Trane RTU pluged orifice - HVAC-Talk: Heating, Air & Refrigeration Discussion

jtricor · #1 07-30-2010, 08:48 AM

We have 20 of these RTUs, alot with the same isues pluged orifice, what is the best way of cleaning, some of these units have bad compressors in them so system will be opened up to change out comp.
M: TCD301K40ACA

Painful Chafe · #2 07-30-2010, 11:58 AM

Are these the ones with several orifices pinched into the lines on the header on the evaporator coil.?One orifice for each circuit in the evaporator. Or is it just one?

jtricor · #3 07-30-2010, 01:46 PM

yes they are

jtricor · #4 07-30-2010, 01:49 PM

Its a header system there must be 6-10 of these orifices in there

Painful Chafe · #5 07-30-2010, 04:44 PM

I have seen this caused by a filter drier core coming apart. Also, excesive moisture can cause it, but it would need to be a lot of moisture. You can try to blow the evap out backwards. I would cut into the liquid and the suction pipe just before the headers going into the evap to get as much nitrogen flowing through the evap as possible. Blast it out with 300psi of nitrogen. Then toss a half a can of Rx11 in it(get the kit if you don't have one) and blast it out with nitrogen again. Hold a clean rag an inch or so away at the liquid line that you cut and see if you get anything out. Unfortunately if you get pieces of drier core out its almost impossible to get it all out. You may be looking at new evaporator coils on all of them. Experiment with one first and see what you get. Let me know what you find. I'm a bit curious.

yellowirenut · #6 07-30-2010, 04:51 PM

replacing that orifice manifold sucks....plane and simple it sucks. Expect it to take most of a day, plus a half hour of crying over your lunch.

lynn comstock · #7 07-30-2010, 05:02 PM

The suggestion of Post #5 (Painful Chafe) may work. Since you have multiple units with this problem, I would learn as much as possible before doing any remedial work.

Recover the gas
Test for acid
Remove the drier, cut it open and examine it
Remove any problem orifices and examine them to see the actual obstruction
Depending on what I saw as an obstruction I would plan a remedy for the problem.
The remedy would include a new HH Sporlan drier and a liquid line shutoff ball valve ahead of the drier.
The remedy would probably include a suction line drier.

Never forget to make a profit. If you can't...Walk away.

BergerMech Rob · #8 07-30-2010, 05:40 PM

Clean the coils.

Fix the leaks.

Don't go back with the short orifice assembly, instead, go with the TXV upgrade.

bdclark · #9 07-30-2010, 07:21 PM

Have you performed any superheat tests on these units? I would bet that your headers have been freezing up. Are there any crankcase heaters installed? Jumping off of a cliff here, but I think you might find somewhere in the ballpark of 25º-30º of superheat on a hot day, and the answer you are looking for is thermal expansion valves. I don't know everything about these Voyagers, although I do work for Trane and have done a boatload of factory warranty work on them. I could be wrong, but the nameplate on these units will tell the tale. Manufactured dates between 1996 and 2002 would suggest that I may just be correct. Just my two cents.

You may also want to consider replacing the LL driers with 30 cu. in. driers and adding 1.5 lbs of refrigerant to each circuit.

Painful Chafe · #10 07-30-2010, 10:32 PM

Quote:

Originally Posted by bdclark

Have you performed any superheat tests on these units? I would bet that your headers have been freezing up. Are there any crankcase heaters installed? Jumping off of a cliff here, but I think you might find somewhere in the ballpark of 25º-30º of superheat on a hot day, and the answer you are looking for is thermal expansion valves. I don't know everything about these Voyagers, although I do work for Trane and have done a boatload of factory warranty work on them. I could be wrong, but the nameplate on these units will tell the tale. Manufactured dates between 1996 and 2002 would suggest that I may just be correct. Just my two cents.

You may also want to consider replacing the LL driers with 30 cu. in. driers and adding 1.5 lbs of refrigerant to each circuit.

Are you saying to install a TEV instead of the orifices. I'm not sure how you would remove the orifices. They are crimped in the line. Maybe someone knows if there is some type of conversion kit. New manifold(which would be pretty difficult to put it, I imagine) and a TEV. I've done Trane orifice to TEV conversion but never on the crimped in multiple orifice coils.

FLTUDITECH · #11 07-30-2010, 11:19 PM

I just repaired a 10 ton Carrier with the same setup. Orifices are pinched in line with the evaporator and were plugged and freezing up. The local Johnstone branch had a fix that worked great. It entailed cutting off the entire manifold and brazing in a distributor assembly that they have. They mix and match 4,6,7 and 8 tube distributors and orifices to match the tonnage of the unit. Today was the first time I installed one and it worked great and the unit set up perfectly. Drop me a line and Ill see if I can send you some pictures. Haven't been on here in a while and forgot how to post.

Steve

Painful Chafe · #12 07-31-2010, 04:10 AM

Quote:

Originally Posted by FLTUDITECH

I just repaired a 10 ton Carrier with the same setup. Orifices are pinched in line with the evaporator and were plugged and freezing up. The local Johnstone branch had a fix that worked great. It entailed cutting off the entire manifold and brazing in a distributor assembly that they have. They mix and match 4,6,7 and 8 tube distributors and orifices to match the tonnage of the unit. Today was the first time I installed one and it worked great and the unit set up perfectly. Drop me a line and Ill see if I can send you some pictures. Haven't been on here in a while and forgot how to post.

Steve

Interesting. I'm trying to imagine what it looks like. Does it look like what you cut out and match right up? Pictures would be great if you are going to be at the job again. You can just upload pictures at a site like photobucket.com and post the "img code" here.

FLTUDITECH · #13 07-31-2010, 08:49 AM

I have pictures but they didnt turn out the best. Try to picture that entire header gone. Basically I cut off the entire header just after the orifice with a pair of side cutters. Then opened the cut pipe just enough so that I could slide my capillary tube in and then pinched it back down. Then you just pipe into the distribution tube with your liquid line.