Liebert System 3

[local602]

I have a Liebert System 3 w/glycol that has the refrigeration leak from hell!:mad: I found a leak on the solenoid valve at first.

Charged system again with nitro and left overnight. This morning everything was still holding. Blew off nitro and began evacuating system. Noticed that suction side wouldn't pull down past 24inches of vac, and microns were not low enough to register on gauge yet. I suspected hoses, gauges, or even packing on service valves as a possibilty. After checking, I changed to another set of gauges to be sure and to look for any changes.

I continued checking all the obvious places:service valves, expansion valve, flare nuts for pressure switches, u-bends, distributors,etc. I haven't had any evidence of the condensor barrel leaking internally as I still have a green sight glass as well. Good oil in vac pump, and confirmed vac pump is working ok.

I was finally able to get a little quit in the computer room late today and after another nitro charge, still didn't see or hear anything. I really thought I was going to find a leak on one of the distributors because of the way the factory has them all rubbing against each other. I pulled them all apart so they were not touching and I could check them all.

Being glycol, there isn't much to the circuit, and it is all exposed for the most part. I can't believe I can't find the source of this leak. After going over everything again and tightening up things a bit, micron gauge got down to 740 at the end of day, but didn't stay. There is no evidence of oil anywhere either.

Ran out of time today, but was just wondering if anyone has found any leaks on these guys that I didn't mention above? It might just be that I need to be away from this thing for the weekend!:D

[airworx]

ever thought about using a leak detector.

[hospitalacguy]

It's been awhile since I've worked on one of those units. The only thing I can think off is checking where your freon lines go into the condenser barrel. Maybe check the lip around the compressor itself. Check the welds at the compressor for the stubs for the liquid and suction line. Look at the fins of the Evap and see if there is any sign of oil. You may have a leak in the middle of the coil. One idea would be to put some alot of pressure to the system and coat just about everything with big blue. At least if that doesn't work it'll all be slimy. Hope this helps...

[local602]

ever thought about using a leak detector.

That's how I found the first leak, didn't think I needed to say I used a leak detector, but thanks for your input...:rolleyes:

Believe me the unit is already coated in Big Blue after today hospitalacguy:D

I'm sure I will find it, was just trying to save a little time and get some others input. Isn't that what this place is for?

[The Doctor]

Seen those leak at the WRV bellows and/ or the relief valve, especially if the locality had a major water issue recently(note:Baltimore train tunnel fire a few years back).

And of course, Liebert's Deluxe/3 signature leak, the evaporator inlet at the end of the distributor tube.
Other than that Liebert's are unique, just like everybody else.
They just cost 4 times as much. :eek:

[griz]

If your nitrogen charge held with no pressure drop over night it does not sound like you have a leak. Maybe still have an issue with your insturments. Was your king valves mid seated, liquid line ball valve open. I struggled to find a leak on a liebert this week. Found it on bellows of low pressure switch. I soaped it initially but no bubbles I found it with electronic detector evan after system was almost flat on refrigerant and full of nitrogen. I then pulled the switch off put it upside down withh bellows facing up and soaped, then there was bubbles. My system charge was 21 lbs and there was no sign of any oil.

[william antley]

I've installed a few Liebert systems that had problems similar to yours. I eventually found the leaks by the oil puddles and I'm thinking you might want to check these spots.
There are pressure switches for the compressors mounted on the compressor that have a cap tube run to a gauge port. I found several leaks in the pressure switch where the diaphragm had split or ruptured.
Check all pressure switches, I had done an overniter for the original leak checks and the systems held without even a micron of loss, I even saturated everything then with Big Blu like you've done. Blew the test, evacced to 450 microns and charge to proper subcooling. Had to come back the next week and find the leak, repair and set up as previous and leave. Came back a week later and find the same leak at the remote drycooler for the fan cycling switch, I'm getting very ticked off!
Did the procedure again and haven't had to return for over a year, should be working proper I imagine.
Anyway, check all pressure switches as there have been instances where the diaphragm splits or ruptures, if you're not looking for them , you'll not likely find them.

[chillersandcontrols]

I've also had some hair-pulling phantom leaks on the relief valves. Never showed with detector, but found eventually when conditions were good for a large enough blow-off to leave an oil trail right back to the valve. I concur on the bellows for the OEM pressure switches; they are a onion-skin thick alloy of brass and tend to split and leak intermittently - replace and relocate/remount so they won't vibrate from compressor running. Good Luck chasing that rabbit!

[hands]

Go over all of the pressure switches and pay close attention to the cap tubes. I once had a small leak that was very hard to find and it ended up being the cap tube pressure switch. It had a pin hole in the middle of it, no oil was present and it wasn't rubbing on anything. If you held pressure overnight, you may just be boiling off refrigerant in the oil while evacuating. Try evacuating overnight and see what you have.

Good luck and let us know what you find.

[jbuster]

Been there, done that. Found leak on one unit in the low pressure cutout. Another was due to a head gasket. Yet another at the end of the coil on one of the turns. The worst was on the low press switch. Didn't like using flourescent dye but the cust had heard of it and demanded it. Found the leak and replaced the switch. No problems in 2 1/2 years. Also had a leak on an unloader that was hard to find. Good luck!

