Baxi80e no dhw

[avant]

No hot water from taps when ch off, diverted overhauled and dhw operates fine when ch on but when heating off pump proving switch will not make , all diaphragms brand new pump proving switch ok when heating on, cheers in advance for any help

 

[Agile]

Sounds like a blockage is preventing the pump flow switch from operating.

Probably something that a boiler engineer would easily diagnose.

Tony

 

[avant]

Thanks for reply, could it be dhw ht/ex as the pump proving switch is fine in ch mode

 

[Agile]

It could well be but you have not given me any clues!

The flow switch on that model is not very critical.

But it could have become critical if the pump pressure is reduced because of a blocked impeller.

If the plate is so badly blocked then I would have expected you would have noticed the poor DHW performance if you use showers.

Perhaps not though if you use baths or have an electric shower instead.

Tony

 

[avant]

I thought pump was ok due to the fact proving switch is fine in ch mode , if impeller was blocked proving switch would not make in ch mode ?

 

[Agile]

What you think may not be what is really happening!

The hydraulic circuits are different on CH and DHW and consequently their resistances are different!

Tony

 

[avant]

New pump head, all is good

 

[plumbingservices]

Wasn`t it already a brand new pump before you replaced the pump head?

 

[snes]

The diaphrams were new, the missing comma made it sound otherwise.

At least, that's my take on it.

 

[avant]

the diverted was overhauled with new diaphragms, I did not suspect the pump as the proving switch was operating fine in ch mode . Obviously the pump performance was not what it should have been

 

[plumbingservices]

How did you find that out?

 

[avant]

Once clearway of plate heat exchanger, diverter and manifold on dhow side proved, the pump was the only thing left.

 

[Agile]

Didn't you check the pump impeller for blockages first and then do the finger test on it?

Tony