Vaillant ThermoCompact won't start after system refil

[gas4you]

I my case I'd leave it broken then

 

[gas4you]

Sounds riduclous but when you drained the system did you turn anyt isolating valves off under the boiler including the gas valve, and forgot to turn them back on?

 

[raycampion]

Hi Dave - Was something I checked as soon as we ran into problems. All valves are open

cheers
Ray

 

[raycampion]

Does anyone have the installation guide for this model in electronic format Vaillant Thermocompact VU GB 282/1 E - would be most useful - tks Ray

 

[simond]

ThermoCOMPACT does not need any pressurisation to work. It can be open vent.

However, I think there is a differential pressure switch on the pump circuit that can get stuck, but can't remember the detail.

 

[Gasguru]

Simon, the diff pressure switch appears to function (see previous pic).

However the fact that the on/off indicator light startes flashing is odd. I didin't think this boiler had any diagnostics built in.

 

[simond]

There's something I have in the back of my mind about the function of the diff pressure switch during a call to Vaillant service. It does two things and I remember we had a Vaillant with a seemingly irrational fault which boiled down to the operation of this switch.

I have now read your post, Gasguru, (sorry I missed it) and I wish my memory was better about the operation of it from my discussion with Vaillant tech! Suggest the OP gives them a call.