central heating

[network]

some of the radiators in my house are really hot, while others are stone cold, even though the pump ( myson compact cp63) and pipes in my airing cupboard are red hot. The hot water is also cold. I've tried bleeding the radiators, but they are all fine. The boiler seems to be fine and the pilot light is on. Does any one have any ideas?

[beckyboo]

Sounds like an air lock. Try turning off the hot ones and hope this will push the aitr out.

[Tweed]

Are both valves open? One valve is to turn the radiator on and off and the other one is fixed, usually set at the time of installation to balance the system. Balancing adjusts the flow through the radiator to control the ambient temperature of the room. It could also be sludge in the system, which can be removed by draining the system a few times and running a chemical cleaner through it.

[landie]

Is it the upstairs rads which are hot, I suspect that if it is the case the hot water is rising naturally to that level.

If the pump is working, both the input and output pipes should be equally hot. If they're not I suspect the pump is not turning, a sharp tap with a mallet might solve that.

If the pump is working it may be that you have a valve closed somewhere. My system has a non-return (one-way) valve and this caused me a similar problem a couple of years ago, upstairs rads were hot and downstairs not. Once the valve had been replaced everything was fine.