What does a magnetic filter do?

What does it do?

A magnetic filter:

• Removes magnetic debris - Attracts and traps rust, magnetite (black sludge), and other metal particles
• Protects your boiler - Prevents debris from entering and damaging the boiler's heat exchanger
• Keeps the system clean - Reduces sludge build-up in radiators and pipes
• Improves efficiency - Clean water flows better, so your boiler works more efficiently
• Extends boiler life - Reduces wear and tear on boiler components

The filter sits in the pipework and the water flows through it, with magnets inside capturing any magnetic particles.

What is magnetite?

Magnetite is a black, sludge-like substance that forms in heating systems. It's created when:

• Oxygen reacts with metal - In your radiators and pipes
• Rust forms - Over time, metal components rust
• Debris builds up - Tiny particles accumulate in the water

Magnetite can:

• Block pipes and radiators - Reducing water flow
• Damage boiler components - Especially the heat exchanger
• Reduce efficiency - Makes your boiler work harder
• Cause breakdowns - Can lead to expensive repairs

A magnetic filter helps prevent magnetite from causing these problems.

What are the benefits?

Installing a magnetic filter offers several benefits:

Protects your boiler:

• Prevents debris from entering the boiler
• Reduces risk of breakdowns
• Extends boiler lifespan

Improves efficiency:

• Clean water flows better
• Boiler doesn't have to work as hard
• Can reduce energy bills

Reduces maintenance:

• Less need for powerflushing
• System stays cleaner for longer
• Fewer call-outs for blocked systems

Cost-effective:

• Relatively inexpensive to install
• Can save money on repairs and maintenance
• May be required for boiler warranty

Do I need one?

A magnetic filter is recommended if:

• You have a new boiler - Many manufacturers recommend or require one
• Your system is old - Older systems are more prone to sludge build-up
• You've had problems - If you've had blocked radiators or boiler issues
• You want protection - Peace of mind that your boiler is protected

Some boiler manufacturers require a magnetic filter for warranty purposes, so check your boiler's requirements.

Where is it installed?

A magnetic filter is usually installed:

• On the return pipe - The pipe that brings water back to the boiler
• Near the boiler - Close to where it's easy to access for maintenance
• By a qualified engineer - Should be installed professionally

The exact location depends on your system layout, but it needs to be in the main flow of water through your heating system.

How is it maintained?

Magnetic filters need regular maintenance:

Cleaning:

• Every 6-12 months - Should be cleaned regularly
• Remove the magnet - Take out the magnetic core
• Clean off debris - Wipe or wash off the collected particles
• Replace and reseal - Put it back and ensure it's sealed properly

Professional service:

• Some filters can be serviced during annual boiler service
• Your engineer can check and clean it
• May need replacing after several years

The maintenance is relatively simple, but if you're not confident, get an engineer to do it.

How much does it cost?

Magnetic filters typically cost:

• £100-£200 - For the filter itself
• £100-£150 - For installation (varies by engineer)
• Total: £200-£350 - For supply and fit

This is a one-off cost, and the filter should last many years with regular maintenance.

Can I install one myself?

Installing a magnetic filter requires:

• Plumbing skills - Cutting pipes, making connections
• System knowledge - Understanding your heating system
• Proper tools - Pipe cutters, fittings, etc.

It's generally recommended to have a qualified engineer install it to ensure it's done correctly and safely. Incorrect installation could cause leaks or system problems.

Summary

• A magnetic filter removes rust, magnetite, and other magnetic debris from your heating system
• It protects your boiler by preventing debris from entering and damaging components
• Benefits include improved efficiency, reduced maintenance, and extended boiler life
• Recommended for new boilers, old systems, or if you've had problems
• Installed on the return pipe near the boiler by a qualified engineer
• Needs cleaning every 6-12 months to remove collected debris
• Costs around £200-£350 for supply and installation
• Should be installed professionally to ensure it works correctly and safely