I have a question about heat pump operation. I know the principles behind them and such, and even did light maintenance on mine a few times over the years. But one thing has me a bit stumped: My heat never seems to get up to the correct temp. The system was replaced in 2019 from a 2005 build. Right now it's 29*F outside. My thermo is set for 72.*F. My heat pump will only get to 67-68 max. If I go to the Thermostat and turn to EMER heat, it will come on up. This, obviously is not a good way of keeping the bill low, As it shuts down the outside unit and uses only the electric strips. But from what I've been able to gather, in conditions like this, there is supposed to be an 'AUX HEAT" indication that comes on that allows the strips to come on, while the outside unit runs as well, and thus, allows the heat pump to catch up to the thermostat setting. The thing is, I never see such an indication, nor is there a setting for it (other than "OFF", "COOL", "HEAT", EMER") on my thermostat. Does my unit just not have such a setting? If I turn on the EMER heat, it will bring up the temp within 20 minutes, then usually stays there for the most part. but once the outside temp drops again, the cycle starts all over. Could this be the thermostat itself (It was the previous units, and is one of those programmable ones, but I only use the hold setting on it)? TEH last time I had the installer look at it, last summer, everything was good.