Split air-cooled condensing units in very low ambient (cold) operation often add head-pressure control to avoid which problems?
Choices
- (A) Excessive subcooling of slab
- (B) NPSH in fan discharge
- (C) Blower-door failure
- (D) Low head / insufficient condensing pressure, oil return, and liquid flood-back to compressor
Correct answer: (D)
Low head / insufficient condensing pressure, oil return, and liquid flood-back to compressor
Explanation
Head pressure/ fan cycling / VFD condenser fans: maintain stable condensing for expansion device.