3 ms·

In home systems aren't most of those problems handled by the furnace/ac system itself? Thermostats are pretty dumb.

• CamperBob2 11y ago
  Depends on the hardware. An old-fashioned bimetallic strip/mercury switch thermostat has mechanical hysteresis built in. (Actually, they can have too much lag -- some of them include heating elements to 'accelerate' their response.) Old-school mechanical devices aren't always as dumb as they look. As far as short-cycling the compressor goes, my current HVAC is smart enough to disallow that, but I've lived in older houses where that wasn't the case. You could potentially damage the compressor by wiggling the thermostat back and forth, forcing it to start up against back pressure. Understanding the requirements is really job #1, and first on the list of reasons why HVAC control isn't just a simple "if too cold then turn on heat else turn on A/C" statement. That doesn't mean people shouldn't jump in and try it, of course. It's the best way to learn, if not always the cheapest.