Magnetic filter fitting
A small cylinder on a pipe that saves your boiler a lot of grief.
A magnetic filter sits on the return pipe just before your boiler. As the heating water passes through, a strong magnet pulls out the iron oxide sludge that builds up in steel radiators, and a mesh catches other debris. It stops that muck reaching the boiler's heat exchanger and pump. We fit them on new boilers as standard and on existing systems that need protecting.
Why a magnetic filter matters
Steel radiators slowly corrode from the inside. The tiny black particles that come off are magnetic, and they collect wherever the water slows down: the bottom of radiators, the pump and the narrow waterways in the boiler.
A filter catches them in one place where they can be emptied out at the annual service. Cleaner water means the boiler, pump and valves are not working through sludge, and sludge is a common cause of breakdowns.
When to fit one
If your system has never been cleaned, a filter alone will not shift sludge already sitting in the radiators. It will start catching what moves, but a power flush or chemical clean first gives it a fresh start.
- With every new boiler (manufacturers often expect one for the warranty)
- After a power flush, to keep the system clean
- On an older system where a bled radiator runs black
- After a pump or heat exchanger has failed because of debris
- When you add radiators or extend the system
Looking after it
A filter is only useful if someone empties it. We clean it during your annual boiler service: isolate, open, wipe the magnet, refit and top up the inhibitor. It takes a few minutes.
Seeing what comes out is quite satisfying, and it tells us how the system is doing. A filter full of black sludge every year is a sign the system needs more attention.
What is included
- Check of your system water condition
- Magnetic filter fitted on the return pipe near the boiler
- Isolating valves so the filter can be cleaned without draining the system
- Inhibitor topped up
- System refilled, bled and checked for leaks
Magnetic filter fitting FAQs
How long does it take to fit a magnetic filter?
Usually an hour or two on an existing system, depending on how easy it is to get at the pipework under the boiler. On a new boiler installation it is part of the job.
Do I need a magnetic filter with a new boiler?
We fit one as standard. Many manufacturers expect the system to be cleaned and protected for their warranty, and a filter is the simplest way to show it.
How often should a magnetic filter be cleaned?
Once a year is usual, at the boiler service. A dirty system might need it more often at first, and we will tell you if so.
Will a filter fix my cold radiators?
Not on its own. It catches loose debris from now on, but sludge that has already settled in radiators needs a flush or a chemical clean to move it.
Get a fixed price for your home
Tell us about the job and we will arrange a free survey.