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I've a spare crystal ball if needed.

You can't even spell Merriam.......Send me that thing so I can teach it some good habits.

Purge soleniods are common leakers. The purge orifice could be plugged up not allowing it to vent.
" Guess I will have to bust out my brand new Meriman mercury manometer!"

In your first statement you said the machine lost 300 lbs of refrigerant. This would indicate the leak is on the high side of the machine where ever the refrigerant was positive. If on the low side then it would have sucked in air only. Was the unit leaked checked while running? Just because it holds a vacuum does not mean it does not leak. Check solenoid valves, gaskets etc.
Does the purge leak purge more when first started and less and less as the machine runs (indicates leak is on the high side) or does it purge all the time indicating the leak is on the low side.
If the purge was loosing the R134a to the chiller then it would not purge at all as the suction temperature would not drop as there is no heat transfer in the purge tank.

Thx for the SB - pretty sure I've covered most of it except #8 - vapor or liquid connections below the liquid level in the chiller condenser - and maybe a leak after the solenoid(s). They were running the condenser water way below design when I walked up on this one ( bypass actuator control line reversed), so it's not hard to believe that they were stacking in the condenser;however, that was corrected before charge was pulled, so connections should be above the liquid level. Havent been on this one since Weds., but I'm told that the contractors pulled a vacuum on the purge which didn't hold, and have declared thier theory about the 134a leaking into the tank to be the cause of the problem. If the PO hasnt been issued for a new purge, I'm gonna pressurize the purge. Gotta be a leak there somewhere.

This may be stating the obvious, but if chiller is truly "leak free", purge is not needed. Having cut my teeth on R-11 units, I've found 123 units to be mystifying. The refrigerant just does not behave the same. Leak testing and purging can both be exasperating. Post does not specify operating mode selected or if purge operation is as frequent with chiller running or idle, items that would tend to steer my diagnosis towards either a leak in the chiller or an ineffective purge unit.

Pull the purge into a vacuum and see if it holds.

If you leak check again check the threads on float of the purge. They tend to leak worse as the purge cylinder cools down. If you are running then hopefully it is in a positive pressure or close to it but if chiller was shut down tank could fill with air rather quickly. I've pulled vacuum alot of times just to have this cause leak check to fail. No, about the third time it happen I decided to pull the float on every rebuild and liberally apply teflon tape to try to resolve.

Originally Posted by ga1279

Guys I know you wanted to close the thread, but Trane did have a service bulletin about this very problem with the purge going into pump-out erroneously. Yes, it does the 18*F and 23*F pump-out start and stop, but it is not caused by a chiller leak. I don't remember what the SB number is. If you were able to achieve that vacuum level it is not chiller related. I am sure any of out profound Trane techs could locate it. Good Luck- GEO

That would be PGRC-SB-2, unexplained purge pumpout was an issue on some pre 1997 purifyer purges. The bulletin does run through some of the causes for pumpout occurring without non-condensables in the chiller, most are covered in the preceding threads.

Also check the pump out pump to make sure it pulls a decent vacuum say 25" min. I have seen cracked diaphrams and dirt or teflon tape in the reed valves. Make sure solenoids seat tight. Sometimes air comes right back in the pump out line.

Floats stick and drain back lines clog with rust and other crud. been there, done that.

Purge purging problems

Guys I know you wanted to close the thread, but Trane did have a service bulletin about this very problem with the purge going into pump-out erroneously. Yes, it does the 18*F and 23*F pump-out start and stop, but it is not caused by a chiller leak. I don't remember what the SB number is. If you were able to achieve that vacuum level it is not chiller related. I am sure any of out profound Trane techs could locate it. Good Luck- GEO

thanks

yeah Klove is probably right - I got my question answered, which was have you guys seen this before. We'll figure it out eventually - thx for the input.

r-123 removed from the centrifuge, place a blank flange instead of the rupture disc and pressure up to 20psig,

This is an open forum, folks, not a DIY site. It's getting a little deep wouldn't you agree?

Originally Posted by sargent york

Make sure drain line is open back to condenser, if liquid can't drain out hot gas will continue to condense filling tank and continue to drop in temperature until temperture sensors turn on pumpout.

If the drain line back to the condenser is valved out, the purge will trip on high liquid level... It's the non condensables that cause the suction temperature to fall below the pump out set point, which is 18 degrees. Simply condensing refrigerant (only) should not cause a pump out... If you can get your hands on a temperature probe, check temperatures in the following locations: Discharge line (around 140 degrees normal), liquid line (around 75 degrees normal), leaving txv (around 0 degrees normal), and place on suction line and watch to ensure that the temperature is actually getting down to 18 degrees when unit pumps out. Also at my company, when we leak check a centrifugal, we use hot water to bring the pressures up. We start going over the machine with a sniffer as soon as we hit 2psi, and we never let the machine get over about 8psi in the process as your burst disk is designed to burst at 15psi... These are my thoughts on it... The above temperatures are quoted out of the IOM for the purifier purge, and are set for ideal environments, 70 degree ambient with 8psi chiller condensing pressure. One other thing, is anyone logging pump out minutes over a 24 hour time frame? When the original leak check was performed, did the technician bypass the pump out orifice in order to allow more non condensables to be evacuated to the canister, quicker? You don't want to leave that on there indefinite, but just temporarily to assist with getting the machine fully operational.

Also, is chiller still on line, and purge still pumping out? It could have some small amount in it that was introduced during the charging process, while changing out drums.

When you say purge started cycling immediately, you do mean the pumpout pump, right? And how quickly is "immediately"? As soon as purge condensing unit started, or when time passed for non-condensibles to collect in purge tank? And is this a Purifier Purge or an Earthwise Purge?

Yeah, that's where we're at. So if the chiller is tight all the way through the purge, and the purge appears to be ok, why is it not picking up enough superheat to keep the pumpout from doing it's thing? What is stopping the heat transfer? Btw - no history on this machine - operator was clearing historical as well as active diagnostics.

You had a vacuum drop test performed, and it included the chiller side of the purge.