Cleaning out radiators - What is needed?

[Chris]

The house was built in 1975 with an oil-fired central-heating system. About five years ago we changed over to gas and had a combi boiler installed. (Pressurised - sealed system.)

What should I do about maintenance for the radiator system? Flushing etc.? (It's a microbore system, with a pair of quarter-inch pipes to each radiator.)

When does it need doing? How often? What needs to be done?

[Roger Mills]

If your system has adequate corrosion inhibitor, and if there are no symptoms of sludge[1], it may *never* need flushing. If it ain't broke, don't fix it!

[1] when sludge builds up in a radiator, you get a triangular cold patch - all across the bottom and getting narrower as you move up. If your rads are uniformly hot all over, they're unlikely to be sludged.

If if *does* need flushing, by far the most effective means (other than using very expensive in-situ flushing equipment) is to remove the radiators, and take then outside and give them a thorough wash out with a hose pipe until the water runs clear. You can then use the filling loop to flush the pipes out while the rads are off.

But this is not the time of year to do any of that!