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View Full Version : Dunham-Bush Hot Gas By-Pass Problem



Arcturus
09-05-2009, 08:36 PM
I have a Dunham-Bush Model WHSCi 170 horizontal screw chiller using R407c refrigerant. (2 years old)

When first starting in the morning, the chiller goes off on unsafe suction or freeze safety.

What would cause these lock-outs?

The chilled water strainer and secondary loop strainer are new. All flows have been varified and the tubes were cleaned. The air handling coils have been cleaned and new air filters installed.

It has a MCS-8 micro processor. The hot gas by-pass is not activating when unloading causing the chiller to shut down and then restart shortly thereafter. How do I get into the MCS-8 to check the hot gas by-pass setting and make adjustments?
This information is not in the manual.
Do I need software to do this?

I've had three service contractors in the last two weeks and all are stumped.

Can anyone help as Dunham-Bush is no longer

Yuri B.
10-05-2009, 03:20 PM
Little antifreeze in water making evap's surface cover with ice?