We recently changed a R404A rack (3 pieces of 6 cylinder Bitzer compressors) to R449A without changing the Thermostatic Expansion Valve.
In the past a lot of smaller or bigger cooling furniture and a huge cooling house (-22 degrees Celsius) were fed by the rack. Now there’s only the cooling house left.
The problem: the system is running too low on the LP-side (around 0.25-0.50 bar (~ -32 degrees Celsius). With only one compressor running (we need about 30kW cooling capacity while one comp got 43kW)
Some of the measurements: - LP: 0.35 bar (t0 -33,7) - HP: 15.5 bar (tc 35,5) - Superheat: 16K (too high) - Subcooling: 4K - Discharge: 95,4 - Evap inlet: -19,0 - Evap outlet: -23,5
Looks like a lack of refrigerant in the first place. But I’m actually not sure if it’s this or if it may be another problem. Expansion valve? Too little refrigerant-flow caused by slower refrigerant speed? Too small exp. valve injector?
I already adjusted the superheat on the exp. valve a little, it didn’t make any difference on the LP-side.
Also adding another 40kg refrigerant to the already charged 90kg didn’t make any difference in superheat.
What do you guys think?
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