3 systems, R22 +R417a -- Pressures look okay?

[Good^Man]

Hi there.
Could someone comment on these temperatures and pressures, please. ie if any look poor or if all okay:

There are 3x systems: The first one is R22 and the other two were converted to R417a/MO59. I just wanted to know if they are looking okay as regards these figures.

a) This R22 system seems a bit low on pressures and the FCU temperature differences look a bit shy at 8degC. Am I right that this system is short of gas?

R22 Mitsubishi Electric Twin System
PUH-4YKSA (3Ph)
Condenser on temp: 19 degC, off: 27 degC
Pressure HIGH Side: 12bar
Pressure LOW Side: 2.9bar
Current/Phase: 4 Amps

Cassette #1:
On temp: 19 degC, Off: 10.9 degC
Diff = 8.1 degC (weak?)

Cassette #2:
On temp: 19 degC, Off: 11.1 degC
Diff = 7.9 degC (weak?)
---------------------------------------------------

b) This next system is on R417a. Seems good with FCU temp differences of 12 degC but the pressures seem low-ish.

R417a Mitsubishi Electric Twin System
PUH-4YKSA (3Ph)
Condenser on temp: 22.8 degC, Off: 27 degC
Pressure HIGH Side: 11 bar
Pressure LOW Side: 2.2 bar
Current/Phase: 4 Amps

Cassette #1:
Model: PLH-3GKHB
On temp: 20 degC, Off: 7.8 degC
Diff = 12.2degC (good)

Cassette #2:
On temp: 21 degC, Off: 8.6 degC
Diff = 12.4 degC (good)
--------------------------------------------------

c) This R417a system seems barely okay with FCU temp differences of 10 degC and the pressures look low-ish, I think.

R417a Mitsubishi Electric Single System
Model: PUH-3YKA (3Ph)
Condenser on temp: 20.7 degC, Off: 29 degC
Pressure HIGH Side: 14.7bar
Pressure LOW Side: 1.9bar
Current/Phase: 4 Amps

Cassette:
On temp: 20.8 degC
Off temp: 11.3 degC
Diff = 9.5 degC (okay)

Any Comments please?

[james10]

a, seems to be s.o.g
b,4.3 cond delta T is too low should be around 10c both hp and lp are to loww should be 15-20 barg hp 4-5 barg lp check your evap coil you'll probably find it s frosting over
c, again pressures are too low

[Brian_UK]

Do we get some commission on this purchase deal?

[moondawn]

a) This R22 system seems a bit low on pressures and the FCU temperature differences look a bit shy at 8degC. Am I right that this system is short of gas?

hi there interseted to know but i thought a 8-10 degree differential between air on and air off on the evap is okay??

however it does seem like it is SOG

Also are these systems all non inverter??


cheers lee

[frank]

As with any refrigeration system, be it A/C or fridge, the pressures should be converted to temperature via the comparator and then your decision about whether it is operating correctly should be based on this.

If it is R22 or some other gas, It does not really matter, it is the temperature that is important not the pressure. Superheat or Subcooling are based on temperature not pressure.

We see questions on here about what pressures the system should be running at. If you consider what temperature you want your evaporator to be, then it is an easy task to convert this to pressure for a particular gas which will give you the answer

[monkey spanners]

If you think it is short, weight it out and see, then you can leak test it with ofn if it is.

[Brian_UK]

If you think it is short, weight it out and see, then you can leak test it with ofn if it is.

Might be tricky, his bio states the OP is a buyer not a techy.