We recently had an alarm system installed...included in the package is a CT 30 programmable thermostat. The major problem is that the fan tends to run all the time even after the burner or compressor stops. It doesn't just run for a few minutes but for hours. They have replaced the thermostat so it's probably not defective. Is this furnace too old to be controlled by the digital thermostat? It worked with no problems with the old thermostat. Thanks Jeb