Comparison of R22 vs 407C on water chiller

Hi, I'm mainly familiar with R22 in water chillers. I understand 407C is similar in terms of running pressures, temperatures etc. I'm looking at a water cooled chiller and I'm getting 18 - 19 bar head pressure and 3.5 - 3.8 bar suction at 18 degC ambient. I would assume if this was 22 that the condenser is fouled or we have a problem with the dry air cooler on the roof but I just want to confirm my assumption that the head pressure should be no higher than about 12 - 14bar. Also looking at some of the other threads on 407c it seems that at higher condensing temps it may run into trouble cooling, any thoughts? Its a shell and tube HX by the way. Chiller is about 10 years old.
Fintan

Fintan

12 to 14 would be right if you had eev's fitted, for tev's i'd be running at 16 to 18b, this is assuming leaving water temps of about 6c. Pressures for 407 and 22 are similar except evaporating at zero 22 would be 4b and 407 would be slightly higher.

Post more info on the chiller operating conditions, lwt,ewt ambient, air off etc....

al

Thanks AL
One system
TEVs are fitted, screw compressors (one per circuit X2). Remote DX condenser on 407C.
3.5 bar suction
19Bar discharge
ambient 18degC
Evap inlet water temp 10degC
Evap outliet water temp 8deg C
Sight glass clear
50amps at 420v (high side) expected 400
FL

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