Do i need to pump down???

[chillyblue]

Hi all

i am making a system to de-humidify air.
The system consists of cond unit, evap, internal equalized tev, drier, sight glass, hot gas bypass valve to maintain close control on suction temperature.
The system has a duty of around 900watts running on R404a maintain a evap temperature of 0deg C.
Pipe runs are very short (only about 1mtr)

Do i need to fit a llsv for pump down when the humidity has reached it's set point??? and the comp cycle's off??

If i don't use pump down will the evap fill with liquid emptying the condenser/reciever, threatening the comp on re start.

CB

[WINJA]

you make get bad floodback on start up so a pump down system with llsv would be ideal , you could put an accumulator on but depending if a cch is fitted it may be a pointless as it wont over come the crankcase filling with liquid during extended off cycles anyway

[sunil4seasons]

A crank case heater will help your compressor to have a smooth restart when u start ur system after longtime

[Brian_UK]

Also, compare the quantity of refrigerant that your system will contain with the maximum charge that the compressor was designed for.

If you are below that amount then things should be OK but include a CCH anyway.

[Magoo]

ChillyB,
if you are concerded about short pipe runs and floodback install LLSV and cycle it with compressor, not necessarily a pump down cycle.
magoo

[smilies]

Also, compare the quantity of refrigerant that your system will contain with the maximum charge that the compressor was designed for.

Can you elaborate on this statement? Maybe I'm losing something in the translation. I know of total system charge or receiver/ condenser charge but not compressor charge. Are you maybe talking about compressor CFH or CFM?