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Thread: first estimate of system charge
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24-12-2008, 08:49 PM #1
first estimate of system charge
Hi all....
I have a pretty basic question that I am getting mixed answers on.... I have researched alot of previous posts, and am still struggling a bit.
I have a air cooled glycol chiller with r134 and a TXV (approx 9 ton capacity). There is a receiver in the system as well. (Documantation on the system MIA, and we cannot seem to get any support from the original manufacturer - and so I have been trying to figure most stuff out, first principles)
OK- the question is what would be a good estimate of proper refrigerant charge? I am getting two different answers looking at past posts.
1) all of Liquid line volume + receiver volume + 30% condenser volume + 70% evaporator volume
OR
2) about 80% of the receiver volume (thus making the receiver big enough to hold 125% of the charge)
A few extra bits of info from the system......
- measured our receiver and it is roughly 1.31 cu ft or big enough to hold approx 105 lbs of r134
- I found an old "startup" sheet and it has "scribbled" on it that 160 lbs r134 used for startup. I don't think I trust this / but it could be right....
- we have been trying to charge the system by subcool/superheat method after replacing the TXV. We are unable to get a clear sight glass all the way up to 160lbs charge, and then compressor starts slugging.
- our system does have head press control via condenser flooding, but I have it all forced through the condenser right now while we try to get the proper charge (I am keeping the pressure up with fan cycling).
........ Any thoughts?!?!
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