[Airmechanical]

Been there, done that. Found leak on one unit in the low pressure cutout. Another was due to a head gasket. Yet another at the end of the coil on one of the turns. The worst was on the low press switch. Didn't like using flourescent dye but the cust had heard of it and demanded it. Found the leak and replaced the switch. No problems in 2 1/2 years. Also had a leak on an unloader that was hard to find. Good luck!

glad you found the leak, not glad you used dye!

did you have customer sign a (made me use dye waiver)



.

[local602]

Thanks for the input fellas, yeh I haven't had any sign of oil anywhere. I have been over the entire unit so far. I had the pressure switches leaking on another Liebert unit, so I disconnected the pressure switches on this one and capped at gauge ports. (Did not make a difference on this one) I am going to pressurize with nitrogen again and give it more time this time. Last time I left it overnight and the pressures dropped 2 pounds. With that being so minimal, I left it longer while I worked on another unit. About 4 hours later and it didn't move. That was when I decided to begin evacuating and the problems started. At this point of course I started thinking it was a problem with hoses, vac pump, etc. After inspecting everything and even switching manifolds, I still couldn't hold a vacuum. It may still be a problem with instruments but going in fresh next week will probably help to.:D

As hands mentioned, that's interesting with the pressure relief. I too have not found a leak there so far, but makes one wonder. I will post my findings this week.

[griz]

If your pressures only dropped 2 lbs overnight that is probably equalization. You might try triple evac (breaking the vacuum with nitrogen twice), Then let your final evac pull down overnight or use two pumps. If your tight and dry you should pull 250 microns after two hours if your equipment is operating properly.

[hands]

If your pressures only dropped 2 lbs overnight that is probably equalization. You might try triple evac (breaking the vacuum with nitrogen twice), Then let your final evac pull down overnight or use two pumps. If your tight and dry you should pull 250 microns after two hours if your equipment is operating properly.

You shouldn't use two vacuum pumps on a system, one pump can actually pull air through the other pump. But triple evacuating is a good idea.

[griz]

You shouldn't use two vacuum pumps on a system, one pump can actually pull air through the other pump. But triple evacuating is a good idea.

Leiberts have a liquid line solanoid valve which isolates the low side from the high side. You use one pump on high side and the other on the low side.

[Airmechanical]

Leiberts have a liquid line solanoid valve which isolates the low side from the high side. You use one pump on high side and the other on the low side.


hey uhh, you dont need 2 pumps :rolleyes:

if you pull from the suction and discharge port at the compressor it will pull the whole system down!

even with the liquid solenoid closed!:eek:


.

[freonguy]

The older deluxe 3s that had Alco HGSV & LLSVs were a bear for leaks at those points.

If you are checking the condenser barrel, open the plug on the end bell and run the head up to 350 or so; check the plug hole for leaking. I have had a few condensers that only leak when up to temperature - ie: running temperature and pressure. In fact, I had a coax once that I removed from an old Trane S/C unit that I figured HAD to be leaking. Submerged it in a tank of cold water and it would not leak @ 400 psi nitrogen. Nearly hairless by this point, I dumped the tank and filled it with hot water - BUBBLE, BUBBLE from the water side!!:p - replaced the condenser - problem gone!!!

I have 24 Deluxe 3s on site that are 15 + years old - still love'em, but they are getting tired - getting more and more water cooled condenser leaks.

Good luck.

[bruiseandy]

Under that piece of crap pipe support on the discharge line between the two compressors maybe. Probably would have found it there but worth a shot.

[local602]

Well after all the aggravation tearing the unit apart, the problem was with my dam vac pump!:mad: I have a brand new j/b premier 7cfm, and I gotta say I am really surprised to say the least! The pump would pull down no problem with manifold shut off, but wouldn't pull down anything more then that!

I actually just decided to switch pumps because we still couldn't find any leaks and it was still driving me crazy. Once switched over, lines pulled down no problem!:eek::rolleyes:

Being a new pump, I never suspected! I have never had a vac pump do this to me, new or old in 18 years. Oh well, first time for everything!

[freonguy]

Local602:

Too bad - everyone out there has at least one tale of woe in similar circumstances - J/B is a great product - you get to rely on the tools you have - they somtimes let you down ( has to be a Viagra joke there somewhere )!

To all the young whippersnappers out there - buy the best tools you can afford and test/calibrate them often. If a gauge or thermometer reading is whacky - take the time to double check it - it is tough to spend the bigger $ when you are getting started, but if you stay with Fluke, Robinair, J/B, Yellow Jacket, Ridgid and Snap-on ( and others, where applicable), you will run into LESS trouble - always remember to double check an electrical meter on a known source before you trust your life with what it tells you - you don't get many chances in life. If nothing else, good tools can make the job go better, save a callback and maybe the hide off your knuckles

This comment might create some debate, but at the end of the day, you DO get what you pay for in most cases.