Heating·10 Jul 2026 · 3 min read
By Mohammed Miah, Gas Safe registered heating engineer
A magnetic filter is a small canister fitted into the pipework near your boiler. As water circulates through your heating system, the filter uses a magnet to capture iron oxide (rust) particles and other debris before they can reach the boiler's internal components.
Without one, that debris circulates freely and gradually wears down the heat exchanger and pump, two of the more expensive parts to replace.
Most boiler manufacturers now require a magnetic filter to be fitted as a condition of the warranty, because it's such an effective, low-cost way of protecting the boiler. It needs an occasional clean-out, usually done as part of your annual service, but otherwise needs no attention.
