Blog>Cost Guides>Cost to fit a thermostat to your hot water cylinder
Last updated: 11 March 2024
Cost to fit a thermostat to your hot water cylinder
A hot water cylinder's job is to provide a ready hot water supply for showers, washing and other household chores. The cylinder contains a lot of pre-heated water, so it’s all set for when you want it.

Fitting a hot water cylinder may seem simple to an expert, but for a DIYer it can be a nightmare. If you're comfortable with the plumbing skills required to swap your existing thermostat for a new one, then by all means have a go yourself.
If you think a bigger job might be needed - such as moving a hot water cylinder - it's best to seek the help of a competent professional.
What is a thermostat?
Hot water cylinder thermostats work by turning your heating on and off from the boiler to the hot water cylinder. They are generally surface mounted or attached to the outside of the hot water cylinder and the temperature should be set to eradicate any harmful bacteria in the water, typically between 60 and 65 degrees.
How much does it cost to fit a thermostat to a hot water cylinder?
To ensure the job’s done properly, we recommend hiring a plumber. In this case, it’ll cost closer to £110 for installing a new thermostat to your hot water cylinder. The part itself can cost anything from £20 on top of the installation cost.
See the tradespeople we've checked and recommend for your job
How to fit a thermostat to a hot water cylinder
We recommend contacting a professional to fit a thermostat to your hot water cylinder.
Hot water cylinder thermostat quotes
If you’re trying to find out how much it'll cost to fit a hot water cylinder, you may need to contact a hot water engineer in your local area. We advise contacting at least three such tradespeople for price estimates so you can get the best rate.
If you aren’t sure where to start, you could use our ‘Request a quote’ tool to make life easier. Just enter the details of the job and post it. Then, you’ll be contacted by hot water engineers local to you with their quotes.

FAQs
How do you change a thermostat on a hot water cylinder?
Fitting hot water cylinder thermostats is straightforward. You can do this by following the instructions mentioned above.
Where should a thermostat be placed on a hot water cylinder?
Typically, a thermostat is installed roughly one-third of the way up the hot water cylinder so it can measure the water temperature efficiently. If it drops under the desired temperature (normally 60-65°C), this triggers the boiler to come on.
Does a hot water cylinder need a thermostat?
Yes, any hot water cylinder will need a thermostat because it helps keep your hot water at the appropriate temperature to avoid wasting energy keeping it warmer than needed.
How do I know if my cylinder thermostat is working?
Signs your hot water thermostat’s faulty include:
The cylinder or airing cupboard feel incredibly hot
Scorching water comes out of the hot water taps
Hot water comes out of the cold taps
You hear ‘bubbling’ or excessive noise coming from the hot water cylinder
You spot steam or moisture in the airing cupboard or roof space
You can test a thermostat’s working using a multimeter. A working thermostat should have a reading of zero or as near to zero as possible. So, if your thermostat doesn't read anything at all, it means it’s broken and needs replacing.
See the tradespeople we've checked and recommend for your job
More Cost Guides
See the tradespeople we've checked and recommend for your job