baxi potterton oil combi boiler

[bullvine]

Hi to all. I have a baxi potterton oil boiler. when it starts from cold it is fine but when it reaches it's full temperature at 85 to 90 degrees the burner does not cut in when the hot tap is on. the flow switch cuts in and I have measured the voltage which is 240 volts and also the relay switches over but no hot water just cold will come through the tap. other than the flow switch what else will cause the burner not to cut in. many thanks

 

[baxpoti]

I wouldn't expect the burner to cut in at 90°C!

 

[bullvine]

So why do you think there is no hot water is not coming out?

 

[bullvine]

Also is it a possibility that the heat exchanger could be scaled up too much? the reason I ask is the other day I had piping hot water and today just warm water.

 

[baxpoti]

Common faults on this boiler include
Diverter stuck
Pump running slow
Plate heat blocked

You'll need to do some more detective work on where the primary hot water is going.

 

[bullvine]

Ok thanks will do some more detective work.

However this doesn't explain why I have no hot water, surely the burner should cut in if the water is cold!

Many thanks

 

[bullvine]

I have managed to have the plate exchanger taken off and chemically cleaned to good as new. now it is on and the boiler and was fired up. still the same problem, no hot water on the dhw side. the pipe that comes from the exchanger to port B on the diverter valve is piping hot and also port A pipe is hot as well. I manually open the diverter valve and hot water went through to the central heating pipeas it should. my question is. is the diverter valve still passing the hot water which should go to the dhw pipe some where else? any more help would be appreciated