vokera compact 28

[marleyco]

Advise please,
Problem with Vokera compact 28 dhw, hot water unstable. Hot and cold but mostly just lukewarm. I have replaced secondary thermister on hot water side. Tested flow switch, checked venturi, fan and pressure switch. Have also checked min and max modulating pressure along with modulating coil electrical check. I have also checked wires and connections back to p.c.b.
All the above stated in the manual and a phone call to vokera tech who advised me on modulating tests.
The manual is pointing at p.c.b but as you can imagine, I don't want to get this wrong possibly at my expense!
Does anyone agree with the p.c.b or am I missing something.

Any help appreciated

 

[Blake]

Have you checked the filter on the cold inlet has not blocked up as this can cause problems. I take it you have removed the fan and had a really good look at the venturi as that is a common fault on the vokera's

 

[Billy Bob Bob]

and have you ruled out plate heat exchanger? but as said venturies prone to problems

 

[Blake]

I don't think this model has a plate to plate but I could be wrong, I often am

 

[marleyco]

The fan is very clean and so is venturi and hose to pressure switch. I haven't checked inlet filter, just ruled it out as water flow is fine. It's a twin heat exchanger above burner, although I'd imagine the heat exchanger could scale or block but maybe not as prone as the plate type,
Thanks for replies

 

[marleyco]

The fan is very clean and so is venturi and hose to pressure switch. I haven't checked inlet filter, just ruled it out as water flow is fine. It's a twin heat exchanger above burner, although I'd imagine the heat exchanger could scale or block but maybe not as prone as the plate type,
Thanks for replies