Wyze Thermostat - Multiple Zones/Systems and Wiring Explained

I’m seeing a bunch of posts about multiple systems and multiple zones, hopefully this will help clear it up a bit. I have over 5 years in the HVAC industry for Residential New Construction and Service/Maintenance.

***NOTE: This does not take into account your current system wiring.
Furnace ONLY - 4 Wires - Typically (R,B,W,G)
Furnace with A/C - 5 Wires - Typically (R,B,G,Y,W)
Air Handler with Heat Pump - 6 Wires - Typically (R,B,G,Y,W,O - Reversing Valve)

There is no industry standard for thermostat wire coloring!
Below is a good example, keep in mind some may have up to 8 wires for additional stages of heat/ac and indoor/outdoor temp sensors.
Red = 24 VAC Power (Required to power the stat)
Blue = 24 VAC Common (Required to power the stat)
Green = Fan
Yellow = A/C
White =

  • Heat
  • Stage 1 Heat
  • Auxillary Heat
  • Emergency Heat

Orange = Reversing Valve (some manufacturers energize in cooling, some in heating)

Multiple Systems (More than 1 indoor/outdoor unit):
You will need 1 thermostat per system. You can mix/match thermostats between the systems as they do not connect to one another. Example: 3 systems (3 separate units indoors/outdoors). Install a Wyze on the first and second systems, install a generic on the third.

1 System w/ Multiple (1, 2, or 3) Zones:
You will need 1 thermostat per zone.
If you have 1 indoor/outdoor unit, with 1 thermostat per floor, you will need 1 Wyze stat per floor.
***You can mix/match thermostats as they are wired independently to the Zone Board.

Multiple Systems w/ Multiple Zones:
Same as the previous example, 1 thermostat per zone per system.

As with anything, all HVAC installations can very. If you have a setup other than what I’ve described, feel free to reply and I will do my best to help.


I have two outdoor units, one going to upper and main floor, gas heat, plus AC,
Second is for the basement , heat pump and ac, all electric.
I installed 1 Wyze on each floor replacing basic programable Honeywell thermostats.
The main and upper floors connect to a Honeywell zone controller, the basement is independent.
So far it Works

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Hi Brian,

I’m a little puzzled by my current Wyze thermostat installation.

This home belongs to my brother and was built here in North Carolina sometime around 2008.

(It’s worth noting, there was originally only a single HVAC system with gas heating and then a second AC compressor was added several years later. Both of those compressors sit outside and have been serviced and work just fine. Each were attached to completely different thermostats of different brands and apparently never cross communicated with one another.)

I thought everything had gone perfectly when I installed the FIRST Wyze thermostat in the upstairs hall a couple of weeks ago. I followed the instructions in the app; everything went very smoothly and seemed to be working just fine.

Last night, I estimated it would only take a few minutes to add the SECOND thermostat to control the downstairs unit, replacing the one that was already there from before, and giving us fully-integrated control of our interior climate,

Man, was I in for a surprise!

While the FIRST Wyze thermostat seemed happy with the wiring as is, the install wizard on the SECOND thermostat told me I needed to add the extra control wire bits to the control board in the Attic. <

I very carefully labeled the wires and followed the instructions but to no avail. When I tested, NEITHER of my smart thermostats was working.

My personal energy zapped, I left everything turned off at the panel, turned up the fire the gas logs downstairs, and started reading more about installations (including your article here) so I can attempt it all again in the morning.

I’m attaching three photos. One is of the wiring before I added the FIRST thermostat which worked just fine. After following the install wizard.

The SECOND is the four wire selection behind the downstairs thermostat, the one the installation told me would require additional control wiring in the attic.

The THIRD is the control board on the HVAC in the attic.

Based on your knowledge and understanding, is this an easy repair for me to accomplish by myself?

It feels as if I’m just missing some simple but fundamental understanding about how the system works and what I should do about the install now.

Eric in Carolina

It appears the discussion board here will only allow me to post one photo at a time right now.

This is the wiring behind the upstairs thermostat the FIRST one I tried that worked just fine with no control wiring extras added.

And here is the wiring behind the downstairs thermostat, the 4-wire mystery that made a mockery of my evening! Haha

It looks the UWP operated without a C wire. I see green for fan, yellow for air, and white for heat. The red wire powers the thermostat.

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Here you have a C wire, so this should have worked fine.

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