Low suction on Trane RTU

[hvacpope]

recently I encounter another voyager with similar set of problems, 2 stages RTU, both evaporators starving, new compressors, superheat way up there with high supcooling, after changing the orifices to TXV's everything went back to normal but the orifices looked clean as whistle, wonder if the crap blocking them was moved while recovering or... ?? who knows what a piss poor design that was.

[acfixit]

Could be an oil logged evaporator.

[hvacpope]

Could be an oil logged evaporator.

oil logged evaporator are kinda of rare in air conditioning, with low compressor ratios, high velocities,temperatures and short piping runs is very unlikely that large quantities of oil would log anywhere besides the total oil charge for a typical RTU isn't much.

[chad_nc]

Did you put a oversized dryer in it or the little ones they come from the factory with, also did you nitrogen purge while brazing in the new orifice header?

[Hook Echo]

Returned today to do a bit more troubleshooting...long story shot, same type of numbers and no conclusions. Pulled blower belt and all circuits looked to be feeding ok. Service manager told me to go ahead and order a txv kit - our parts ordering guy said they didnt have one for this model.
M/N: YCD090C3H0BC
S/N: J41102181F

[hvacpope]

Returned today to do a bit more troubleshooting...long story shot, same type of numbers and no conclusions. Pulled blower belt and all circuits looked to be feeding ok. Service manager told me to go ahead and order a txv kit - our parts ordering guy said they didnt have one for this model.
M/N: YCD090C3H0BC
S/N: J41102181F

Dont buy from Trane their parts guys are on crack. go to United get a 8 tons Sporlan TXV, matching distributor and a roll of tubing for the octopus, if you dont feel like doing it the hard way, Sporlan can make the kit for you, talk to your local sales rep, http://www.sporlanonline.com/unitedstates.htm

[R123]

Returned today to do a bit more troubleshooting...long story shot, same type of numbers and no conclusions. Pulled blower belt and all circuits looked to be feeding ok. Service manager told me to go ahead and order a txv kit - our parts ordering guy said they didnt have one for this model.
M/N: YCD090C3H0BC
S/N: J41102181F

Trane doesn't sell a TXV kit for these units. This is something your going to have to fabricate yourself. Follow Hvacpope's advise and buy the individual parts. And don't let your parts ordering guy at the shop order your parts because this is something that he will screw up unless he's an experienced tech. You'll probably need to go into the supply house yourself and match up these parts.

[929rc51]

Did you weigh in new 22 or the stuff you pulled out? Also have you looked at the charging chart to see where you stand with that?

[Pascone10]

How do you know what size distributer and tube diameter you need for that specific application? Are the distributers rated in capacity? THen just buy the Tube that goes with it?

[hvacpope]

How do you know what size distributer and tube diameter you need for that specific application? Are the distributers rated in capacity? THen just buy the Tube that goes with it?

there are calculations involved in selecting the tubing, distributor and orifice.
basically knowing the unit tonnage and the amount of evaporator circuits will be enough information for the Sporlan rep. to size the rest accordingly.

I've done the calculations manually and somehow my results always differ from my local rep. he uses a sizing software, I always go with what he recommends.
In this particular case I believe is a 8 tons rtu with 9 circuits evap. and the tubing for the octopus 3/16, make sure to braze with safety-silv 56 or 45% and flux, staybrite 8 would also do the trick, I prefer the safety silv56

read this. http://www.jandrewschoen.com/sporlan/20-10_062009.pdf

[kipedwards]

What are the compressor amps doing in all this? Are they close to full load?

[ewwilt]

This compressor had been changed out about year ago because it was shorted to ground...and why was it shorted?? Dont know, didn't get that info.

Possibly an oversized replacement compressor?

Any feedback on one of your original questions? Have you checked the capacity of the new compressor to the size of the system?