I live in central Maryland. Does anyone know about how much of the total annual operating time of a heat pump unit does the "auxiliary" (electric) backup heat run. I think the backup switches on when the outside temp is 40 deg F.

We don't get really cold here, but the temp do drop down in the 20s for a number of days/nights in Dec and Jan.

I would venture to guess it is 5% on average.

Thanks.