Off Load Bypass to prevent -ve Suction Pressure

[AMSYSTEMS]

We are running the system below as a test upgrade for a new design evaporator and we are really happy with the operation. What we do need to do though is to provide a bypass to prevent negative pressures on the suction line but without causing the suction line to freeze up. Due to space limitations we are looking for the simplest solution. We have tried using a receiver as an offloading tank but it was not successful. I had considered using a capillary run from a solenoid valve on a low pressure switch (0psi) and wondered if this was a good option and would the Danfoss Capillary selection software give a sensible option.

We have the systems brazed/soldered and charged by a local refrigeration company but this seems to be a little outside their experience. We have limited knowledge of refrigeration - you may have guessed Any suggestions would be much appreciated.

[a/c.king]

hi
if u maintain your condansing temp at higher temp u will get higher suction pressure, use fan speed controller on HP that will increas your suction pressur with out any paypass.

regards
a/c king

[NoNickName]

What refrigerant is it for a SST of -35°C, and SSH of 52K gives a SDT of 25°C?

[AMSYSTEMS]

Sorry, forgot to say R404A

[murray75]

You can take a pipe from the discharge, connect to a hand valve(or discharge pressure regulator) then a bypass solenoid, then pipe it into the suction line. When it is not cooling, it will be bypassing. With the hand valve you can adjust the bypass pressure to be 5-10psi that way you will not go into a -ve pressure (pump-down).