Thermostat fan speed?

Hello, I installed a wyze thermostat last night and immediately noticed a pretty drastic difference in the fan output.
I can still feel heat coming from the vents but with very little force behind it now.

Are these thermostats capable of controlling the fan speed/ using a lower velocity for efficiency, or is it just an on/ off switch?

If the fan is simply running at a lower speed because the house is close to the desired temperature but is still capable of going full speed when needed that would be OK but I wanted to make sure it is set-up and working correctly.

Assuming this it is functioning correctly though then I still have an issue where little to no air is getting to the opposite side of the house since there isn’t enough pressure to get all the way through the ducts now.

Did the thermostat you replaced have multiple speeds? Wyze only has one speed : on. You’d need to have your furnace control the speeds to get different speeds out of the wyze.


Thanks for the reply! It was an old (2009 I’m guessing) white Rogers 1F80-361, the fan switch only had Auto or On [Whole house ventilation] so unless it controlled speed internally I’m assuming it was on or off?

I really don’t know anything about HVAC, but if the fan is controlled by the furnace it couldn’t be something as simple as the thermostat sending a lower voltage slowing it down like DC fan would?

No, most thermostats send the full 24V back to the furnace to activate the various functions. What sort of furnace do you have? Your issue might be caused by the Wyze’s Advanced > fan delay setting, if you change it to “by furnace”, does the fan speed increase? or if it is currently on “by furnace”, try changing it to a 15 second delay.

Oftentimes, the furnace will use different fan speeds for fan only, heat, and cool, so sending signals to it that it does not expect can make the fan run at the wrong speed.

Good idea, I set the 15s delay but it doesn’t seem to have made a difference.

I guess I’m going to have to return this thing, especially since the remote sensors they’re pushing so hard don’t actually exist…

Not sure then. Is it possible you don’t have the fan wire hooked up properly?
Did you need to use the C-adapter when you set up your system?

Yeah it’s weird. I hooked the old thermostat back up though and it’s noticably hotter, and actually doesn’t even turn on very often…

I took the C wire adapter out and I added a real C wire for next time

Thanks again for your help!

1 Like