View Full Version : oil return problem hussmann protocol

03-12-2015, 02:56 AM
having problems with a hussmann protocol low temp rack with air cooled condenser. turbashed has no oil in it the oil reservoir has no oil also.
Receiver level 40 percent this condenser is the new krack coils with microchannel panel system.
At first thought there might be a leak but the levels are good in receiver.
Receiver on roof with blanket and heater.
I dont want to add oil but compressors locking out temporarily and alarming but then auto resetting on traxx oil system.
checked pressure across turbashed had a 5 psi drop.

cant get oil to come back to rack raised setpoint for condenser for about 2 hrs but didnt get any oil back.
what procedure do you use to get the oil back to protocol? setpoint for condenser is 190 psi.

Glenn Moore
04-12-2015, 01:55 PM
Hi Tools
What's a turbashed never heard that expression before?

04-12-2015, 02:47 PM
Its the oil separator , dont know if its a brand or model name.

04-12-2015, 07:06 PM
Oil separator should return over 80% of oil leaving compressor.

You did not state refrigerant and evaporating temp.??
Is your evaporator below or over the rack?
Microchannel condenser has nothing to do with it.
Have a look at the evaporator coil, on parts where it holds oil, there is no cooling so no ice on the pipes.

Is it flooded evaporator?

I would start with lowering superheat by opening the TXV, increase head pressure and see how it goes.

5% psi pressure drop is high, I always prefer serviceable separators.

Glenn Moore
05-12-2015, 01:10 PM
Hi Tools
Try putting the system through a couple of manual defrosts as most likely the oil is logging in the evaporators. Check the suction superheat at the compressors is ok as scrolls can throw a lot of oil around the system if s/h to high or to low or if they have liquid injection control on the compressors this can often over inject and cause oil carry over

05-12-2015, 09:15 PM
Just a thought, if the pipe temperature is hot after the turbashed valve then check the oil inlet temps at each compressor. It is possible that one of your traxoils is passing. If so valve it off and see if your oil comes back.