Thermostat does not cycle

Just got the wyze thermostat. When the AC turns on, it just runs and runs for hours and then shuts off for hours. And that causes the temperature to swing wildly in the house. That’s not how my previous thermostat worked or how they are supposed to work. They are supposed to cycle on and off approximately 4 times per hour, running longer or shorter depending on how far from the setpoint. Is Wyze aware of this issue and planning any fix or update?

This is incorrect. You may have a faulty thermostat, or your airflow is terrible, or your system is oversized, or your thermostat location is terrible, but thermostats should run the system until your setpoint is hit, then wait until the threshold temperature is hit and then run again until setpoint is hit. “Cycling” happens as the house cools or warms from other factors, not on any sort of timer.


It’s not a timer, but it’s also not just a setpoint the way you describe.

Just running to the setpoint will overshoot in both directions and cause temperature swings and that is what I am seeing having just switched from a Honeywell to a Wyze.

This is how cycling should work

Go back to school, and re-read the document you are citing. This is to prevent over or short cycling, not to force more cycles to run per hour when the temperature is inside of the set point differential. Also, it’s tiring that you are posting the same information into two different threads.

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Just like in the other thread, the article you quote clearly says exactly the opposite of what you claim it says. Those timers are used to PREVENT the unit from cycling too often.

Being that you misunderstood it so completely, maybe there are other settings that you misunderstood, such as the switching differential and anticipator settings. If you messed with these and any timer settings, maybe set them back to factory defaults and start over.

It’s also tiring that you’re rude, don’t listen to other people, and post the same crap in two different threads.

OK so getting back to the actual issue. Today I gathered some more info. I have the thermostat set to 77. It came on around 5pm. At that time the display said 77. However, 10 min later I checked again and then it said the indoor temp was 79. The AC then ran a LONG time and eventually shut off when the indoor temp reading was 77. I checked a few min later and the indoor temp reading was 75.

There is no massive heat source that was stirred up by the fan, it was a very mild day today, around 74F when this was happening, some sun but not a whole lot. Differential is set to 0.5.

It appears to me the thermostat has a self heating issue. This then causes it to run much longer than necessary (in cooling mode) and the temperature to swing by around 4F instead of 1F.

If anyone else can confirm whether or not they see this same behavior that would be helpful.

Self heating could explain it. Self heating could come from drawing too much current, trying to drive a contactor load, for example, that is larger than the thermostat ratings. In this case, you would need to provide a small pilot relay. Self heating could also come from a poor electrical connection on that cooling output. You could confirm self heating by measuring temperatures. Most often, a thermostat designer would place the temperature sensing element at the very bottom of the thermostat, such that any heating caused by electronics would convect the air upward, away from the element. It actually would benefit the accuracy of the sensing, since it is pulling some new air across the element.

You are right to ask if others are having these problems. If all are having the same problem, it could be a design issue. If some are not having the problem, it is probably your application, and not the design of the thermostat, since the thermostats are all the same.

In my 45 years of working as a control system engineer, these are the most common problems that I have seen causing these symptoms:

  1. Furniture or a door swing are placed in front of the thermostat, blocking normal room air circulation around the thermostat.
  2. Some sort of appliance located below the thermostat which causes local heating.
  3. A beam of sunlight shining through a window onto or near the thermostat.
  4. Thermostat is placed on an outside wall, which does not reflect the inside temperature of the space.

Agreed Bill. Thing is, none of those other things are in play. All I did was replace the honeywell tstat with the wyze tstat, nothing else changed. The honeywell worked and the wyze sorta works but not really - if I want to be comfortable I have to constantly adjust it.

I don’t have an independent thermometer handy but I’ll try to get one and verify this issue. I will say, it doesn’t even take 10 minutes to see the effect. I turn it on and 3 minutes later, the temp reads 2F higher. Turns off and 3 min later the temp magically drops 2F.

You probably need a fairly fast reading air temperature thermometer. An infrared thermometer will take the temperature of the wall which is pretty slow to react.

Make sure that your wiring connection is solid, and check the current and ratings for the cooling. If it was a Honeywell round, those mercury contacts could handle a lot of current without heating. If your thermostat is directly pulling in the compressor contactor or a liquid line solenoid valve, that is a pretty big load.

One other thought - on a Honeywell electric thermostat, the temperature is measured by a bimetal spring. On an electronic thermostat, it is measured by a thermister in an electronic circuit. Is there any chance that the transformer voltage (red wire) is sagging under the load? It would not affect the calibration of a bimetal spring, but might affect an electronic circuit.