Steve Wright
27-04-2006, 06:37 PM
One of our service techs said he had a high pressure (HPC) tripping at 275# (18.9 bar) when the HPC was set for 425# (29.3 bar). The system is R-22.
He said the cause was flood back causing scroll plate separation then the reverse flow of the discharge gas to the compressor caused a hammer effect on the HPC causing it to trip.
This problem occurs specifically as the fan cycle control (FCC) cycles on with with FCC bypassed there is no problem.
Other info: 65# (4.4 bar) suction, 275# head, 2* (1.1*C) superheat, 12* (6.6*C) sub cooling, no rapid equalization as if a pop-off goes off, this is a new 7.5 ton condensing unit on an existing air handler w/TXV, Copeland Compliant Scroll.
I know the 2* (1.1*C) SH too low taking action to rectify that, Replacing the Air Handler like we should have done to start with.
I'm not bitting on the hammering of the HPC, I believe there is some type of restriction in the condenser or its outlet that he is not seeing.
Any ideas or conformations?
Has any one heard of plate separation (compliance) causing a situation like this?
Steve
He said the cause was flood back causing scroll plate separation then the reverse flow of the discharge gas to the compressor caused a hammer effect on the HPC causing it to trip.
This problem occurs specifically as the fan cycle control (FCC) cycles on with with FCC bypassed there is no problem.
Other info: 65# (4.4 bar) suction, 275# head, 2* (1.1*C) superheat, 12* (6.6*C) sub cooling, no rapid equalization as if a pop-off goes off, this is a new 7.5 ton condensing unit on an existing air handler w/TXV, Copeland Compliant Scroll.
I know the 2* (1.1*C) SH too low taking action to rectify that, Replacing the Air Handler like we should have done to start with.
I'm not bitting on the hammering of the HPC, I believe there is some type of restriction in the condenser or its outlet that he is not seeing.
Any ideas or conformations?
Has any one heard of plate separation (compliance) causing a situation like this?
Steve