Thermostat Call

The sequence begins when the thermostat detects that the indoor temperature needs adjustment (Heating or cooling). If Heating is required, the thermostat signals the heat pump to extract heat from the outdoor air. If cooling is needed, it signals the system to begin removing heat from the indoor air.

Compressor Activation

Once the thermostat signals a need for temperature adjustment, the outdoor unit's compressor kicks in. The compressor's job is to pressurize and prepare the refrigerant to move heat. In heating mode, the refrigerant absorbs heat from the outdoor air, even in colder temperatures. In cooling mode, it removes heat from the indoor air.

Refrigerant Circulation

The refrigerant, a fluid that quickly changes states between liquid and gas, circulates through the system. In heating mode, the refrigerant absorbs heat from the outdoor air and becomes a warm gas. In cooling mode, the refrigerant carries heat away from indoor air and evaporates into a cold gas.

Reversing Valve

One key component distinguishing a split system heat pump from traditional air conditioning systems is the reversing valve. This valve allows the heat pump to reverse its refrigerant flow, switching between heating and cooling modes. When in heating mode, it directs the refrigerant to absorb heat outside and release it indoors. In cooling mode, the process is reversed, allowing the refrigerant to absorb heat from the indoor air and release it outdoors.

Heat Transfer

During the heating cycle, the refrigerant, now a high-pressure gas, travels to the indoor air handler's evaporator coil. As air passes over this coil, the heat from the refrigerant is transferred to the air, warming the indoor space. In cooling mode, the outdoor unit's condenser coil releases heat absorbed from indoors as the refrigerant cools down, converting it back to a liquid state.

Air Distribution

Once the air is heated or cooled, the indoor air handler circulates the conditioned air throughout your home via ducts. The air passes through the blower fan and is distributed evenly to maintain the desired indoor temperature.

Defrost Mode

If the outdoor unit's coils become too cold during Heating, the system will switch to defrost mode. This temporarily reverses the refrigerant flow to warm the coils and melt any frost buildup, ensuring the system continues to operate efficiently.

Auxiliary Heat (If Needed)

During frigid temperatures, the heat pump may struggle to extract sufficient heat from the outside air. In these cases, the system may engage auxiliary heating elements (such as electric resistance coils) to supplement the heat pump's operation and maintain indoor comfort.