This shows an issue as common hvac problems and should become tackled quickly to save energy and prevent significant harm to the equipment.
Heat pumps will naturally ice-up in the winter but will periodically go into a defrost cycle to de-ice the coils. This keeps the unit running efficiently. If the coils are blocked by ice, proper heat transfer between the refrigerant and the outside air cannot occur.
The unit pictured left, was iced-up so badly, it damaged the fan cutting blades, smashed the outdoor coils; leading to the refrigerant to outflow out and destroyed the air compressor - a full reduction.
On a contact for defrost, the reversing valve is energized, switching the program into the air softening mode. That is certainly best - Atmosphere Softening. The outdoor evaporator turns into the condenser but at the same period the outdoor enthusiast shuts off.
This enables the high pressure refrigerant moving through the outdoor coils to obtain extremely warm, burning the glaciers.
At the same, the second stage heat (the back-up heat) is energized to offset or temper the cold air today blowing out the ports. When a sensor or thermostat in the outdoor device gets to a specific temperatures and/or a specific quantity of period will go by, the program will go back again to regular heating system setting.
At this period a cloud of drinking water steam can generally end up being noticed increasing out of the outdoor device and an noisy audio can end up being noticed as the refrigerant reverses path. The whole procedure generally will take between 2 to 10 mins based on circumstances.
Different heat pumps have different ways of identifying when to go into defrost. Some (old versions) make use of mechanised timers in association with a defrost thermostat. If the thermostat is usually cold enough and enough time goes by, the unit will go into the defrost mode, whether it's iced-up or not.
When the thermostat heats up to a certain temperature, defrost is usually terminated. Hopefully at this time, much of the frost has melted off.
Most of the newer gear today uses solid-state control modules with temperature sensors. Even more sophisticated is definitely the Demand Defrost system which makes calculations based on the outside air, the refrigerant temperature in the coil, and run time. This is usually the most efficient way to defrost.
If a heat pump is severely iced-up during winter use, it's possible that it's not defrosting, but there are many other causes.
