How your air con uses refrigeration to heat your home

Here’s how the heat transfer process works in your reverse cycle ducted or split system air conditioner when you flip it from cooling mode to heating mode:

1. Evaporation (outside unit)

• The cycle starts with the refrigerant being pumped through the outdoor unit’s heat exchanger, its evaporator coil. Despite the cold temperature outside, the refrigerant is colder, allowing it to absorb heat from the outside air.

• As the refrigerant absorbs heat, it evaporates and turns into a gas.

2. Compression (outside unit)

• The refrigerant gas is then compressed by the compressor. Compression increases the temperature of the gas by pushing its molecules closer together, which makes them collide more frequently. This also adds energy to the gas, raising its overall kinetic energy and, consequently, its temperature.

3. Condensation (inside unit)

• The hot, high-pressure gas is pumped into the indoor unit’s heat exchanger, its condenser coil. The coil is a network of tubes made of copper or aluminium, which have high thermal conductivity and therefore quickly absorb heat from the refrigerant gas.

• As the refrigerant travels through the condenser coil, a fan blows over the heated coil, transferring the heat to the surrounding indoor air.

4. Expansion (back to the outside unit)

• After releasing its heat, the high-pressure liquid refrigerant passes through an expansion valve, which controls the flow of refrigerant, reducing its pressure and temperature.

• The cooled liquid refrigerant returns to the evaporator coil in the outside unit, and the cycle repeats, working its magic of turning cool air into warm air.

If you’re thinking about upgrading your home’s heating system, we can help. For some pointers on selecting the appropriate size for the space that needs heating and cooling, check out our Air Conditioner Buying Guide.

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