Blueboy
18-09-2010, 08:17 AM
I have been doing some-work with R407a Post conversion - The following information may be useful to anyone converting from R404a to R407A or it may not
R407a is not the same gas as R407c- they operate at different pressures.
R407c Thermostatic expansion valves DO NOT WORK with R407a- They cause the front of the coils to freeze up they cause liquid flood back and and the case will struggle to maintain temperature. EEV's are fine. If you have TEV's Change them to R22 they work just fine and eliminate flood back to the most part
As R407a operates at different pressures to R404a. If you are running an HT/IT pack on R404a and you change to R407a. You must change to suction control pressure. I have found that dropping it from 3.2 BAR (-11C) on R404a to 2.5BAR(-10C) on R407a works form me.
If you have meat serve overs that employ an EPRV and a TEV on R404a- Change the TEV to a R22 ex eq. I used a no3 orifice. I set the super heat to 4C to keep the coil wet and set the EPRV to 3.1 bar. The case works perfectly with 6 defrost per day ( SAT GAS DEFROST ON THIS CASE) before I carried out this work the case always went high temp on the left hand side as you are standing behind it. This problem no longer occurs.
I hope this is useful
R407a is not the same gas as R407c- they operate at different pressures.
R407c Thermostatic expansion valves DO NOT WORK with R407a- They cause the front of the coils to freeze up they cause liquid flood back and and the case will struggle to maintain temperature. EEV's are fine. If you have TEV's Change them to R22 they work just fine and eliminate flood back to the most part
As R407a operates at different pressures to R404a. If you are running an HT/IT pack on R404a and you change to R407a. You must change to suction control pressure. I have found that dropping it from 3.2 BAR (-11C) on R404a to 2.5BAR(-10C) on R407a works form me.
If you have meat serve overs that employ an EPRV and a TEV on R404a- Change the TEV to a R22 ex eq. I used a no3 orifice. I set the super heat to 4C to keep the coil wet and set the EPRV to 3.1 bar. The case works perfectly with 6 defrost per day ( SAT GAS DEFROST ON THIS CASE) before I carried out this work the case always went high temp on the left hand side as you are standing behind it. This problem no longer occurs.
I hope this is useful