radiators

[jasong]

i leave my heating on all the time but it makes a lot of noise in the night like a knocking sound why is this

[Sparky]

If you have a conventional central heating system (i.e. one with a header tank and cylinder, not a combi-boiler) try putting a bottle of corrosion inhibitor into the header tank. This should gradually remove gas bubbles from the circulating water and improve the lifespan of your boiler, pipework and radiators, as well as making it quieter. Repeat annually. You can buy this product at any plumbing shop or DIY superstore. Do not, under any circumstances, pour this chemical into your cold water storage tank (the big one). Consult a plumber if you're not sure.

[KARL]

The answer you have received makes the correct proviso and is on the correct track, but there may be something to watch out for here. It is quite possible that you already have a sludge build-up in the system which an inhibitor would arrest (no more created) but not remove. You could try draining some of the circulating water from your boiler (will probably have a drain point) to see if it is black with sludge. If so drain off until water clears, but there will likely be some in every radiator as well. The proper approach is to flush the whole system with a proprietory agent (follow instructions), then refill with inhibitor added to the water. All depends on the level of this problem. If no sludge, use additive straight away, and unless your system leaks you should not need to top up annually (annually drain off a little fluid into a jar, add steel wool tuft and see if it rusts within a few days - if it does the solution needs more inhibitor).

[Swaden]

Sounds like you have a sluged up system.

[jasong]

could you tell me how to cure this  ps it is a combi boiler