What happens first when a heat pump unit switches to heat mode?

When a heat pump unit switches to heat mode, the first step involves energizing the RVR coil through TH-1. This process is crucial because the RVR (Reversing Valve Relay) is responsible for changing the direction of the refrigerant flow, which is essential for the heat pump to function effectively in heating mode. By energizing the RVR coil, the system prompts the reversing valve to switch, allowing the refrigerant to absorb heat from the outside air and transfer it indoors, thereby providing heating.

Gathering information from the overall operation of heat pumps, it's clear that the sequence of activating components must be precise for the system to operate efficiently. The energization of TH-1 plays an integral role, as this thermostat provides the signal needed for the RVR to operate correctly during the transition to heating mode. Understanding this sequence is essential for troubleshooting and maintaining heat pump systems effectively.