Thermostat fan delay function

This needs to be fixed. Guess I’ll pull the G wire for now or put my old stat back on. Super weird though, when it went through the testing phase of setup, the delay was present on heat. Each cycle afterward blowers come on immediately.


I’m with you now, this is a bug. Pulling the G wire off works for the heat cycle, but won’t work for the cooling cycle. (Although there is an easy fix for that - add a jumper at the furnace control board from Y to G). We shouldn’t need to leave wires off and add jumpers for a new thermostat; especially if the problem is a firmware issue.


my wyze thermostat seems to be working ok with the G wire removed. it is mildly warm to the touch near the display. I will borrow the Flir camera from work and take a picture. Self heating can lead to inaccuracy in temperature measuring devices. I may also borrow a NIST traceable temperature measurement device and see how accurate the little beast is in comparison.

another thing that I am not entirely sure is working right is the schedules… I will look at my Home assistant data for the environment temps including the duct temps for my hvac.


You mentioned that you are using the C wire adapter and you have removed the G wire. Are you saying that you removed the G wire at the furnace, or at the thermostat? If you removed it at the thermostat, I’m surprised that it works at all because the G wire from the adapter to the thermostat is common for the Y / G function. If you removed it at the furnace, there will be no impact on the thermostat, especially as regards to the heat produced in the thermostat.

Thanks Ryanmaturi for all your help with this. I look forward to what you find out. If your right that it is self heating for sure it would throw the temperature off.

I removed the g wire at the furnace, I am not suggesting adding or removing wires causes heating. Simply the design and the “smart” aspect having a CPU ram and a full color display.

You should never remove the C wire. If you want to disable fan control on a unit with an adapter, go to the adapter and remove its G wire from the furnace board. Not having a G wire connected may present a problem when you turn on A/C or emergency heat depending on how your furnace is wired.

I was experiencing the same issue with Main Blower Fan immediately turning on during the heating cycle.
I found that my Furnace control board has (G) and (GH) terminals. (G) terminals control the main blower fan, not the smaller draft inducer fan. I searched my furnace model found that the (GH) terminal is for heat only systems. Which is what I have.

After connecting to (GH) and testing, the furnace is now operating the same as the old thermostat.
The burner lights first and once the heat exchanger comes to temp the main blower then turns on. Once temp is reached the burner shuts off and the main blower runs until the the heat exchanger cools.

I am no longer getting the immediate blast of cold air when the thermostat triggers a heating cycle.

Does your furnace have a GH terminal? My furnace is Heat only, NO AC.

I moved the G wire to the GH terminal and the fan cycling started working like it did with the old thermostat.
Hope you get it working.

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I do have the GH but it’s also the blower for my ac so I need it there. So far so good for me just taking out the G wire since I don’t control fan by itself.

Thanks for the info on this. I had a 5 wire Honeywell Wifi thermostat for a AC/Heater forced air system which had the thermostat fail and I also wanted the fan recirc function which Honeywell wanted an upgraded thermostat for another $150 bucks more to enable, so I installed the Wyze. Everything works, except the fan blowing right away before the furnace has heated up. My experience is the same as documented by demiller9 in this thread.

So, this appears to be a “feature” in the Wyze thermostat which needs to be changed in the firmware. Wyze are you listening?

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I installed my new Wyze thermostat last night, same issue. Gas furnace, forced air, no A/C in this climate. Fan comes on blowing cold air until it heats up. Old Honeywell battery powered thermostat fired up the furnace first, then a delay before the fan. Wiring on Wyze thermostat is Rc, G, W1, and C per Wyze instructions. Furnace board only has those 4 terminals plus Y, which isn’t used since I have no cooling. I’m open to suggestions. Maybe try removing the G wire?

Yes, remove the G wire. I believe Wyze needs to fix this, but until they do that works. If you had an A/C, you would need the G to run the blower when the A/C comes on. That’s why I think Wyze needs to release a new firmware.

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The fan coming on immediately during the heat cycle is clearly a flaw in the design and hopefully can be fixed with a software update. Removing the G wire did resolve the immediate problem but now there is no manual fan control. I am surprised that no one from Wyze replied to this forum yet. I really would like Wyze to succeed and I would like to get more of these thermostats for other locations but I am holding back till the function is 100% as advertised.

Aesthetically it is a nice design and the GUI is reasonably easy to navigate.

Also, I notice that the thermostat is warm to the touch on top of the thermostat. I am not sure how this affects the temperature reading yet or if I comfortable with the excessive power draw. Has anyone else been experiencing this?


Thanks for Post @demiller9

I have the same issue and hope this gets fixed at some point. Anything we can do to get attention for issue to Wyze team?

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Can you all clarify a couple things? I thought mine wasn’t getting the delay, but it is operating as expected in my current config.

Those that have immediate fan activation:

  • are you using the C-wire adapter? I have a C wire at the stat.

  • are you using “Auto” on the MODE selection? I am not, but rather have it set to Heat. I suppose that defeats the purpose of the “smart” thermostat but it seems to be operating with a delay.

I have done it in all configurations. Used the c wire adapter before I realized I had a c wire tucked in the wall. I have put fan on/auto/off. G wire on and off. Only thing that allows delay is g wire off and fan auto.

I do not use the C wire adapter because there are 5 wires running between the furnaces and the thermostats. I was using AUTO mode, but have switched to HEAT mode. Now that I have disconnected the G wire (at the thermostat) I have the delay before the fan comes on. Just like my old thermostat.

When the thermostat kicks in heat, it automatically starts the furnace fan. The thermostat is configured for a gas forced air furnace. The furnace fan should not be manually turned on when the call of heat is made.

When a call for heat is made the furnace manages the fan itself, turning it on when the furnace is done pre-heating and turning it off after the residual heat is gone after the heating cycle. Kicking the furnace fan on manually at the beginning of the call causes the fan to run longer, the vent air to take longer to come to temp, and overall higher energy use.

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Same problem here. Hope they fix this or i might have to go back to the old thermostat.