central heating problem

[goboman]

Help please with ch prob, i have v hot water coming into expansion tank in the loft but radiators ok apart from 1 warm out of 10 hot water ok water returning to expansion tank is contant stream and v fast but tank not overflowing.

 

[gavinda]

blocked cold feed and vent more than likely. cut and clear, then flush with restorer .

 

[Tipper]

If the tank has a constant flow of water then how can the cold feed and vent be blocked?

 

[gavinda]

the blockage lies between the cold feed and vent. this means its easier to pump over through the header tank. this inturn oxybenates the waters excacerbating the problem. system will no doubt be in need of a good flush too. this blockage can be proved with a good strong magnet around the cf/ov pipes, though it.ll possibly stick all over the heating pipes.

 

[DP]

Blockage usually takes place in the return tee at the cylinder on the expansion pipe. This blockage often greatly impedes flow of water (e.g. when bleeding rads).

Pump over is cause of incorrect location of pump i.e. vent is at high pressure in relation to feed pipe, so water discharges from the vent to enter the system via the feed & expansion pipe. A blockage at the aforementioned tee will restrict water flow (i.e. pump over no more)

Water could dribble from the vent pipe as a result of expansion that cannot go up the blocked feed pipe.

Above is my understanding but then again I am often wrong (as the wife keeps saying)

 

[gavinda]

Blockage usually takes place in the return tee at the cylinder on the expansion pipe. This blockage often greatly impedes flow of water (e.g. when bleeding rads).

as you say , wrong location.. the expansion should be well before that, before the pump and the feed.