At 9:45am local time Chiller 1 at End Y went into alarm for "Evaporator Water Flow Lost". When I arrived at the EY chiller yard I observed that neither chiller was running but chilled water pump 1 was continuing to run. I noted the alarm and headed for the mezzanine above the AHU's to asses what the supply and return pressures were nearest the evaporator coil. 

Immediately I read 0 (or what I thought was 0) at the return line. This would generally indicate that there has been enough glycol loss within the system that makeup is necessary via the local tank (though I've never seen it get to 0). Until I read that both supply lines were at an alarming 140psi (normal operating pressures for all 4 supply and return float around 30). I immediately phoned Richard to have him command the chilled water pump 1 off to stop the oversupply of chilled water. For reasons not clear to me the disable command via FMCS Compass was not taken at the pump.

I went back to the chiller yard and observed that 1: the pump had not been disabled and 2: pressures at the pump were at around 100psi (normal operating for the current frequency is about 50).

Following that, I manually threw the pump off at the VFD to prevent further runaway of the system. Between the time of noting 140psi and manually throwing the pump off, the system pressure increased to 160psi.

After a thorough walk-down of the system, I elected not to utilize our designed redundancy in chiller 2 and chilled water pump 2 as I was still unaware what was causing the massive overpressure at all supply and return lines. It was also found that the return line was not actually at 0, but instead had made a full rotation and was pegged on the backside of the needle (all of these need replacement now).

Macdonald-Miller was called on site to help asses what the issue might be. Given that there was recent incursions to flow via R. Schofield the strainer was the primary point of concern. We flushed the strainer briefly at the valve and noted a large amount of debris. after a second flush, much less/next to none was noted. This alleviated the system pressure substantially. 

The exact cause of the fault and huge increase of pressure is still not clear. There are a number of flow switches at the chiller. Bryan with Mac-Miller suspects part of the issue may live there, and we are going to pursue this further during our next maintenance window. Work was also performed at the strainer within the chiller where rubber/latex-esque debris was found. Work on Chiller 1 to continue but for now the system and end station is happy on chiller2/CHWP2. Looking at the FMCS screen shows temp's have normalized as of the writing of this log.

T. Guidry B. Haithcox. R. Thompson C. Soike R. McCarthy