Refcomp SRC S screws

[nzchillers]

We have 2 SRC-S-253 screws fitted to a water cooled chiller controlled via a PCoB controller step less control. The compressor are starting loaded even though the unload solenoid is energised in off cycle mode. We have checked and confirmed the operation of the solenoid valves and have even tried to unload the machine by use of a magnet on the un load valve piston. It is estimated both machines have run 20000hrs

We also have a SRC-S-303 which starts unloaded but loads automatically within 20 seconds and also will not unload during running. It is estimated that this machine has also run in excess of 20000hrs

Could this be something as simple as blocked capillaries on the load / unload solenoid pistons or something more serious with leakage's blockages of the slide guides or chambers, i have seen Howdens wear on the slide key and jam

[NoNickName]

Old SRC-S have an inherent fault on the unloader piston. The piston ring seizes within the cylinder, and there is no other possibility than replacing the ring.

[GHAZ]

Hi nzchillers check if the solnoid valve is not broken or stuck ,you can unscrew them while on the compressor and then if its a stepless capacity control check the gasket under the solnoid valve 19, after that you you will have to strip the compressor to see if the slide rod is not broken or the piston seals are damaged,the piston has two seals around it. if you need any capacity control litrature ,let me now and i will email it to you

[RCassist]

Hy Guys,

the SRC-S series compressor have gone through an evolution concerning the unloader piston. Nowadays the problem is solved, but apart from some compressors, which serials are known, suffering from a material problem, the unloader piston problem is a clear signal for a leack in the oil management. High oil carry over due to faulty superheat regulation, mainly in R407C systems, provoques a lousy lubrication. The unloader suffers on the ring gasket on the piston, and/or suffers high frequency virbations on the rod, which brakes.