We have a Heat Controller single stage geo thermal heat pump. We also have installed some electric heat strips to use as an emergency. We ared using a Honeywell TH6220 Tstat. The system is supposed to lock out the heat pump when you select emergency heat on the tstat, but right now that is not happening and the system continues to call for the heat pump to run even when we selct emergency heat. On the tstat here are connections for "E" Emergency heat relay and for "L" that says "send output when set to emergency heat. We have the emergency heat relay connected to E. The wiring diagram for the heat pump shows a wire going from "send output when set to emergency heat. We have the emergency heat relay connected to E. The wiring diagram for the heat pump shows a wire going from " to the control board on the heat pump. We do not have that wire connected. Do we have to have that connected, and is that what locks out the heat pump when emergency heat is selected.

Different brands of equipment are wired differently. If Heat Controller says "L" should be connected, I would do so.