Some time ago I started a thread about issues I was having with my new Honeywell Vision Pro IAQ thermostat. At the time, the issue was with humidity sensing accuracy and smoothness when in humidify mode (in the winter). Basically, the symptoms were that the reported humidity was quite low (compared to references including a Vision Pro 8000 placed on the same wall), and also tended to stay fixed for a long time and then suddenly "jump".
Due to the issues I was having, my dealer replaced the unit. The new one had the same offset issue, but didn't seem to suffer from the "jumping" problem. Since I could correct for this behavior by adjusting my setpoint, I left things alone.
Now it's summer, and I'm experiencing issues which are disturbingly familiar. The reported humidity continues to be 4-10 points lower that what my two reference sensors (both within 6 inches of the IAQ and both in good agreement with each other) report. More disturbingly, I'm seeing the same kind of sudden jumps, not just in reported humidity but also in reported temperature!
Today, because my humidity was higher than I'd like (around 61% according to the meters I trust), I lowered the dehumidify setpoint on my stat from 50% to 45% to make it kick on (it was reporting 55%). At the time I made this setting change, the stat was reporting a temp of 78F (which is my setpoint), and my references agreed to within 1 degree F.
Roughly two hours later, I noticed that the system had been running a *long* time and that I was feeling quite cold. The IAQ was still reporting 78F. The other devices were reporting 74-75!
I immediately changed my dehumidify setpoint back to 50%. When I hit 'Done' and returned to the main screen, the reported temp on the stat instantly changed to 76F!
These thermostats are supposed to have pretty good accuracy... certainly better than 0.5 degree, right? There's absolutely no way it should jump 2 reported degrees that fast.
[EDIT: After composing the initial version of this message, I went down to look at the thermostat(s) again. My references both read 75, but now the IAQ is back at 78. Arrgghh!]
I'm really not sure what to do, here. This kind of problem is extremely hard for a tech to observe in action -- it's not as if I can make this happen at will. I can confidently predict that my dealer will be... grumpy, if I tell him this thermostat is once again not working.
I'm really hoping that someone here has a close enough relationship with Honeywell that they can help me solve this. I was very happy with my Vision Pro 8000 (the one I'm now using as one of my control references), and I've always had a good impression of Honeywell products but... this is ridiculous. Help!