Weird issue with HW RTD8500

[nyrfan]

If I have it set to say 76, the temp remains constant at 76, great. If I take it down to say 75 while running the temp on the display jumps to 77 almost instantly. If I put if back to 76 the temp on the screen goes instanly back to 76.

Any ideas on this?

Felix

[wyounger]

It's normal and intentional. Honeywell uses a combination of voodoo and psychology in their thermostats, we sometimes say. They work fine, but sometimes people scratch their heads at them. The logic behind it is a challenge to grasp or explain, but here's a shot.

The thermostat measures room temperature in tenths of a degree, but the display can only show whole degrees. If it's about 76.5 inside, it's close to switching the display to 77. If you switch the setpoint to 75 from there, it probably intends to cool two full degrees before it shuts off (from 76.5 to 74.5). While you are asking for 76, though, it's only a half degree away from what you've asked for, and in some cases won't even run the AC until the temperature gets a little closer to 77.

In effect, it's trying to give you a better idea of how far it's got to go before it shuts off again, even though it can only show whole degrees on the thermostat.

I have noticed that Carrier Infinity systems do this too.

[nyrfan]

Thanks for the reply. I just wanted to make sure it was nothing to be concerned about or if I shoud have an HVAC tech come look at.

Thanks,
Felix