On Sun, 24 Sep 2006 09:47:38 +0000, Brian Reay wrote:

I'm having a problem with our CH. Upstairs rads and hot water are fine,
downstairs rads are very slow to heat up (even with all other rads off). No
air in system, as far as I can tell and system was nicely balanced last
winter and worked fine- ie the problem probably isn't balancing.

Pump seems to be running- there is a slight vibration which you normally get
when it is BUT the only time I've seen this sort of thing before was when
the pump had failed (in our previous house).

So, I'm thinking the pump may be rotating but maybe the impellor is shot in
some way (broken shaft maybe). Is this a "normal" failure mode?

Yes it's one of the less common failure modes.

The major ones IME a
Electrical earth fault.
Jams and continues to do so every time it stops.




--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards