How to remove radiator sludge

This video will tell you how to remove radiator sludge from a radiator. To tell if you have sludge in your radiator turn your heating system on and if said radiator only gets hot at the top and not at the bottom then you likely have sludge in it. We will tell you how to isolate the radiator, remove it from the wall and hose it down outside removing and the sludge and debris.

If the video above didn't help you out, then read on!

There are a few different options for removing radiator sludge. The professionals prefer a power flusher (see them as a hoover of the heating system). These are expensive pieces of kit and lets face it, you aren't going to buy one for your house. 

So how do you remove radiator sludge from your heating system without having to call a plumber?

Firstly Identify the radiator or radiators that are having a problem. Generally radiators that have sludge in them are cold AT THE BOTTOM. If the radiator is cold at the top, the problem could be air. Check our article on bleeding air from a radiator.

Follow the next steps individually for each problem radiator.

1. Shut of the TRV (thermostatic radiator valve) and lockshield at each end. Sometimes there will only be lockshields. It doesn't matter, shut off the radiator. Turn the heating system off.

2. Open the air bleed valve at the top and dissipate any pressure from the rad. Also this is when we check that the radiator valves are holding closed. If there's still water trickling in 10 minutes, you've got a problem with a radiator valve.

3. Shut the air vent once it's stopped running.

4. Pop a towel and a shallow pan under each end of the radiator. Use a pair of grips and an adjustable spanner to slacken of the radiator valve. Drain the radiator water into the pan. Do this until the radiator is empty.

5. Fully slacken the nuts on the radiator and remove.Take it outside where your hose awaits.

6. Most hoses will push over the radiator valve's spigot. Open the hose full bore and flush out of the other end down a drain. Use a rubber hammer to move any really stuck sludge. 

7. Then flush from the other end. Do the same as above. 

8. Remove air vents on the rad and flush those. Basically just flush every which way you can.

9. Once running clear, pop the radiator back on the wall and re-tighten the nuts. Open the radiator valves. Top up any pressure lost (on pressurised systems 1 bar cold) and turn the heating system back on. 

Test for operation, hopefully the radiators will get lovely and hot. Now you need to think about why there is sludge in your radiators. Usually you need to add more inhibitor to the heating system and a magnetic filter. Check our video on adding inhibitor here.