Worchester Heat Slave 26/32

[DustyM]

Chaps,

Been out to a Worchester boiler today; customer reported that the boiler wasn't heating the upstairs radiators and underfloor heating (it's installed in a holiday barn), and that the boiler had tripped it's over heat thermostat a couple of times. The owner also informs me that the boiler has also caused the main RCB to operate and that his sparky had tested everything and stated it was the boiler shorting to earth.

I started with the thermostats, checking that they were operating and that the respective relays were doing their thing; all seems ok. Ran boiler for ages on full CH and running as much DHW as I could; but the boiler was not tripping anything. Confirmed that the diverter valve is operating when calling for CH, and prioritising for DHW when called for - all ok. Give the fact that the upstairs heating isn't working, I then checked the pump out, which incidentally is running red hot; it doesn't appear seized, capacitor looks ok but, if I take a resistance readings across the terminals when the damn things is rede hot, I'm getting an open circuit, when I should be getting a resistance readings of the windings at least.

So, am I correct in thinking it's the pump, even though it's not seized, and the capacitor looks ok; someones advice and wisdom, more than welcomed !!

 

[Barry98]

did you undo the nut on the front of the pump and stick your screwdriver in to check it is actually turning

 

[DustyM]

Yes, it seems to be turing freely; but that can also mean impeller failure yes?

 

[diamondgas]

Open circuit is a knackered pump windings for sure! Have had pumps only trip electrics when hot! It's like a connection is fine cold but then when heated shorts to earth!

 

[DustyM]

Diamond Gas; thanks for that, you've confirmed my thoughts exactly; the pump is ok when cool, but the windings are breaking down when hot and shorting out to earth! Thanks mate.

 

[diamondgas]

Diamond Gas; thanks for that, you've confirmed my thoughts exactly; the pump is ok when cool, but the windings are breaking down when hot and shorting out to earth! Thanks mate.

You're welcome. I've had it happens with gas valve solonoids too! Does ya head in trying to get to the bottom of that fault!

 

[Dotty]

I agree, those are hateful faults. Everything buzzes out ok, you turn it all on and it works. You're there thinking someone just likes seeing you when suddenly bang, it all drops out and you're left scratching your head in a slightly confuddled manner.

 

[DustyM]

Yes, but it's the act of being confuddled, followed by the flashes of inspiration that make this job worth while - for me anyhow; solving the problems is most satisfying me thinks.......:lightbulb:

 

[jtsplumbing]

Getting paid is the most satisfying for me !!