottom is the primary heating element, while the one at the top kicks in when you push the booster button.

Most immersion heaters also have insulation, timers and thermostats. These three add to immersion heater costs, but they improve performance. Insulation reduces heat loss, which increases heating speed and keeps water hot for longer.

A timer allows you to program the immersion heater to start at specific times. This reduces waiting time. A thermostat allows you to program the heater to stop at a desired water temperature. The result of this is a reduction in energy wastage. 

In other words, insulation, timers and thermostats reduce operating costs, improve energy efficiency and increase control options.

Factors Affecting Immersion Heater Costs

Here are the factors that affect immersion heater costs. Whether you are trying to replace a heating element or install a complete immersion heater system, these factors will affect cost.

Job Type

There are two main categories of immersion heater jobs: full installation and replacement. Full installation is the process of installing an immersion heater system from scratch.  It involves installing the hot water cylinder, heating elements, electric connection and water pipes. On the other hand, immersion heater replacement involves replacing heating elements.

We have covered the prices of each job type on our immersion heater costs table. Complete immersion heater installation costs £2,000, while immersion heater replacement costs £240 for a single heating element and £290 for dual heating elements. This is how job type affects immersion heater costs. 

Heater Type and Size

Immersion heater costs will also vary according to the type and size of the heater. For example, the four main types of immersion heaters are flange, in-line, screw-plug and over-the-side heaters. Flange heaters are the most affordable, while over-the-side heaters are the most expensive.

Another way to classify immersion heaters is to consider the building material of their heating elements. Options included copper, titanium, stainless steel, and cast iron. Titanium immersion heaters are pricy, while copper ones are more affordable.

As for the matter of heater size, that is very easy to understand. Bigger immersion heaters cost more than smaller ones. They cost more to install, operate and repair. However, they will have higher heating capacity and speed.

Job Complexities

The more complex a job is, the more money it will cost. That’s why immersion heater replacement costs less than complete installation. However, even within the same job type, complications could blow up immersion heater costs.

For example, let’s assume you hire a heating engineer to replace a heating element in your immersion heater. Then, the engineer experiences difficulty accessing or draining the cylinder. Issues like these could affect immersion heater costs because the engineer might want to charge more.

Additional Tasks

Let’s go back to our anecdote. Let’s assume you and the heating engineer have agreed on a price to replace your immersion heater. Then, the engineer inspects your heater and discovers you don’t need immersion heater replacement alone. You also need to descale or even replace the cylinder. 

Descaling alone costs around £300. Tank replacement will cost more. Either way, this will increase immersion heater replacement costs. Other additional tasks of immersion heater replacement include electrical repairs and the installation or replacement of the insulation jackets, timers and thermostats. 

These tasks are not part of the main project. However, they are crucial to the performance of an immersion heater. So, they are essential. That’s why you should let your heating engineer inspect the heater and make suggestions. Just remember that it will affect immersion heater replacement costs.

Differences Between Companies

Immersion heater costs will also vary depending on whom you hire. Some companies’ services are more expensive than their competitors. Some companies’ services are also better. That’s why you must conduct research and compare quotes before hiring. However, regardless of differences, most quotes will be around our estimated immersion heater costs.

Your Location

Your location also affects immersion heater costs. Labour and supply costs are higher in big cities and Southern UK. So, expect higher immersion heater costs in those areas. You should also expect higher prices if the engineer is coming from afar. Most might charge more to cover transportation costs.

How Much Does It Cost to Run an Immersion Heater?

Operating cost varies, depending on the wattage of the heater. It costs 50p per hour to run an immersion heater of 3kw and 80p per hour to run a heater of 6kw. This high running cost is one of the main disadvantages of immersion heaters.

Do You Need an Immersion Heater?

Immersion heaters aren’t perfect. They are not the right choice for everyone and every household. So, to help you make the right choice, we have compiled the advantages and disadvantages of immersion heaters. We have also created a checklist to help you decide if you need an immersion heater.

Advantages of Immersion Heaters

An Energy-Efficient Way to Heat Large Quantities of Water

If you want to heat a large water tank, immersion heaters are a great choice. They are highly energy-efficient and cost-effective when it comes to this.

Low Maintenance

Immersion heaters are low maintenance. They only need simple checks to ensure everything works properly. The only professional care they need is regular service and descaling.

Affordable and Easy to Install

The structure of an immersion heater is simple. It’s just a water tank, a heating element(s) and an electrical connection. That’s why immersion heaters cost less than other heaters. It’s also why they are so easy to install and use

Reliable and Versatile

These two are also due to the simplicity of an immersion heater’s structural setup. There aren’t any complex mechanical parts. Therefore, immersion heaters rarely fail and can function alongside another heating system. People use immersion heaters as backup or hot water sources for radiators and combi boilers.  

Disadvantages of Immersion Heaters

High Operating Cost

We have already discussed how much it costs to run an immersion heater. So, you already know about this disadvantage. The issue is even more glaring when you compare immersion heaters to other heaters on the market today.

However, the story does change when it comes to installation costs alone. Here, immersion heaters cost less than the alternatives. Besides, there are ways to reduce the operating cost of immersion heaters. You can:

  • Add an insulation jacket, timer and thermostat (we already discussed how these help)
  • Use solar energy to power the immersion heater
  • Plan your hot water needs for around the same time. As a result, you won’t have to run the heater several times daily. This won’t just reduce operating costs. It will also increase the life span of the heater.

Low Environmental Friendliness

As a result of the high operating costs, immersion heaters aren’t environmentally friendly. Too much energy is wasted heating more hot water than needed. Plus, other heaters (modern ones) are much more energy-efficient and environmentally friendly.

Not Multi-functional

Most modern heaters don’t just heat water. They also serve as home heating systems. Immersion heaters aren’t like that. They only provide hot water.

Slow Heating Speed

It takes one to two hours to get hot water from an immersion heater. That waiting period can be frustrating, although you can use a timer to reduce this inconvenience. Simply set the timer to automatically switch on the heater an hour or two before you need the hot water (like bath time).


The lifespan of an immersion heater is just three to five years, even with good maintenance. Some alternatives can last for up to ten years. However, remember that immersion heater replacement costs are relatively low.

Do You Need an Immersion Heater? The Checklist

Here are some signs that you need an immersion heater.

  • You need to heat a large quantity of water
  • You don’t mind waiting 1-2 hours for hot water
  •  You don’t need to heat water several times daily
  • You need an affordable backup or hot water source for your main heater

Types of Immersion Heaters

Flange Heaters

Flange heaters cost relatively less than the others. They are also easy to install and versatile. Lastly, they are high-capacity and highly resistant to corrosion.   

In-line Heaters (AKA Circulation heaters)

In-line heaters are easy to install and efficient, although they are relatively high maintenance. They use indirect heating.

Screw Plug Heaters

Screw plug heaters are versatile, low maintenance and energy efficient. They are resistant to leaks, but the heating element takes up too much room.

Over the Side Heaters

These types of immersion heaters are compact. The heating element takes up little space and is mounted on the cylinder’s side, bottom or top. An over-the-side heater is also easy to maintain, service or replace. The main disadvantage is the relatively longer heating time.


Immersion heaters cost around £240 to £2,000 depending on the job type and other factors. Immersion heater replacement costs £240 to £290, while installation costs £2,000. These prices are for professional services by qualified heating engineers or plumbers. They don’t apply to DIY jobs. 

DIY immersion heater replacement costs lower because you won’t have to pay for labour (about £50 to £75 per hour). As for DIY immersion heater insulation, we don’t recommend it. In fact, we don’t even recommend DIY immersion heater replacement unless you have enough experience. Besides, there are lots of benefits to hiring a professional. They serve other functions besides removing and replacing heating elements.   


How Long Will an Immersion Heater Last?

An average immersion heater will last for three to five years, depending on usage, maintenance and the type of water involved. Hard water contains lime scale, which can corrode and damage the heating element.

How Long Do Immersion Heater Replacement Jobs Take?

Immersion heater replacement takes 2 to 3 hours

How Will You Know When an Immersion Heater Needs Replacement?

Signs include:

  • Slower heating time
  • Hot water is getting cold too quickly
  • Leaks
  • Unusual noises

Call a heating engineer when you notice these issues, but let them examine and diagnose the heater themselves. 

What Are Some Energy-Efficient Alternatives to Immersion Heaters?

Options included condensing gas boilers, solar thermal systems and air-source heat pumps. Remember that immersion heaters cost less than these three when it comes to installation alone.

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.

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