R407C vs R22

[Abe]

If I were to change to R407C from R22

Would the head pressure be higher for R407 then R22
Would I have to adjust the HP control and the condenser fan cut in switch?

Is a HP condenser cut in at around 200 psig be adequate

[Prof Sporlan]

Would the head pressure be higher for R407 then R22

Yes, in the normal condensing temperature range (70°F - 120°F)

Would I have to adjust the HP control and the condenser fan cut in switch?

A simple yes or no probably isn't possible without additional information.

[frank]

When you say changing to R407 from R22 do you mean as a "drop in"?

This is not possible without an oil change as 407 requires a synthetic oil. If you are talking about an a/c application then yes the compression is normally higher than that of 22 but we have not yet encountered discharge pressures anything like the levels referred to in the press or by word of mouth.

At evaporating temperatures around 5 deg C you can expect a drop in performance of about 5% but as the evaporating temperature drops to sub zero the performance duty drops off rapidly making this refrigerant unsuitable for low temperature applications.

[SteveDixey]

I have also heard that, in comparison to R22, R407C is more likely to condense out in the wet suction return line, and trash the compressor valve plates.

We were alerted to this when a compressor manufacturer refused to supply the contractor installing a 400kw A\C plant with the compressors the contractor originally wanted to use, based on the long suction pipe runs.

Has anyone actually had any experience of this where R22 has been changed to R407C on a big plant?

Steve

[ashraf Bhatti]

R22 gas low pressoure is grater then R407C, and high pressore is hier then R 22 gas. please tell me how much difrance between low & high presoures