Ciat chiller\heatpump question

[safa]

I have a Ciat chiller with 3 40hp compressor with a micro ciat controller, cooling tower and shell and tube condensor. With 3 water lines chilled, condensed and hot.
Yesterday outside airtemp was 29 degrees C. And compressor 3 tripped on high discharge temp.
HP is within limits cooling tower is working fine, compressor 3 has its own seperate condensor. I think the condensor is not getting rid of enough heat for this particular condensor?

Am I on the right track?:D

[jayguy]

sorry, i have never heard of a Ciat, but i'm not from around your parts either.:D heat transfer is heat transfer. what is your discharge temp? water in/out temps? cond temp? what is the high discharge limit trip point?

approach temperature is the difference between leaving water temperature and leaving refrigerant temperature out of your heat exchanger. the lower the temperature difference, the better the heat transfer. check your other refrigerant circuits for a reference. this does not mean that those numbers are correct...only that those approach temps are good enough to keep those circuits online.

you mentioned: "With 3 water lines chilled, condensed and hot." i am not exactly sure what it is that you are talking about here.

lots more info like refrigerant type and the above temps would be helpful.

hope this helps.

[chiller mekanik]

Is this a "direct expansion water heater"?

[chiller mekanik]

It has to be a water heater.

I'm guessing there could be two heat exchangers for the high side?

There has to be a specification you can use to determine the heat transfer ability of the condenser or de - superheater.

Example: the difference between the saturated ref. temp. & the leaving water is what we know as the "approach".

What is the approach of the healthy circuits?

If the approach on the circuit thats failing is higher than the others, that may be a clue that you are having a heat transfer problem.

You could have scale on the tubes, low water flow, etc.

I have never worked on one of these but have become aware of them recently through a friend of mine that is in your area.

If you can't get the help you need here, maybe I can get him to help.

Please let us know how it goes.

[safa]

Chiller uses R22 gas.
Condensor makes hot water for pool and shower. Condensed water goes to cooling tower. Chilled water goes to air handling units. Unit is in a gym.

Will get more temps. for condensor heat exchange today.

Doubt if their is scale build up in condensor tube as we cleaned them recently.
Might be waterflow as we replaced cooling tower recently.

Unit starts showing warning light fro compressor 3 for discharge temp. above 120 degress C.

Unit trips on HP above 2500 kPa.

Thanks for the help guys!

[safa]

Water going into condensor 24 degrees C out 30 degrees. The approach for compressor 3 is 12 degrees C and for 1 and 2, 11 degrees. Compressor 1 has a single refrigerant circuit where compressor 2 and 3 share a circuit.
Compressor 3 circuit has a single heat exchanger/condensor where 1 and 2 share a bigger condensor/heat exchanger.
Unit has been working fine last few days but its only 27 degrees today with 70% humidity.
Temperature of HP gas about 80 degrees on all 3 compressors.
Will check HP, LP, supaheat etc tomorrow.

Thanks

[chiller mekanik]

Depending on the location of the discharge sensor the compressor itself could be overheating due to a broken valve plate or somthing like that.

Have you checked the performance of that compressor with it being the only one on line?

Just another thought.

[safa]

Yep, I measured the actual discharge temps on the seperate circuits, 110 degrees on C3 and 90 degrees on C1 and 2 , I reckon it is definately a burnt valve plate will isolate the compressor next week and open it up and see what can be done.

:rolleyes: