Defrost - the defrosting process

In the winter season, the heat pump will regularly have to defrost itself. This is accompanied by (much) steam formation.

Why does a heat pump need to defrost?

As soon as the heat pump starts to produce hot water, the compressor will send an (ice) cold refrigerant to the evaporator. The evaporator can be clearly seen in the photo: the golden-yellow element on the side and back of the heat pump.

When the outside air gets colder, and with sufficient humidity, the proportion of water in the outside air will freeze on the evaporator. For the evaporator to function properly, it must remain ‘open’. The fan can suck the outside air through the open structure of the evaporator, for the benefit of the energy transfer to the refrigerant.

The freezing of the evaporator is clearly visible in the photo above. The more ice builds up, the less energy transfer there is to the refrigerant.

A well-functioning heat pump will start a defrost cycle in time to prevent (too much) freezing. The heat pump then automatically switches from heating to cooling mode. In a properly set up heat pump installation, the heat present in the buffer tank will be used to defrost the evaporator. On average, this cycle will take about 5 to 8 minutes.

Once the defrost cycle has started, water will come out of the heat pump after a few minutes. The video above demonstrates this process well.

“Help, smoke is coming out of my heat pump”

Every winter season we receive disturbing messages from clients. Usually this is their first winter season, and have not experienced the thaw cycle before. “Help, smoke is coming out of my heat pump” or “My heat pump is on fire. I immediately disconnected the power” are messages we receive.

Fortunately, we can immediately reassure the clients.

Powerworld heat pumps have an adjustable defrosting process. The installer can optimize this according to the conditions where the heat pump is located.