How to service a solar thermal system is a really common question asked by many of our customers and prospective customers. Unfortunately there isn't really a definitive answer. It depends on how technically minded you are and how much peace of mind you need. So here are some guidelines:

1. Solar thermal heating systems are low maintenance systems which require little regular planned servicing. The only moving part is the pump which is a relatively low cost item (less than £100) and reasonably easy to change. The electronic controllers sometimes fail, albeit rarely, and these are also reasonably inexpensive and easy to change.

2. Keep an eye on your system. The main thing to watch out for is fluid leaks – especially the antifreeze which smells rather strong. If there is a leak contact your installer.

3. Make sure your solar system is doing what you expect. If the weather is sunny and your hot water cylinder is cold you may wish to look a bit deeper – unless of course you have just enjoyed a deep, relaxing bath!

4. Similarly if the pump is running but the solar pipework is cold you may have an airlock which your installer can sort out for you.

5. One thing you may wish to look at from time to time (say once a month) is the pressure of the system which should between 1 and 2 bar – although it can drop as low as 0.5 bar in cold weather as the fluid contracts and as high as 3 or 4 bar if the system gets very hot. This is nothing to worry about but if the system falls below 0.5 bar and stays there, contact your installer.

6. The antifreeze in your system will degrade over time and need replacing eventually. However bear in mind that the antifreeze is designed to cope with temperatures as low as -28C; the coldest temperature ever recorded in the UK is -27C and that was before climate change. So the system should be fine for at least 10 years. One of our suppliers installed a system at his house in the north-east of England in the late 1970s and has never needed to change the antifreeze.

7. If you want peace of mind, installers like us will perform an annual service to check everything is working as it should.

I hope that this helps and that you get years of free energy from your solar thermal system.

Photo by Elsie esq.

About the author: Paul Hutchens is founder and director of Eco2Solar, which installs solar systems around the UK.

If you have a question about anything in the above blog, please ask it in the comments section below.