Bitzer screw oil migration

[goshen]

Has anybody had a problem of oil migration while working ,of a bitzer screw comp ,
the unit is an air cooled unit, with heat recovery ,using r-22,a danfoss exv.
all pressures are within the norm,250 \65psi water is, ewt-11c,lwt-7c ,sh-7c, the oil seemes to migrate to the air cooled condenser which is off durring heat recovery,as soon as valve to heat recovery closes,hot water reaches set point , all oil returns to comp
i would be happy to hear ideas!
and what can be done to prevent this!

[cool_tech]

HI Goshen
have had problems with bitzer screws running r22 on dx plant it had a trax oil fitted. does this system have an oil seperator on it?

[HVACRsaurus]

Hi Goshen,

I'm not sure about the circuit arrangement, but one suggestion is;

Could small amounts of oil in the discharge line be falling (due to gravity) down the leg of the air cooled condenser & eventually logging in that area?

If so, the repair would be to modify the orientation of the pipe work so the condenser take off is from the top of the discharge line.

[goshen]

Hi
cooltech: the compressor has a built in seperator ,there is no other seperator.
saurus:the entire unit is level ,but what could be happening the valve that shuts the air condenser off is a pressure sensitive valve that opens at a set pressure to reilief the excess refrigerant to the air cooled condenser ,possibly resulting in oil migration without the ability to return .
i am still thinking !!
thx for the answers