Thermostat for Heat Pump System with Auxiliary Propane Heat

Yesterday I replaced my Honeywell thermostat with a Wyze thermostat. My thermostat uses the following wires: R, C, AUX, E, OB, G, Y, Y2, S1, S2, and jumper between R and RC. My system has 2 speeds for the compressor and air handler, a heat pump for normal heating and propane for heat when the temperature gets below 40 F. When I removed the old thermostat, I was surprised to see 10 wires plus a jumper. By the way - the S1 and S2 wires are for an outside thermometer that tells the heater to switch to propane below 40 F. The Wyze thermostat relies on the internet for that information, and the S1 and S2 wires are not used.

When I opened the box and saw that there was no setup manual, I was concerned and skeptical. I remembered when I had the old thermostat installed, the A/C folks had to come back 2 times before they got it right. But I took my time and was careful and followed the instructions in the App. I double checked all my connections and, as far as I can tell, everything is working well.

Following the installation, I returned the $175 Ecobee thermostat I had purchased from Costco and also was happy that I did not have my A/C guy install a WiFi thermostat at his quoted price of almost $600.

So far I’m happy. If anything changes, I’ll let you know.

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