Howden Comps on Star pack

[Frosty the Snow]

Hi Guys/Girls,

Is there anybody out there able to give some advice on a Star pack, circ 1990. The pack consists of 2 off Howden WRV 163 compressors and drive motors, economised and thermosyphon oil cooling. Each compressor runs fine on its own but as the lag machine comes in it fails on high discharge pressure. The system is LPR and NH3 is the refrigerant.We thought it might be oil logging and/or a stuck NRV in the discharge but these have been checked and all is fine. We have also checked the oil injection solenoid valves, again all is Ok. Any ideas??
Any advice would be appreciated

Frosty

[Grizzly]

Frosty.
Has it an evaporative condenser?
Or is it air cooled.
Either way note the head pressure increase and try and relate it to your condenser.
IE fan control settings!
Could even be a faulty circulating pump?
Is it on "telstar control"?
Incidentally have you tried air purging
of off the top of the condenser?
Also when did you last do an oil drain?
Grizzly

[nh3wizard]

Clogged spray heads? Purger not working? Just a few thoughts.

[Frosty]

Whats the contract number Mr Snow (I won't call you Frosty, cos thats my name LOL). I work for STS, Star's consultancy division and have access to all the drawings. Sounds like its condenser related (air, scale, shot fins etc - bein a bit vague here cos I don't know what type of condenser it is).

Yours - the real Frosty...

[HallsEngineer]

Have you checked the valve is open?