rtaa trane aircooled screws tripping on low oil flow

[ptrck]

i have an account that i just recently got that has a 200 ton trane rtaa model chiller, and about 1 a week 1 out of the 2 screws will fail on low oil flow.i contacted trane chiller help line and the guy told me to change out the oil differantail switch.this screw requires 47 psi net oil pressure to proof the switch,if this dose not hapen in 20 seconds then it will lock out.i checked oil pressure net and i am showing 62 psi. i checked oil level in the u tube seporator and it is at proper level on all screws. the oil filter is a 5 micron filter and trane said that it should not ever need changing unless the system suffers some type of compressor failure, i am leaning more towards the oil solenoid that allows oil flow back from the oil cooler and lets oil in to the screw. i am wondering if any of you guys out there have had any problems like this with theses trane units, wanted to get some input from you guys before i just start throwing parts at it.thanks pat

[flemsteele]

Check your head pressure , check all of your condenser fans. You will get this trip with high head pressure.

[acjourneyman]

Agree with Flemsteele, high head pressure= increased velocity=higher pressure drop across filter.

[lord of the screws]

This is true high head will cause this trip if all fans are working and cond. is clean you should also make sure both circuits are starting completly unloaded start and watch menue item 27 for that circuit it should start and be around 40% of rla anything higher and fans cannot cycle fast enough to stop from tripping on head this is a common casue for oil and head press. trips and can be caused by numerous other problems if machine has alot of hours on it there is a teflon wear ring on the slide valve piston that wears and discharge press gets past ring and causes high RLA and oil or head trips,alot of info hopefully this will help.

[drivewizard]

Watch your RLA after it starts, if it slowly climbs to around 60% then slams to 90 or 120%(depending on ambient) you may have a lip seal problem. There is a kit for that avail thru Trane Parts Center.
The 100 ton comp are more prone to this problem but have seen it on the smaller one also.
Kit also helps short cycling the comp's on low load conditions. Allows them to unload faster.

[airworx]

i would check the pressure drop across the internal and external oil filters to make sure they not stopped up.
we really need to know subcooling and superheat along with you liquid and suction pressures to see whats happening in the system.
also low head pressure could cause this also.

[drivewizard]

Oil PC opens at 50 psi and shuts down comp. It does not need 47 psi to "proof". The actual press drop across filter should be considerable less than 40 psi when comp is running. If you have 62 psi Delta across the oil filter, start with the filter, make sure your Master Solenoid is opening.

[labrat]

Have this problem going on with a chiller trane screws have no oil pump and rely on the diferential pressure for proper operation 70 lbs saftey set at 40 .Checked actual operating pressures and the sensor had the machine at 220 it was really 160/55 the level was also low in the oil seperator will be changing the sensor and want to load up the circut before adding oil

[mfriar]

i have about 30 of these chillers i work on and would almost definitly say it is a lip seal failure.trane make a repair kit that goes under the load/unload silenoid. refer to the trane service bulletin rtaa-sb-18 also rtaa-sb-4

[carriertechny]

try a carrier next time....

[h2045]

New Member

Registered: Apr 2005
Posts: 9
try a carrier next time....

Carrier what? 30GX piece of CRAP... Stay with the TRANE

John