How to clean a MagnaClean filter

1. Check whether you should be doing it yourself

ADEY recommends having a MagnaClean filter cleaned by a qualified heating engineer during an annual heating service. That is the safest route, especially if the filter is tight, leaking, boxed in, or close to the boiler.

Do not remove boiler covers, touch gas parts, or open anything you are not confident with. A filter clean is one thing. Fiddling around inside a boiler is not.

2. Turn the heating off and let it cool

Switch the heating off and give the pipework and filter time to cool properly. The filter body and the water inside can be hot.

If the system has just been running, wait. Hot dirty water from a filter is not something you want on your hands or floor.

3. Isolate the filter valves

Close the isolation valves on both sides of the MagnaClean filter. This separates the filter from the rest of the heating system before you open it.

If the valves are stiff, dripping, seized, or unclear, stop there and call a heating engineer. Forcing old valves can quickly turn a tidy job into a leak.

4. Protect the floor and release pressure carefully

Put a towel and a small container under the filter. Depending on the model, you may need to use the vent or drain point to release pressure and catch a small amount of water.

Follow the instructions for your exact MagnaClean model. There are several versions, and the details are not all identical.

5. Remove the magnet assembly

Open the filter as the manufacturer instructions show, then remove the magnet assembly. You will usually see black sludge, known as magnetite, on the sleeve or magnet area.

Keep small parts, seals, washers, and caps safe as you go. They have a habit of rolling somewhere annoying.

6. Clean the magnet and filter body

Use clean water and a non-metallic brush or scraper to remove the sludge from the magnet assembly. Avoid metal tools, as the magnet is strong and the parts can be marked or damaged.

Clean inside the filter body if you can do it without damaging seals or threads. Do not use random chemicals unless the manufacturer instructions say they are suitable.

7. Check the seals before reassembling

Look at the O-rings, washers, threads, and sealing faces before putting the filter back together. If anything is split, flattened, missing, or damaged, it may need a proper service kit.

Reassemble the filter carefully and do not overtighten it. Tight enough to seal is the aim, not tight enough to prove a point.

8. Open the valves and check for leaks

Open the isolation valves again, then check the filter body, lid, drain point, vent, and valve connections for drips. Wipe the filter dry so it is easier to spot fresh leaks.

Some systems may need venting or pressure checking afterwards. If the boiler pressure drops or the filter will not seal, stop and get a heating engineer.

When to call a heating engineer

Call a heating engineer if the filter leaks, the valves will not isolate, the lid will not move, the system pressure changes, the boiler shows a fault, or you are not sure which model you have. To be fair, a clean filter is useful, but a watertight heating system is more useful.