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Hello everyone!
I'm in this project where a 5 compressors Rack system is used to cool 7 rooms, each room with 2 evaporators.
The Rack has beeing working like 3 months but suddenly I noticed that the Superheat at the Compressors inlet is getting very low, some times short periods of time but sometimes considerable periods of time, as low as barely having superheat at all.
Have you ever deal with a situation like this???
Hope you can help!
check the expansion valve bulb for good contact and insulation
How evaporators are defrosted?
Are they full of ice or clean of ice.
Does all fans are operational.
Check individual superheat of all evaporators.
george,
What you consider low superheat? Do you have notice any sign of trouble at the compressors?
Thanks to all!!
Unfortunately there was a broken compressor before we could get there to check the entire system, we found a non operational TXV at one evaporator, it got stuck wide open so liquid refrigerant got to the compressors manifold, apparently the closest compressor to that circuit pipe suctioned the liquid and went out of oil until it broke down.
Do you know why a TXV would ever get stucked after months of correctly operation????
Maybe because a not well cleaned system and debris get in to the spindle and spindle liner...
Could just be the same reason we have service engineers, mechancal items will not last for ever - wear & tearQuote:
Originally Posted by georgedvf
I have been asked by customers in the past to change just the internals(tight wads), but I always try to change the whole valve as the body wears aswell
I think the rack is too young to suffer normal wearing, don't you think?Quote:
Originally Posted by chillerman2006
Yes, I think chillerman2006 missed the 3 months of operation data...:)
We replaced the TXV and run the Rack with the 4 working compressors and seems to be ok. Superheat in compressors manifold is between 25º - 29ºF.
Yep..guilty as charged... lept before i lookedQuote:
Originally Posted by Sandro Baptista
I guess then we can only assume a fabrication defect???
I think the superheat is a little high unless you have an heat exchanger liquid-suction and/or an high DT on the evaporators or lack of feed on the evaporators.Quote:
Originally Posted by georgedvf
I think that one compressor out off order and some pressure drop and heat gain on long pipe runs could give such numbers (12-15K) without heat exchanger and at full load.Quote:
Originally Posted by Sandro Baptista
Okay, but it will be high non useful superheat and/or high pressure drop. Let see: If if you have an DT=8K » useful superheat about 6 K. Maybe the TEV should be better regulated to performance the plant.Quote:
Originally Posted by nike123
Yes, I agree with that, I meant it was ok because no liquid refrigerant was coming back to the compressors so I was reliefed. We will get the new compressor and after installation we will adjust all TEV's superheat.