Central Heating

[daveking]

Why does my heating creak and bang ever time the boiler and pump come on? I've bleed all the air out of the radiators but still seem to get air in the bathroom one.

[Dassie]

Probably an airlock in your hot water cylinder pipe.

[buildersmate]

It creaks and bangs because the pipes expand when the pump starts pumping hot water in them. The pipes move slightly on the wooden joists they sit on, under the floorboards. Very difficult to irradicate.
If you are continuing to get 'air' in the system after you have bled them, it probably isn't air at all, but hydrogen, a byproduct of gradual corrosion inside the system. The CH water gradually attacks the steel radiators, producing black magnetite sludge (which sits at the base of the radiator) and hydrogen gas. Over perhaps 10 years, the rads would corrode through. Have you got the right amount of corrosion inhibitor in the closed CH system? This stops it.
The two problems you describe are unconnected to one another.
PS - Why is this posted in Travel?

[gasman]

As buildersmate quite rightly points out and is in my oppinion spot on with his reply. Then you will find that it seems to be always the bathroom rad, because it is probably the tallest and highest rad in the system, and so this is where the hydrogen will eventualy settle as it rises through your system.

[purplecarrot]

Very simple; quick fix and wont cost a penny.

Turn the pump speed down, this is done by turning the large matal screw on the front of your pump to slow it down a little. Always try the simple and cheapest option before the expensive. My bathroom radiator always gets air in it, it is just something I have to deal with. Never had the problem until some wally plumber decided to put radiator thermostats on every one in the house execpt bathroom.
If yours is the same the Eureka!

Anyway try this first