Considering Nest in new build apartment

[pcdj]

We've recently moved in to a new build apartment which I understand has communal heating for the entire building, controlled by a Digistat +2 thermostat installed near the front door.

Before we go ahead with the purchase I've been researching the necessary changes which will be required to install a Nest 2nd gen. The Digistat, as far as I can see, is powered by 240V and the Nest only takes 12V, so a direct swap over in removing the Digistat and replacing with the Nest control isn't possible.

Does anyone know if the installation will therefore require the Heat Link to be installed somewhere else (electrical cupboard, I guess) and we'll have to remove the Digistat and fill in the hole in the wall/clean up the cables where it resided? Looking at the instructions, the Nest thermostat could then be placed anywhere in the apartment - powered by its own 12V power supply (presumably communicating with the Heat Link over WiFi?)

We're looking for as seamless a replacement as possible that won't require too much filling of voids/repainting, but it seems like that might be the case here?

 

[bernardgreen]

communal heating for the entire building

Will you need to also interface your new thermostat to the control system of the communal heating system ?

 

[pcdj]

Will you need to also interface your new thermostat to the control system of the communal heating system ?

The existing thermostat just provides basic on/off functionality, so it's fairly dumb (if that's what you mean by the question?)

 

[OwainDIYer]

Simple way is to install the Heatlink over the existing Digistat location, and then use the separate Nest base/power supply where required.

However you may find the Digistat is wired back to a zone valve / heat meter and you will be able to put the Heatlink there and repurpose the cable to the hallway to use to power the Nest, as the instructions assume.

 

[bernardgreen]

It might be that if there is a single heat source for several apartments then the single heat source may fire up only when one or more of the apartments is calling for heat. Hence the demand for heat from your thermostat may go to both your heating system and the central heat source. Changing your thermostat may involve that connection to the central control system

 

[pcdj]

Simple way is to install the Heatlink over the existing Digistat location, and then use the separate Nest base/power supply where required.

However you may find the Digistat is wired back to a zone valve / heat meter and you will be able to put the Heatlink there and repurpose the cable to the hallway to use to power the Nest, as the instructions assume.

Thanks, that tallies with what I had in mind (regarding both your suggestions).

My question regarding the repurposing would be how to handle the 240V-to-12V conversion? I don't think the existing wall plate has much room for transformers and such so I think I'm stuck.

 

[pcdj]

It might be that if there is a single heat source for several apartments then the single heat source may fire up only when one or more of the apartments is calling for heat. Hence the demand for heat from your thermostat may go to both your heating system and the central heat source. Changing your thermostat may involve that connection to the central control system

I see. Would I be able to identify if this is such a system before calling out a heating engineer? As I stated above, we're trying to work out if this is actually cost effective before purchasing the device and getting someone in to fit it - if it's plug and play (with little-to-no modifications to the existing decor), then we'll likely go ahead.

 

[Dan Robinson]

It might be that if there is a single heat source for several apartments then the single heat source may fire up only when one or more of the apartments is calling for heat. Hence the demand for heat from your thermostat may go to both your heating system and the central heat source. Changing your thermostat may involve that connection to the central control system

Give it up.

 

[Dan Robinson]

I see. Would I be able to identify if this is such a system before calling out a heating engineer? As I stated above, we're trying to work out if this is actually cost effective before purchasing the device and getting someone in to fit it - if it's plug and play (with little-to-no modifications to the existing decor), then we'll likely go ahead.

Have installed several smart stats from various manufacturers and it is dead simple. Certainly no different to any other system. Half an hour for a professional start to finish.

 

[pcdj]

Have installed several smart stats from various manufacturers and it is dead simple. Certainly no different to any other system. Half an hour for a professional start to finish.

Yes, I don't dispute that. Let me be clearer: A 'leccy will fit the system but not fix the gaping holes in the wall where the Digistat has been removed and/or wiring has been rerouted/modified. That'll require additional cost/effort to clean up, either on my part as a DIY or getting someone else in to repaint, etc.

The latter's essentially what I'm weighing up here, as if it was a simple remove-the-digistat and replace-with-nest that wouldn't be necessary.

 

[Dan Robinson]

A 'leccy will fit the system

Hhhmmm male sure he's familiar with Heating electrics.

gaping holes in the wall where the Digistat has been removed

There shouldn't be.

 

[pcdj]

Hhhmmm male sure he's familiar with Heating electrics.

Sorry, heating engineer.

There shouldn't be.

If I remove the Digistat entirely, place the Heat Link in the electric cupboard, and place the Nest thermostat in the living room, I'm definitely going to have wires and a hole in the wall where the Digistat previously was!

I'd prefer not to have the Heat Link on the wall where the Digistat was as it serves no purpose.

And so far no one's offered a solution to the 240V/12V problem, hence my thinking on the placement above.

 

[Dan Robinson]

And so far no one's offered a solution to the 240V/12V problem

You repurpose the wires.

 

[bernardgreen]

Give it up.

How does the central heat source know when to fire up and then how much heat to produce ? Or does it fire continuously and use return temperature to determine if more heat is needed to be provided and hence alter its modulation level.

Come on Dan.... give the OP the benefit of the wealth of knowledge and experience you have at your finger tips.

 

[Dan Robinson]

There's no need to. One simply reads the instructions and transpose the wires for the spdt relay from the Digistat.