DHW not working Baxi Combi 80E

[rjpiggott]

Hi,

I need help please! I have a Baxi combi 80E which has turned problematic with the DHW. The boiler runs CH fine but when a hot tap is turned on it fails to fire. When I've checked, it is not activating the primary flow switch when a call for DHW is made. The primary flow switch works fine with CH though.

I've cleaned everything, flushed the system with X400 twice, replaced the plate heat exchanger, divertor valve and fitted a different (second hand) pump and still no joy. I'm baffled as to why there should be plenty of pressure to activate the primary when running the CH but not the DHW.

Does anyone have any ideas where I should look next?

 

[Rob]

Did you replace the diverter valve complete?

Does it work if you link it out or does it show any signs of bockage?

 

[rjpiggott]

I did replace the complete diverter. Sorry but what do you mean by link it out?

The old diverter doesn't seem to be blocked at all.

 

[Rob]

When you link out the microswitch. What happens?

 

[rjpiggott]

ok, so now I'm having to really coax it to get CH flow on.

In order to get the primary flow switch to work I had to dump water through the PRV so I guess it's looking like the primary heat exchanger may be blocked.

Does this sound likely?

Is there a good cleaning product that I could dose for this?

Otherwise it's a job for my local CORGI man...

 

[rjpiggott]

If I link the switch then it all fires up fine