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Thread: simple hot gas defrost circuitry
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28-04-2016, 09:12 AM #1
Re: simple hot gas defrost circuitry
To the optimist, the glass is half full. To the pessimist, the glass is half empty.
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28-04-2016, 10:29 AM #2
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Re: simple hot gas defrost circuitry
Better to have the defrost controller close the solenoid and pump let the compressor run till it stops on low pressure. This way you remove the refrigerant from the evaporator and make an ambient defrost faster.
That is basically what a pump down is, closing the liquid supply and let the compressor stop on the low pressure switch, but start again as soon as the LP switch rises when the solenoid opens after a defrost.
on the other hand, you have Pump out, which means that once the compressor stops on the LP switch, you have to manually start the compressor again.-Cheers-
Tycho
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02-05-2016, 08:58 AM #4
Re: simple hot gas defrost circuitry
The "standard" Pump down cycle on many commercial cool room kits are using the method i mentioned above. Two reasons. 1. It's a waste of energy to constantly pump down on every cycle.
( Credit to Chemi for mentioning the position of LLSV.)
2. Mechanical contacts on a LP switch tend to fail after X number of cycles.To the optimist, the glass is half full. To the pessimist, the glass is half empty.