I’ve got a modern (circa 2004) central heat & air system with an odd problem. The temperature reading on the digital control is very inaccurate. I’ve placed a needle thermometer next to the control unit and observed temperature differences (in both directions!) of more than ten degrees F.
Is the actual temperature-sensing hardware on such a system inside the thermostat control, or wired to it from somewhere else? This unit is against an interior wall with no heat-producing equipment behind it, no direct sunlight and no drafts to speak of. The only thing I can guess is that the control unit is just plain ol’ broke, and from prying the thing apart it looks like there’s a standardized wiring color code so I should be able to handle replacing it if that’ll solve my problem. Unless the wiring came with the unit, in which case I’m screwed.
I don’t know the first thing about these newfangled HVAC units. This is the first one I’ve ever lived with and when it works it’s wonderful. I can provide model numbers later if needed. I can tell you from memory that the A/C is a Carrier model, the air handler is from Payne, and the control unit is a Totaline.
Some of the new digital thermostats have an “offset” in the technical menu that allows the stat to display, not what the display what the stat reads, but that reading +/- the offset differential.
IOW, if the stat is innacurate, some stats will have this function to essentially “calibrate” the stat.
Get the make and model of the stat and I’ll let you know if it has this feature.
Lastly, the sensing is at the stat. It’s [very likely] not getting this information from somewhere else.
Thermostat is a Totaline model P474-0100. I’ve downloaded the manual and gone through the setup options. I’ve also calibrated the stat per the instructions (which were conveniently located in a completely different document from the manual) and it doesn’t seem to have any effect. Each time I set it to match the needle thermometer it seems to be running hunky dory for about half an hour, and then I realize I’m freezing my tuchus off because the thermostat thinks it’s seventy degrees. Or the opposite, when it’s hot out.
Thanks for the info so far. Hopefully I’ve just got something misconfigured.
It sounds like you have a bad stat. My personal preference is the VisionPro 8000, which UnaPersson just bought and installed. He posted it in this thread, which included a hyperlink to the stat.