Trane RTAA 215// circuit a,b intermittent low oil flow codes 199

[aggiechillertech]

I'm fine with camping on it but just wanted to make sure I have several things to try and narrow it down. I've worked on mainly carrier chillers so this trane is a learning curve. But, personally so far I actually like trane commerical stuff more than the carrier. But they have 1 more RTAA that is working great. I'm not a parts changer so that's what's taking so long when I order parts if need be I want to be able to guarantee to my customer it's fixed. They are patient and understand it's a nasty little gremlin hiding it's just a matter of getting it cornered and terminated.

For diagnostic purposes lets say we put a fan cycling switch on it. Would a bank of 2 fans for each circuit probably be sufficient to rule one way or the other if it's a fan staging problem....?

On the RTAA's what involved with slide valve rebuilding. As far as parts needed and basic procedure. Once the end plate is pulled off of the compressor it's all right there I'm guessing. I have looked everywhere and cannot find a "trane screw rebuild/service manual"

Thanks for all of the help and suggestions it has at lease helped me get a good idea on what's happening to with it.

[stanbyyourword]

It doesnt seem likely both compressors have slide valve issues, though not impossible , sounds like fan staging to me, You need to there with gauges on , checking display transducers, pressures , temps to display ,remember you won`t have much time, A bit off subject but I had a carrier 30gx with oil fault that was driving me crazy , took me a few days to catch processor scrambling the oil pressures , scrolling like a maniac prodialog with gauges on, was a tricky one but got there , as will you good luck

[emcontrols]

2 questions?
a. How did you check oil level in oil collection U bend?
b. Do you think there is a posible restriction in any application that has 25PSIG delta P across any device?

[aggiechillertech]

Used trane's recommended procedure used a refrigerant hose off of the discharge line a sight glass with 1/4 threaded fittings and then hose off of the bottom of oil cooler then moved the sight glass up and down against the oil separator until level could be seen in the sight glass. I dont remember the height measurement but it was taken off of the base rail on the unit support.

The drop across the oil filter's was 25 lbs at 89 degree outside and 268 on the head. As head pressure is lower now that the temp has dropped so has the pressure drop I was averaging about 10-15 lbs at 60 degrees outside last week.

It's starting loaded from time to time more or less based on help from guys here. The problem is making it act up while I'm standing beside it everytime I'm there early in a effort to troubleshoot it the dang thing runs perfect. Let it go overnight below 50 degrees and it may or may not trip the cold weather seems to make this bug surface. When it's 55+ she runs perfect and never acts up we are between cold fronts right now and it's running perfect. No codes when I check it this morning.

[emcontrols]

Used trane's recommended procedure used a refrigerant hose off of the discharge line a sight glass with 1/4 threaded fittings and then hose off of the bottom of oil cooler then moved the sight glass up and down against the oil separator until level could be seen in the sight glass. I dont remember the height measurement but it was taken off of the base rail on the unit support.

Super important to know height? which is proper oil level especially in complicated oil return low ambient conditions. Change oil filter if you havent already. Also, discharge relief valves oil on concrete?

[aggiechillertech]

It was at correct height when I checked it after sitting off overnight. I just dont remember where it was right now. I marked in on the oil separator with a paint marker. It was dead on at tranes recommeneded level.

There are two brand new oil filters in the cabinet but based off of the pressure drop across the filters and other techs on here I just dont think it's worth wasting time on changing them although I'm tempted. After reading on here it seems I may have "Trane first start syndrome" The problem is I have left it off overnight and started it the next morning and she ran perfect. Walk away and she takes a dump go figure.

[emcontrols]

[QUOTE=aggiechillertech;11912052]It was at correct height when I checked it after sitting off overnight. I just dont remember where it was right now. I marked in on the oil separator with a paint marker. It was dead on at tranes recommeneded level.[/QUOTE

10"'s after off cycle is ideal.(More importantly the bottom of U-bend in operation should never float between 4" & 6") 14PSIG diff on oil filter at 200 head, where are you at? As far as condenser fans(Are they factory fan motors? If not we are pretty much pissing in the wind)

[aggiechillertech]

The fans I have replaced since taking over are OE trane. Funny crappy story here I sold the customer on going with OE parts for the obvious reasons. Exactly one month later the upper bearings failed and wiped out the stator taking all of the fuses with it. Yes I had installed new fan blades at the same time the new motors went it just to CYA. Oh well every parts supplier has problems just was kinda hard to explain why I had to replace two already brand new motors a second time.

