507a cold (cool) room suction pressure help

[anonsin]

Hi Guys
Could anyone tell me the best suction pressure for a walk-in-cold room on 507a
I'm running at 40 - 43 psi all looks ok

[Coorsman777]

Sounds low? Whats your design room temp? Evap temp? Evap TD?

[anonsin]

Sounds low? Whats your design room temp? Evap temp? Evap TD?

Thanks Coorsman for your quick reply
Room Temp target 2 - 3 degrees the unit is in a Restaurant kitchen fruit veg meat
Evap temp is -14 c @42psi which i thought was low but the suction felt cold coming back at the compressor ,I was thinking 50 -52 psi, -9 degree Evap giving me around plus 1 degree off the coil

Regards Anonsin

[Jeremy Martin]

Low suction can be caused by a number of things, but we need more info to make the call.

The problem could be in the metering. Probably not since you said the suction gas is cold, but it's a possibility. TXV screen could be clogged, or the TXV could be holding back too much.

Low refrigerant can make suction run low, but I'm assuming you checked the sight glass.

Or, the compressor could be oversized for the application.

That's all I can think of at the moment, anyway. I'm more of an HVAC guy, but been dabbling in refrigeration a bit recently. :) We should have the following information to help in the diagnosis:

Superheat
Head pressure
Compressor model number
Evaporator model number

[question mark]

hi guys
please correct me, is it right in a cool room we should have temp below 4 deg above 1 so that's why i always look ate the suction pressure to be at -5 deg cel for any refrigerant (404,134,22) off course pressures will be different from ***** to *****. even in freezer if the temp has to be -18 i look for -25 suction pressure also i look at the sight glass to be clear as well. what is the proper practice. i have only looked at these thing over the shoulder have't had first hand experience yet.
thanks

[chemi-cool]

If the compressor is not overheated, and temp pulldown time is ok, I wouldn't touch it.
Is there any kind of defrost or it is air defrost?
Do you know the fins spacing?

[Gary]

Hi Guys
Could anyone tell me the best suction pressure for a walk-in-cold room on 507a
I'm running at 40 - 43 psi all looks ok

If the air flows are right and the refrigerant flow is right, then the pressures are right. IOW... it depends.

[Gary]

You might find this helpful:

http://www.refrigeration-engineer.com/forums/showthread.php?19701-Refrigeration-101

[question mark]

thanks a lot mate, its very help full something i should have in my tool bag all the time just to get the bearing straight in hard times. i tend to forget it all the time.