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completed Attachment 144411 the key will cause an issue i have found., the new style has no key nice
completed
finally so i ordered the gasket, rubber and paper., check valve., and misc to complete the job.,when the new c.v. arrivied smooth shaft no key.,when the gasket arrivied i sent it back WRONG ONE., got the right one., now i go in the compressor pull c.v. it comes out with a key., i will post a pic , left camara at shop.,but what was happening was the the shaft w the key was sliding through the housing , binding up., new design has no key slides great.,
finally
Let me know when u get in town
Hey mlkwal1 I'll be down your way the 1st of Dec for a long weekend.
suction gasket all day thanks
there's not much room, but it can be done...just takes skinny fingers to get the gasket areas clean. cperk is funny...2,2 dichloro-1,1,1-trifluoroethane!
Originally Posted by R123 The RTAA's above 130 tons have an oil line solonoid on each compressor. When the compressor shuts down, the UCM de-energizes the oil solonoid before the compressor shuts down to verify that the oil differential switch trips within a certain amount of time. If it doesn't, the UCM calls out an oil safety fault. Thanks, CHCL2CF3,R123
Originally Posted by cperk Does an rtaa 140 have an oil line solenoid or master solenoid? We don't take care of any rtaa's above 125 and they don't. I know the rtha's, rthb's and rthc's oh and d's have them. The RTAA's above 130 tons have an oil line solonoid on each compressor. When the compressor shuts down, the UCM de-energizes the oil solonoid before the compressor shuts down to verify that the oil differential switch trips within a certain amount of time. If it doesn't, the UCM calls out an oil safety fault.
Originally Posted by jemawalton If the oil line solenoid did not shut the chiller should throw a diagnostic that it did not see the oil pressure differential trip the switch on shutdown. Can't remember the specific diagnostic off the top of my head. Does an rtaa 140 have an oil line solenoid or master solenoid? We don't take care of any rtaa's above 125 and they don't. I know the rtha's, rthb's and rthc's oh and d's have them.
Originally Posted by Phisher There should be a distinct sound when the check closes. Put the circuit into a manual pump down. If the check valve is holding then you should maintain a pressure difference between the condenser and evaporator. Have you checked the oil solenod on the oil supply line to make sure it closes when the compressor cuts off? I'm not sure if that can cause the compressor to back spin or not but it might be something to check. Any ideas on that? If the oil line solenoid did not shut the chiller should throw a diagnostic that it did not see the oil pressure differential trip the switch on shutdown. Can't remember the specific diagnostic off the top of my head.
Buy the suction valve gasket. Isoltate the compressor. Unbolt the suction and discharge lines. Slide the compressor on the base rail enough to clear the discharge line. If you cut the line you will still have a hard time putting the coupling on unless you can find a slip coupling.
You should be able do bend it out of the way.
am i wrong? am i wrong to say and do this?.,,, when accessing the discharge end of the compressor to change check valve, piston and rings that the discharge line will need to be unbolted and cut downstream of the discharge line shut off valve,and moved out of the way., that is the only way i see able to have any room to work on one of these areas.,., trane screw rtaa
am i wrong?
and the rest of the story., anyways ., ordered the chcek valve, the following day i called to check in on something else., talked to same guy and he asked me if c valve was on top of compressor., said no ., he faxed over spec sheet., he was going to order me oil system c valve, got right KIT coming., (kit02308) support c valve, o ring washer c valve., retainer c valve seal c valve., and this should do the trick.,,..,
and the rest of the story.,
Better to replace a check valve than a compressor Originally Posted by rover RTAA I assume you have more than one compressor on this chiller, do nothing , let it run , if it blows then you know it was a screwy sound. The primary function of the check valve is to stop the reversal of flow causing the rotors to free wheel in reverse when the gas re-expands after a compressor shutdown in order to prevent damage from the thrust reversal. A second but equeally important function of the check valve is to prevent refrigerant condensing and draining into the compressor during an off cycle. Refrigerant will migrate to the coldest area and in the liquid state is influenced by gravity. In applications like the RTAA where the compressor is below the condenser, if the check valve is not sealing refrigerant could fill the compressor during the off cycle and cause problems ranging from high motor starting current to compressor damage from the hydrostatic forces developed by the screws pumping 100% liquid. My advice is if the check valve is leaking change it out or you will be asking the customer to pay for a compressor replacement in the immediate future.
Better to replace a check valve than a compressor
RTAA I assume you have more than one compressor on this chiller, do nothing , let it run , if it blows then you know it was a screwy sound.
Reading this post I think back to the first of the RTHB chillers we started out here in 94. In the early days of the screws the official company position was "no service work inside the compressor" replacement was the only option. From the first shutdown on this chiller you could here the slap of the check valve but then the screws would rotate backwards for the next 10-12 seconds while the compressor groaned and the chiller vibrated. Obviously a leaking check valve but following much discussion with compressor engineering we were advised the decision was ours to replace the check valve, replace the compressor or leave as it was and run it until the compressor failed. Management made the call and the compressor was left as it was. You know it is now 16 years later, this original untouched compressor has well over 60,000 hrs of service and yes still spins backwards for the same time every shutdown. But I would still agree with the advice in this post, if the check valve is leaking then it should be changed out.
Originally Posted by BergerMech Rob There is a lot of information floating around out there about these mystical screw compressors. Who knows what to believe? Is the discharge check valve there to isolate the refrigerant in the condenser when the machine is off, is it there to prevent reverse rotation, or both? Going backwards
There is a lot of information floating around out there about these mystical screw compressors. Who knows what to believe? Is the discharge check valve there to isolate the refrigerant in the condenser when the machine is off, is it there to prevent reverse rotation, or both?
Originally Posted by graham Ok let me try to expand on what is normal . Chiller running normal conditions , chiller goes into pumpdown compressor shuts off . for about 1 or 2 seconds at the most you will hear a groan or moaning sound followed by a slap as the check valve closes then silence . if this is what you are hearing , no problems . if you are hearing a continuous moan and no slap then yes you have check valve issues . Man we used to have a guy that would go around condeming the 2-3 second back spins and for some reason I would have to do the work. Always pissed me off when the customer was now smart enough to listen when the compressor shut off. I agree that if pressures equalize pretty quickly from back spin on a screw that the check valve should be replaced.
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