Many homes in my area are heated and cooled with a heat pump. I like to test the heating in heat pump mode, being careful not to set the thermostat more than a degree higher than ambient. Then, I try to get emergency/backup heat to come on, either by cranking the stat 10 degrees higher than the room, or by using the manual emergency heat switch.
Usually, the temperature differential in heat pump mode is between 16 and the mid or high 20 degree range. Backup heat seems to be greater than the mid 30s and is generally obvious because it feels and smells like a hair dryer.
Lately, though, a whole bunch of systems I’ve encountered are outputting the same temperature differential in emergency heat as in heat pump mode, and I’ve flagged those as defective.
Is there something wrong in my approach here? Are some of these systems smart enough to lock out emergency heat if the outside temperature is warm enough (say, 40 degrees F) or if the heat pump is working normally? Or are over 60% of systems just incorrectly wired?