How do the Cased A-Coils work?Updated a year ago

An Overview of the Benefits of the Cased A-Coil for Furnace Owners

Pioneer's Cased A-Coils can be paired with a furnace as well as the Pioneer YH-series heat pump condenser central split units to create a very suitable setup. Here's a high-level overview of how these components interact and work together:

Furnace and A-Coil Connection
1.    The A-coil, also known as an evaporator coil, is usually installed on top of a gas furnace. In some cases, it might be installed below the furnace. The air that's circulated by the furnace’s fan, also passes over the A-coil.
2.    The A-coil is filled with refrigerant from the heat pump system. When your air conditioning is running, this refrigerant absorbs heat from the air passing over the coil, which cools the air before it's circulated throughout your house.
3.    Since you'll be using a heat pump system, it can also work in reverse to provide heat. In this case, the refrigerant in the A-coil is heated by the outdoor unit and it releases heat to the air passing over the A-coil, which is then distributed by the furnace's blower fan.
Outdoor Condenser Unit Connection
1.    The outdoor condenser unit is connected to the A-coil inside the house via two refrigerant lines. One line carries refrigerant from the outdoor unit to the A-coil (this is the high-pressure line, or "liquid line"), and the other carries refrigerant back to the outdoor unit (this is the low-pressure line, or "suction line").
2.    The outdoor unit has a compressor that pressurizes the refrigerant and a condenser coil that releases heat to the outside air (when the system is cooling) or absorbs heat from the outside air (when the system is heating, in case of a heat pump).
Two-Stage Thermostat Connection
1.    The two-stage thermostat is connected to both the furnace and the heat pump / air conditioning system. The "two stages" refer to the fact that it can control two different levels of heating or cooling. Usually, the first stage is the heat pump or air conditioner, and the second stage is the furnace (for heating purposes).
2.    When you set a desired temperature on the thermostat, it sends a signal to the appropriate system to turn on or off. For example, if you're cooling your home, the thermostat would turn on the air conditioning (first stage). If you are heating your home, the heat pump gets activated first (first stage). If the first stage can't reach the desired temperature on its own, the thermostat would then turn on the furnace to supply additional heat to your home (second stage).
3.    In a heating scenario, the thermostat would first turn on the heat pump if the outdoor temperature is above a certain level (since heat pumps are more efficient in milder weather). If it's too cold outside for the heat pump to work efficiently, certain thermostat types can switch the entire heating function to the furnace instead.

Also, while we've described the A-coil as being installed with the furnace, it's technically part of the heat pump or air conditioning system. The reason it's often installed with the furnace is that the furnace's blower fan is used to circulate air over the A-coil and throughout the house.