Combi Boiler.

whjohnson:

Pressure drop seems strange - partly blocked heat exchanger? If so, I'd expect some kind of overtemp alarm. What is the boiler locking out on? My old Baxi posed a pig of a problem with the what I thought was the pump - seems the pump isn't a pump in the conventional sense, but merely a water circulater which creates no pressure of it's own. A new pump did the trick though. Seems the old one wasn't circulating at the correct rate. Another thing to check might be the DHW and CH temp sensors on the pipework inside the boiler - a straight continuity check will tell you if things aren't right.

I am suspecting a wrongly fitted new diaphragm/needle for the D.H.W. in the diverter valve, or a leak in the heat exchanger that is allowing the sealed heating side water to leak into the D.H.W. system, thus allowing a pressure drop in the heating circuit when a hot tap is opened.


All observations welcomed.


Z.

whjohnson:

Pressure drop seems strange - partly blocked heat exchanger? If so, I'd expect some kind of overtemp alarm. What is the boiler locking out on? My old Baxi posed a pig of a problem with the what I thought was the pump - seems the pump isn't a pump in the conventional sense, but merely a water circulater which creates no pressure of it's own. A new pump did the trick though. Seems the old one wasn't circulating at the correct rate. Another thing to check might be the DHW and CH temp sensors on the pipework inside the boiler - a straight continuity check will tell you if things aren't right.

I am suspecting a wrongly fitted new diaphragm/needle for the D.H.W. in the diverter valve, or a leak in the heat exchanger that is allowing the sealed heating side water to leak into the D.H.W. system, thus allowing a pressure drop in the heating circuit when a hot tap is opened.


All observations welcomed.


Z.