The rest of the fans are all correct rpm and hp ratings. Although some have been changed and not oe brand they are marathon electric motors they are a good brand.

OK lets assume this thing does have the trane first start symptons as outlined in the trane bulletins. In my mind this explains why after performing all of the slide valve troubleshooting bulletins everything still checks ok when doing procedure later in the day.

I've also tried it first off in the am with no avail too??

[R123]

I glanced back through this thread and, unless I missed it, I didn't see anything about your subcooling. Are you sure this chiller isn't overcharged? If it is, you could be subcooling your saturated condenser temperature sensor which will give the UCM a false lower condenser temp/pressure. Under low load conditions, your refrigerant would stack in the condenser even more causing even higher subcooling. That would cause your fans not to stage up properly. I've seen this a few times before.

[aggiechillertech]

Flame suit on...

When verifying the condenser temp probes I evacuated both circuits and weighed in to the factory charge on the rating plate 225lb per circuit.

When the system is running I'm averaging 13-18 on subcooling. This system barely runs over 5-10 minutes at a stretch before it shuts off so it's real hard to get a figure I'm comfortable with calling accurate.

What method do those of you in cold climates use for verifying subcooling on these RTAA's when it's cold outside. What is tranes recommended method.

Should I be forcing it to 100%load and leave it off for several hours to get the water temp up. When this thing is running it'll take 60 degree water down to 42 and satisfy in about 10-15 minutes with the cold weather.

This unit does not have a remote evap.

[R123]

I'm about an hour and a half southeast of you so I have your same climate. The only way to properly check the subcooling is at full load on that circuit. I know it's a pain in the a*# to get the load up, I've been in your shoes many times. Depending on the application, you can make sure all the ahu's are running and shut the system down for a while if the customer will let you.

I just wanted to throw that out there for you so you have one more thing to check. Make sure you use your liquid pressure, not hot gas pressure, to measure your subcooling. It should be between 11 and 20* at full load with all fans running.

Maybe next time I head up to Aggieland, I'll look you up. My son goes to school there!

[aggiechillertech]

I'll go get a double check on it tomorrow afternoon. I'll jump out the unloader on it and get it to 100% load. Crank the boilers and see if I can get the buildings hot inside and see what it's telling me then.

My gut feeling is telling me it's time to rebuild the slide valve assemblies just based on the first start syndrome I read in one of the trane sb's I found on here. Just want to cover all of the bases as long as I don't wear out my welcome here.

[Dallas Duster]

I'll go get a double check on it tomorrow afternoon. I'll jump out the unloader on it and get it to 100% load. Crank the boilers and see if I can get the buildings hot inside and see what it's telling me then.

My gut feeling is telling me it's time to rebuild the slide valve assemblies just based on the first start syndrome I read in one of the trane sb's I found on here. Just want to cover all of the bases as long as I don't wear out my welcome here.

Well sounds like your way oversized in this milder weather. To me the starting and the stopping it the worst thing for a screw matter of fact any compressor. The fact that you are basically "first starting" these compressors several times a day that you have to cycle the fans the same way and the equilibrium of the machine just can't happen. I'm not saying your slide valves don't need work but both circuits doing the same?

[aggiechillertech]

You are correct this machine is oversized. This summer I had to shut down one circuit to wait for fans that were on order and I was extremely concerned about having to do so. But it held the building complex perfectly with around 48-50 degree water at full load in the middle of august.

I dont know what the engineers had planned on but this thing definitely has the capacity to kick butt and take names when it was averaging 110+ at the hottest part of the summer.

[R123]

The slide valve piston is more susceptible to excessive wear when the compressor runs unloaded all the time.

[aggiechillertech]

It pretty much starts loads to about 40 % unloads then shuts right back off. In hot weather she levels out and runs great. It just can't find a happy spot in the colder weather it's on off on ff on off on off constantly.

[aggiechillertech]

To busy to get by there today,

Anyone have bulletin RTAA-SVB09C-EN handy I just wanted to read through it for a FYI on my part. Thanks Guys

[R123]

To busy to get by there today,

Anyone have bulletin RTAA-SVB09C-EN handy I just wanted to read through it for a FYI on my part. Thanks Guys

Here you go.

[R123]

heres some more good reading.

[aggiechillertech]

You are a mighty man of men good sir appreciate it bunches.

The weather should be warmer on wednesday I'm goin to shut it down and see if I can make it fail the next morning while I have eyeballs on it,