Because it’s mass produced consumer goods operating on a “below x temperature turn on heat/turn off AC” and “above y temperature turn off heat/turn on AC”. Old ones are just bimetallic strips where you change the trigger position with a slider, and modern ones use commodity grade temperature sensors, and neither is guaranteed to be placed particularly far from the vent.
The sensor is typically on the thermostat. Not at the vents. You would typically place the sensor in a central location in the house. A high quality multi speed motor AC is designed to keep a decently consistent temperature which is a bit more complex than just turn on / turn off. If you’re dropping $15k to $30k on central AC, they aren’t going to cheap out on a poor quality temp sensor.
It’s just not that fine tuned of an instrument. The furnace also runs on intervals so it’s just going to naturally fluctuate a bit. Like with anything “it depends”, but I doubt it’s possible to keep the room within a tenth of a centigrade just with a consumer level thermostat. Maybe in a small room with resistive heating? I’d love to see actual measurements of this.
Thermostats are not exactly calibrated machines unless you spend for a high end model. Put a few next to each other and they might differ 1°C, 2°F. Worse if you take the really cheap stuff.
I have not seen any thermostats in Europe with decimal degrees. But I also don’t think a thermostat is necessarily accurate to that level anyway.
lol you don’t think it’s accurate to a degree Fahrenheit? Why wouldn’t it be?
Because it’s mass produced consumer goods operating on a “below x temperature turn on heat/turn off AC” and “above y temperature turn off heat/turn on AC”. Old ones are just bimetallic strips where you change the trigger position with a slider, and modern ones use commodity grade temperature sensors, and neither is guaranteed to be placed particularly far from the vent.
The sensor is typically on the thermostat. Not at the vents. You would typically place the sensor in a central location in the house. A high quality multi speed motor AC is designed to keep a decently consistent temperature which is a bit more complex than just turn on / turn off. If you’re dropping $15k to $30k on central AC, they aren’t going to cheap out on a poor quality temp sensor.
It’s just not that fine tuned of an instrument. The furnace also runs on intervals so it’s just going to naturally fluctuate a bit. Like with anything “it depends”, but I doubt it’s possible to keep the room within a tenth of a centigrade just with a consumer level thermostat. Maybe in a small room with resistive heating? I’d love to see actual measurements of this.
Thermostats are not exactly calibrated machines unless you spend for a high end model. Put a few next to each other and they might differ 1°C, 2°F. Worse if you take the really cheap stuff.