Hot Gas vs Compressor defrost
The base model comes with a programmable compressor defrost cycle. ie:
- The compressor is turned off for a period of time to warm the evaporator plate, and thus melt any ice.
- This will lift the internal chamber air temp by about 2.5° – 3.0° for a period of about 6-10 mins.
The hot gas defrost is also programmable (if installed on the unit) to flush the evaporator plate with hot gas.
- This can be set to run for 30 seconds (usual) to a max of 2 mins. At 30 secs the internal air temp raises about 1 degree
The hot gas defrost is not normally required under Pharmacy / Medical Centre setups, as the temperature band (2° – 8°) allows enough leeway for a rise of 3°. i.e. A set point of 3.5° will increase to about 6.5° under compressor defrost, which is still within the temperature range.
A lab fridge may however be set with a temperature band of 2° – 4° (as we do for meat in New Zealand). Under this setting, a compressor defrost will lift the internal temperature outside that band – thus cause alarms etc. Therefore the hot gas option is required to perform a defrost while still keeping within the parameters.
This is one of the main questions that needs to be asked when selling to non-vaccine customers.