Nest Thermostat with Vaillant VRT 392f controller

[dunder101]

Hello everyone.

We have a Vaillant Ecotec plus 937 combi boiler, combined with a Vaillant VRT 392f RF thermostat controller. We are looking to replace the hard-to-use VRT 392f with Nest third Generation thermostat the next time the boiler is serviced in January.

My question is this: once the Nest Link is wired in and the Nest thermostat connected, can the VRT 392f and its sender unit in the front panel of the boiler be completely removed? Or do they have to remain and perhaps be set to Manual so that the Nest can control the heating?

Thanks in advance.

 

[CBW]

I’m thinking it will need to be removed, as it may block the Nest working correctly. I’m thinking a blanking plate or a timeswitch 150.

 

[dunder101]

Ah - thank you The Novice. So would I be right to assume that, if no controller is installed into the front panel of the ecotec, the heating circuit is always on (unless turned down on the boiler's own temperature knob)?

 

[CBW]

Not necessarily, if there’s a room thermostat controlling it.

 

[dunder101]

Yes indeed ... and the Nest would then fulfill that function (i.e. be the room thermostat)?

 

[CBW]

Yes it would, but with that front panel being connected, it might then block the function room stat.

 

[dunder101]

Just thought I'd come back and close this thread. Nest thermostat installed just before Christmas and works a treat. Installation into the Ecotec 937 very easy. Thanks for all the help and advice.

 

[ianmcd]

where have you connected the grey and black wires from the nest to on your boiler ?

 

[dunder101]

Ah shoot - sorry! The photo inside the boiler was taken *before* the Nest thermostat was wired in. My bad.

The grey and black wires from the Nest are connected to terminals 3 and 4 (in the photo a red loop wire is present, which was removed) - this is the room thermostat connection.

The live, neutral and earth connections to the nest are pigged backed from the live, neutral and earth connections which are to the left of the terminals 3 and 4.

 

[ianmcd]

Ah shoot - sorry! The photo inside the boiler was taken *before* the Nest thermostat was wired in. My bad.

The grey and black wires from the Nest are connected to terminals 3 and 4 (in the photo a red loop wire is present, which was removed) - this is the room thermostat connection.

The live, neutral and earth connections to the nest are pigged backed from the live, neutral and earth connections which are to the left of the terminals 3 and 4.

Ha Ha yes I was wondering as that pic would never work