Setting evaporator suction temp.

[millo007]

Looking for some advice in setting up a TEV and evaporator pressure regulator. The TEV is an alco TISW and the regulator is a Danfoss KVP. The condenser unit is a Marstair mrc30. Running on R404a. Room set up for 5c and humidity set for 35%rh. At the minute suction temp before the regulator is -8c and after is -10c. I'm getting a bit of frosting back to the compressor and I'm considering closing in the TEV a bit. Any advice would be appreciated.

[Tony]

Hello millo007,

So if you want a room temperature of 5°C and you are using R404A the suction pressure should be about 4.4barg (-3.5°C). Is that about what it is? Not according to your figures!!!!!!!

If so, your evaporator exit temperature should be +2.5°C (this would give you 6K superheat), and your figure of -8°C does not compute.

Something sounds very wrong.

[millo007]

Unable to get a superheat reading as there is no gauge connection inside the room. My pressures do seem on the low side at 3.5 bar (-9c) but the suction line is frosting back to the compressor. So opening up the TEV isn't an option. Temperature wise the room is controlling fine at 5c. But the humidity is struggling to maintain 35%. The dehumidifier is working fine so I think I need to get the fridge to control better. Any ideas in regards to the evaporator pressure regulator setting.

[millo007]

After further investigation. Found that the TEV bulb had not even been clamped to the suction pipe. I've managed to get a superheat of 5k before the evaporator pressure regulator. Room seems to have improved holding 5c and maintaining the 35%rh. Time will tell I suppose.