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Satellite Header- Med Temp Rack

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Discussion starter · #21 ·
Dowadudda said:
your oil failures on this short cycling pump may not be due to it's short cycling. If it were a single unit, then yes. Because it has to run long enough to return oil.

But on a rack your pump is part of an entire oil management system, which delivers the oil through pressure differentials from separator to reservoir, from reservoir to oil regulator, from oil regulator to crankcase.

I am not saying short cycling can't be a problem, but it's low on the list after eliminating many other possibilities and to understand that it's not about actual oil coming to the pump.

A long term short cycling problem could leave you with pitted contacts on your contactor and possibly your contactor is not making on all three legs each time, so your control is looking for oil pressure but it isn't happening cause your single phasing the compressor. That is common and always happens in the dark of night. LOL.

I just want you to distinguish the thought process so you understand. actual lack of oil physically present in the compressor on a rack is not caused by a short cycling compressor generally speaking. I say generally speaking because there are a few things that deserve a longer explanation that indeed could make that happen. It's just down the list.

Most good rack guys will always back up an answer by saying, "there is always the possibility". Because a rack is a unique orchestra of many many parts and sequences. if you always look at racks with a open mind, you will do great.
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Oil problems seem to be the hardest thing for me to figure out and understand on a refrigeration system, especially a rack. I will dig further into why it is tripping. As soon as I figure it out i will post what I found.
 
#23 ·
If that old junked up Alltec controller is too sensitive on the potentiometer dial or not working right, bypass the R.O points and set up the L.P.C's, the Alltec is only an electronic pressure control.

And if all this tweaking of the controls does not stop the short cycling.

Than i suggest that you add a load shed valve in the form of an outlet pressure regulator from the +25 into the +10 This way you keep the +10 header loaded up and reduce the load on the +25 :)

refer to my post a while back about load sheds :)

If cost permits :)
 
#24 ·
270wsm said:
Oil problems seem to be the hardest thing for me to figure out and understand on a refrigeration system, especially a rack. I will dig further into why it is tripping. As soon as I figure it out i will post what I found.
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Is the seperator working?

Given the age of the rack, it may well have an older 'impingement' type seperator. That can be easily IDed by both the inlet and the outlet on top.

If that is the case, pull the float and look at the little screen on the inlet. If it's got a big hole in the bottom, get a new seperator.

If it's a helical, then ignore my advice. :)
 
Discussion starter · #25 ·
jpsmith1cm said:
Is the seperator working?

Given the age of the rack, it may well have an older 'impingement' type seperator. That can be easily IDed by both the inlet and the outlet on top.

If that is the case, pull the float and look at the little screen on the inlet. If it's got a big hole in the bottom, get a new seperator.

If it's a helical, then ignore my advice. :)
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It is the old impingment type. We have been discussing replacing it anyways. The floats are nothing but trouble. Can a different type be put in its place without too much piping change?
 
#26 ·
270wsm said:
It is the old impingment type. We have been discussing replacing it anyways. The floats are nothing but trouble. Can a different type be put in its place without too much piping change?
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Yes.

Cut the discharge line and elbow over into the helical and then fit up.

Took me about an hour, but I'm not a good pipe guy.

The kicker is that, once you crank that rack back up, you have to babysit it for hours to blow down the oil that the new seperator is going to pull out.

I've taken almost 10 gallons of overcharge out of a rack.
 
#28 ·
270wsm said:
What brand do you recommend? Have a link to info on them?
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On older equipment, I generally use Henry.

http://henrytech.turnpages.com/usa/ (hope that link works, look around if it doesn't, the info is there)

On the newer stuff, I have been seeing Temprites. They are a nice unit, but the paper filter element will give you grief if the system is a little older and is dirty.

I also put a Sporlan OF-303 in when doing a separator change-out.
 
#29 ·
I love racks. Each one has its own quirks and special needs. Anyone here old enough to recall the Duo Mates? The low temps Duo Mates were a riot! You needed a truck full of compressor valve plates and gaskets and a year to figure out how to make it work!

Any Duo Mates still out there? The last one I looked after was scrapped when the store met the wrecking ball.
 
#30 ·
I would suggest looking at Temprite for an oil separator. It will do a fine job of both separating and cleaning up the rack. But maybe your not at that point. Seems to be a lot of assumptions going on here. Have you done your homework and and checked out everything to confirm a bad oil separator? We went from talking about load to a bad oil separator due to trouble with oil regs awfully quick.

I just want to point out, not to lose sight of your problem you started the thread out with. And the fact that a short cycling pump on this rack is due to load and settings, and the fact this pump is tripping on an oil safety trip on occasion is possibly another problem.
 
Discussion starter · #31 ·
Dowadudda said:
I would suggest looking at Temprite for an oil separator. It will do a fine job of both separating and cleaning up the rack. But maybe your not at that point. Seems to be a lot of assumptions going on here. Have you done your homework and and checked out everything to confirm a bad oil separator? We went from talking about load to a bad oil separator due to trouble with oil regs awfully quick.

I just want to point out, not to lose sight of your problem you started the thread out with. And the fact that a short cycling pump on this rack is due to load and settings, and the fact this pump is tripping on an oil safety trip on occasion is possibly another problem.
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Ya I did get off topic a bit. Actually, it is a different rack that we are discussing changing the seperator on. Same store, same rack type and age.

The short cycling thing is something I noticed while doing some PM work. It hasn't actually caused any problems yet, but I want to be prepared to get er done, when they do call it in.
 
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