Magnetic filters and scale reducers: why your boiler needs both

Two small, inexpensive devices do most of the work in protecting a new boiler for the long haul, and they're often confused with each other because they sound similar. They protect against two completely different problems.

Magnetic filters: protecting against your existing system

A magnetic filter sits in the pipework near the boiler and catches rust and sludge circulating in your central heating loop, the closed system of pipes and radiators that's often years or decades old by the time a new boiler goes in. Without one, that debris circulates straight through the new boiler's heat exchanger, the most expensive part to replace, and is the leading cause of early failures and warranty claims we see.

We fit a magnetic filter as standard on every boiler we install, on every package. If your existing system is particularly old or sludged, see our guide on power flush vs MagnaCleanse vs a standard clean for whether it's worth cleaning the system properly before the filter goes to work.

Scale reducers: protecting against your water supply

A scale reducer is different again. It's fitted on the incoming mains water supply, the fresh water that becomes your hot water, and reduces limescale building up inside the boiler's heat exchanger as it heats that water. This is a separate problem from sludge in the heating loop, and it only matters in hard water areas.

London and most of the surrounding area sit in a hard water region, so limescale is a genuine, ongoing risk rather than a rare edge case. Left unchecked, it reduces efficiency and can shorten the life of the heat exchanger, and several manufacturers make fitting one a condition of the warranty in hard water areas.

A scale reducer is fitted as standard on our Standard and Premium packages. If you've chosen Essential, ask us to add one at survey, it's a small extra cost that protects a much larger investment.

Do you need both?

Across the areas we cover, almost always yes: a magnetic filter for what's already in your pipework, a scale reducer for what's coming in through the mains. Neither replaces the other. Get a fixed price that includes what your home needs. Get your instant boiler quote.