ReplyWhat refrigerant we talking here R-22? Seems your head pressure is low and affecting your oil return.
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Hello I am working on a 35 ton packaged roof top unit with a copeland semi hermetic compressor. I got sent to this site, spoke with building operator he has been resetting the oil failure control ( not good!) I checked over system
-net oil pressure is 50 psig
-suction pressure is 63 psig (loaded)
-head pressure is 150 psig
-compressor amperage is running at RLA
-liquid line sight glass has visible oil bubbling in it
-outlet of the txv, distributor is cold and condensation on feeder tubes
- the compressor does not sound very good, would this be reason for poor oil return
thanks for help
Professional Member*
What refrigerant we talking here R-22? Seems your head pressure is low and affecting your oil return.
Professional Member*
Agreed also the head pressure seems low. You haven't given us much to work with though. How can you be sure it's oil and not vapor or liquid refrigerant? How about superheat, outdoor temp, subcooling, etc?
Professional Member
net oil pressure (if it is calculated accurately) is ok (trip is 9 psid)...but how do you know that it is oil that is bubbling in your liquid line sight glass? i have never seen oil 'bubble' except when heated. i suspect that there is at least 1 other problem.
Last edited by jayguy; 09-25-2012 at 05:32 PM. Reason: cause i wanted to
"Right" is not the same as "Wise".
Don't step on my favorite part of the Constitution just to point out your favorite part.
Just because you can measure it, doesn't mean it is important. Just because you can't measure it, doesn't mean it isn't important.
Professional Member*
What's the oil level in crankcase sight glass?
Professional Member
What makes you think that it is oil bubbling in the liquid sight glass?
Professional Member*
Sight glass could be discolored looking like oil?
It's Hammer Time!
Professional Member*
never seen oil bubble in a sight glass.... oil travels no doubt but seeing it not to likely
it was working.... played with it.... now its broke.... whats the going hourly rate for HVAC repair
Professional Member
Seen something similar,
http://www.youtube.com/watch?v=py_2yOCgKZI
What oil and refrigerant is the system running on?
Professional Member*
^^^^^^^ Click on the video after that one thats called "Refrigeration system full of water" Looks like the guy pulls 6L out of a system he watches the sight glass lower of water LOL
To the OP I am not sure how you know its oil that's doing that? I have never seen or heard of it. You give some more info someone should give you a lead in the right direction.
Professional Member*
Gotta ask, op how do you know its oil.
But just food for thought compressors usually start pumping oil out just prior to destruction.
Give us some more info. And why is the oil failure switch tripping? Bad switch, refrigeration problem?
Regular Guest
Only time I have seen oil droplets hanging on a sightglass ,when the system was or wasn't running was when I started up a large 134a system that had mineral oil in the comps instead of poe.
I questioned this BEFORE startup and was ordered to run with it as it was ordered with the correct oil .
The result was poor or no oil return ,the oil in the sightglass and other issues .
The result ,,,two days with cases of the correct oil , buckets ,and an oil refractometer and plenty of rags until I had it confirmed the oil ratio was acceptable.
Professional Member*
That's really wild, I don't know how I'd react if I saw that for my owns eyes. I'm thinking I'd be getting the recovery pump and tank out.Originally Posted by monkeyspanners
God Speed, Jim. We'll miss you - 2-26-23
Busted wipe ring on one of the pistons.
Professional Member
Its a 40+ year old 90 gallon milk cooling tank, the compressor is about a 1/2hp semihermetic similar to copeland, all the bolts and sump plug have gone very rust from bieng in a dairy for so long as its a packaged system. Was on R12 originally now on R49plus (R437A), it could do with the oil changing to POE but has been working like this for 5 years.
Had a choice of risking breaking the plug off to change the oil or leaving alone, chose to leave it.
Customer has a fix on fail veiw to maintenance...
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