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Maintenance4 min read10 July 2025

Magnetic Filters: Why Every Heating System Needs One

A magnetic filter is one of the cheapest and most effective ways to protect your boiler and heating system. Here's why every home should have one.

Magnetic Filters: Why Every Heating System Needs One

What Is a Magnetic Filter?

A magnetic filter (also called a magnetic system filter or MagnaClean) is a device fitted to your central heating pipework — usually close to the boiler — that uses a powerful magnet to capture iron oxide particles (sludge/magnetite) as they circulate in the heating water.

The most well-known brand is Adey MagnaClean, but there are several quality alternatives including Fernox TF1 and Spirotech SpiroTrap.

Why Does This Matter?

As your central heating system ages, iron oxide particles form naturally through the corrosion of steel components (particularly radiators and pipework). These particles circulate continuously in the system water.

Without a filter, this magnetite:

  • **Coats the heat exchanger** inside your boiler, reducing efficiency
  • **Wears out the pump** through abrasion
  • **Settles in radiators** as sludge, causing cold patches
  • **Blocks small-bore pipework and valves**
  • **Reduces overall system efficiency**, costing you more to heat your home

    • What Does a Magnetic Filter Do?

    The magnet inside the filter body attracts and holds iron oxide particles as the water flows past. Instead of circulating and causing damage, the sludge is trapped and held safely within the filter.

    At each annual boiler service, the engineer opens the filter and cleans out the accumulated sludge — keeping the system clean year after year.

    Benefits of Fitting a Magnetic Filter

  • **Protects the boiler** from sludge damage and premature failure
  • **Maintains radiator efficiency** — no cold spots from settled sludge
  • **Reduces energy bills** — a clean heat exchanger transfers heat more efficiently
  • **Often required for boiler warranty** — most major boiler manufacturers now require a magnetic filter as a warranty condition
  • **One-time low cost** — filters typically cost £50–£100 installed; serviced annually at no extra cost as part of your regular boiler service

    • When Should You Fit One?

    Ideally at the time of a new boiler installation. If your system doesn't have one, it's worth fitting at your next service appointment.

    Halo Heating fits magnetic filters on every new boiler installation as standard. Call 01483 676108 to arrange a filter fitting or boiler service.

    Need Professional Help?

    Our Gas Safe registered engineers cover Surrey and surrounding areas. Call for a free quote or to book an engineer.

    Call 01483 676108