I have a York combination system with an oil fired furnace and a heat pump. Everything is working fine but I have a question about how the heat pump and furnace work together.
The thermostat is a 2 stage, when the first stage calls for heat, the heat pump alone comes one. If the room temperature drops another degree or so, the second stage calls for heat also and the furnace then comes on. Here is where my question comes in. When the second stage calls for heat and the furnace comes on, the heat pump compressor still remains on. As the furnace heats up, the heat pump condenser input air is getting hotter and hotter. The heat pump is trying to heat air that has already been heated by the furnace. At some point when the furnace warms up enough, the heat pump does eventually shut off , but it seems that it is shutting off due to a high pressure safety or something and that the line pressure is very high at that point. I imagine I can hear the compressor straining to pump heat into the already heated air and I'm thinking this can't be good for the compressor.
Is it normal for a dual system to be designed so that the heat pump and furnace both are operating at the same time or should the controls be wired to turn the heat pump off immediately when the furnace comes on for second stage?
thanks
Mark