What happens when heat pump goes into defrost mode?
When the heat pump goes into defrost mode, it momentarily reverses operation and goes through the “cooling cycle.” This forces warm air through the outdoor coil, warming it temporarily to remove the frost. It will continue in the defrost mode until the outdoor coil reaches 57 degrees.
When do you need a defrost cycle in a refrigeration system?
In some applications, for example, scheduled defrost periods may not be needed. The normal “off cycle” of the compressor may be adequate to keep the evaporator coil clear of frost. In other applications, a defrost timer may be necessary to help ensure a clear coil by imposing compressor off cycles periodically.
Why does my air conditioner defrost too often?
If the outdoor unit is defrosting too frequently (at intervals of less than 30 minutes) something is wrong. If at the same outdoor temperature that frequent defrost cycle has occurred since original installation, the unit may be under-sized and unable to provide the amount of heat being asked of it.
When does the defrost period end on an evaporator?
Otherwise, the defrost period will end when the defrost timer runs out. After the evaporator is defrosted, the evaporator fans may need to remain off until any residual defrost condensate on the coil surface refreezes.
What does the defrost cycle on a HVAC unit do?
The defrost cycle is your HVAC unit’s automated solution to removing the ice from the heat exchanger. The number of times that your unit will enter the defrost cycle will depend on a variety of factors including the outdoor humidity level, the air temperature, the condition of the heat pump, and the amount of heat that the unit needs to deliver.
How to tell if your heat pump is defrost?
For example, look for signs of a problem with your heat pump defrost cycle. The defrost cycle is activated by the defrost control, which detects ice building up on the evaporator coils and uses the reversing valve to briefly reverse the heating process to melt the ice on the coils.
If the outdoor unit is defrosting too frequently (at intervals of less than 30 minutes) something is wrong. If at the same outdoor temperature that frequent defrost cycle has occurred since original installation, the unit may be under-sized and unable to provide the amount of heat being asked of it.
How often should a refrigeration system be defrosted?
For most applications, two to four defrost cycles per day should be adequate. This may not be enough for unique space usage such as blast coolers and freezers, or applications with high product temperature pull-down loads.