Hello to all,
Looking for information on water cooled condensing units for medium temp walk in coolers. I have an account that has several constant loss water cooled condensors. As I have just started working on them, all I know of their history is that they have been horribly neglected. (Evap coils plugged so bad you could not see light through them, etc...) I've worked on various water cooled units in the past (water cooled heat pumps, Liebert units, Desert Aire, etc...) but have always been able to get manufacturers instructions regarding appropriate head and suction pressure based on incoming water temp and delta T across the coil. However, on these units, due to their age and lack of tech support from Copeland, I want to be certain that I am diagniosing these units correctly. Any help anyone might be able to offer regarding the following questions would be greatly appreciated.
1) Water is flowing through the condensors even with the compressor off. Is it possible that previous techs tried to compensate for a fouled condenser by opening up the regulating valves? If it is possible to compensate with regulator settings, how would you diagnose a fouled condenser?
2) Is there a rule of thumb regarding approximate head pressure based on inlet water temp and delta T across condenser? (As with the ambient +30 average on air cooled condensers)
3) What would be appropriate sub-cooling and super-heat values for this style of unit?
4) I would like opinions on the merits of using 414 (Hot Shot) versus 404 as a replacement refrigerant on these units. They are R-12 units, several of which are low on charge. I realize that the TXV should be changed but other than that are there any advantages or drawbacks to either refrigerent. (Compressors are Copeland semi-hermedics.) I have both refigerents in the truck and have used both in the past but would appreciate anyone elses opinions.
I will be suggesting an upgrade to exterior air cooled condensing sections but need to keep these dinosaurs running for the interim. Also, any info regarding refrigeration engineering/technical resources would be great. You know, teach a man to fish... Thanks in advance for any help.