topic Re: Nest with multiple zone in Nest Thermostats

Nest with multiple zone

fmoacc — Sun, 21 Nov 2021 21:05:21 GMT

I'm looking to replace four older dial thermostats with smart thermostats. We have four areas of zone hydronic heating. I'm probably going to have them installed but I need to make sure I'm getting the right hardware. When doing zone heating can a single Nest Thermostat unit control the zones if you have Nest Temperature Sensors at the other zone locations or does each hub need a full Nest Thermostat? All of the current thermostats have just R and W wires so for most models it seems I'll need to hook the nest power wire (cwire replacement thing) in as well. From what I seems one at the base should be able to support all four mounts? Lots of questions I know I just want to make sure I buy the right equipment.

Re: Nest with multiple zone

AidyBee — Mon, 22 Nov 2021 00:07:28 GMT

Researching like you but my understanding is one nest thermostat and heatsink per zone. Max of 20 zones per home. I think the temperature senders are more about getting a range of readings from various points around a larger zone so the thermostat can make a more informed decision bead on the average across the whole of the zone.

Info in the Nest support sites / manuals suggest that multi zone control you should wire the heatlink to the corresponding zone valve, not the boiler. Nest controls the valve; the valve controls the boiler.

For me, the only thing that isn't clear is now to neatly control HW in a coordinated and coherent way in a multi zone installation. Ideally, I'd like to synchronise / pair the HW channel on all zone nests so that you can adjust a single HW channel from any of the zone thermostats - like a genuinely integrated system. However, I'm not sure that is possible as most people talk about picking a zone to control HW and omit it from all other zone controllers which is a bit naff...

Anyway, hope that helps and happy to be corrected if you find any different information...

Re: Nest with multiple zone

laurentbourg — Mon, 22 Nov 2021 04:58:08 GMT

You cannot control a 4 zone hydronic system with 1 Nest. Each thermostat is connected to a central controller, typically a Taco 4 zone control module which does the valve switching and aquastat control.

So you need one Nest thermostat to replace each dial thermostat. You should not need a C wire, most of the time Nest thermostats are able to “steal” power out of the R line.

Suggest you purchase one Nest learning thermostat and replace one of the dials and then if it all works well you can go ahead and replace all the remaining ones.