Excessive rad bleeding

[sambrowne]

Hi all. I have been struggling with my CH since moving into a new house in March. The house is 20yrs old, the boiler (Idal Classic RS50) is newer but still before my time. The problem is that I have to bleed the rads excessively - with two of them they start cooling at the top immediately as soon as I start bleeding the next one.

I have checked the expansion tank in the loft and the doesnt appear to be any overflow coming back in from the vent, and the water in it does not look to be circulating at all . (As for the vent pipe, I am assuming the end of it should not be submerged?)

Any ideas on how to fix this/these problem(s)? Thanks.

 

[oilman]

It's probably corrosion. Add some system cleaner, then drain and flush in a couple of weeks, then add some corrosion inhibitor.

 

[mave]

Go back to your expansion pipe and put your hand over the end to see if it's sucking air. If so you may find that your pump is set too high and turning it down will solve the problem.

Although corrosion can cause the production of gas in the system it is unlikely to produce the amounts that you are experiencing.

 

[sambrowne]

Many thanks. The expansion pipe isn't sucking, so I'll try the cleaner and inhibitor.

 

[DavidArthur]

Do you have thermosatatic valves fitted?
On some valves they must be fitted to the flow and not the return otherwise can cause the rad to fill with air, don't know why thou!