jdager

Is there a differance between aux heat and em heat? I have a Honeywell TH4210D that I installed last year. This is the first winter I have lived in the unit and it is also my first time using a heat pump. I have tried to educate myself on the sytem but I'm still somewhat gray in areas. I know the components all work. When I manually switch the unit to em heat I can hear the coils working and the air is significantly warmer at the register. However when I just have it on regular heat I don't feel like the unit ever calls for em heat when the temperature gets below freezing. I was under the impression that it would. The thermostat will occassionally display aux heat, but never em heat. Aux heat is never as warm as em heat but it is warmer then when the the thermostat just displays "heat on". What is the differance? Why doesn't the system ever switch over to em heat automatically? Did I screw up the wiring? It thought I had a 2H/1C. Is there such a thing as 3H/1C...Em heat, aux heat, heat...

Thanks in advance.

jeremydp

Emergency heat and auxilary heat are both your heat strips. When in heat mode thermostat will read auxilary. You have to put it in emergency for it to display emergency. But the control wirings off the stat go to the same place.

kelownadoug

That is all correct. I have lived with a heat pump since 1982. Some winters I never use ER heat (or aux heat for that matter) because it works fine on heat pump. When the temp gets to -10 or so, the heat pump is very inefficient, so it will switch over automatically to aux. It all has to do with the settings programmed. Mine is programmed for a 4 degree drop. If the thermostat is set at 70, and the temp falls below 66, aux heat is automatically applied. I used the setback thermostat for a while. Hated it. If, for instance I set it to setback to 67 for the night, and it kicks in heat just before the morning set forward to 71, the aux would come on. Pros will tell you not to adjust the setbacks so far apart, and that is why.
I am past the life expectancy of my heat pump, so I am looking forward to replacing it with a higher efficiency unit, as well as a new furnace that will move about 4 times the air my old Lennox does.