combi boiler cutting out on central heating

[ColdShowers]

I'm not sure how he tested it, and I must say it looks like it HAS to be the pump - possibly just one tiny component in it, so that it LOOKS like it's working normally in most circumstances.

Do you have any views on whether it is worth getting the pump changed to see if that works? The boiler is 8 - 10 years old; is the pump an expensive part? The boiler has previously been pretty reliable, and I prefer to repair than chuck out and start again, but not if it is already way beyond its expected life.

 

[kevplumb]

get a second morgage and change the pump

 

[ColdShowers]

will do!

 

[ColdShowers]

How did he test it?

The pump had a little notice on it saying how it should be tested. My plumber unscrewed it a bit to expose a little screw, which was wiggling around, and it was making a noise. This was as expected if it was working, as per the Potterton notice on the thing.

Is it possible that this may not pick up certain faults?

 

[giblets]

That test would show that the shaft is turning. It is not unknown for the impeller to break off the shaft (although rare).

 

[baxpoti]

How did he test it?

The pump had a little notice on it saying how it should be tested.

Are you sure that's what is says?

 

[Vic Spanner]

Dont buy the complete pump for the puma. Just get a cheap myson one and just change the head over.

 

[ChrisR]

never known a faulty d.v to cause OH and pilot to go out.

I have. Resolutely stuck in HW position. Pump was finished too, but it made zero difference!

It's usually not hard to tell whether it's the pump or the DV by feeling pipes and seeng how long it takes to get the heat around, but a bit of exerience helps. A surface temperature probe would soon show if there's circulation in the hw circuit while doing ch.

Pumps can get blocked and spin but do nothing.
5 minutes is a difficult time though - there must be some circulation.

At 10 years old the pump is likely to be on a go slow, and the DV could be tiring too. Just 2 of the bits in pumas which have to be changed around that age, along with the fan, and about the second pcb...