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degggendorf t1_iy9q2cc wrote

Reply to comment by MavDrake in For those of you with RI energy... get your nest while it's on sale. by MavDrake

That's what the other person is describing.

If you only have two wires to your thermostat, they are designed to be connected or not connected; that's the only way the system is designed to communicate. The thermostat can't power itself from two disconnected wires, and if it connects them, then it turns the heat on. Enter the Nest Power Connector that only kinda connects the wires...enough to pull a bit of power for the thermostat, but not enough to actually turn on the heat.

Opinions will vary whether that is okay or not, but it is objectively using things in a way they weren't designed, and the majority opinion of HVAC professionals seems to be that it's no bueno.

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MavDrake OP t1_iy9rglr wrote

I realized it after I had posted my response and agree I misunderstood his point.

I had done some review digging its you are correct. Folks with no C wire seem to have partial success with their units however there is a lot of ugly reviews out there.

https://www.amazon.com/Google-Nest-Power-Connector-Accessories/dp/B093TRFQWP?th=1

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degggendorf t1_iy9sh5b wrote

For sure, it seems highly dependent on the exact system whether it likes it or not, in addition to how frequently the heat runs and how much it can charge its battery.

I ended up running new wiring for my two heat-only zones to avoid all the headache. Before that, using a 24VAC wall transformer with wire running up to the thermostat worked well too, but was kinda unsightly.

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