Where can I learn about my system.

BIrchy

I am in charge of the mechanical systems where I work, but I really don't have any experience. I've been here about 6 years and am starting to get curious about the chill water pumps and the circulation system.



We have two pumps, Taco FE3010 with 20 hp motors. Each has a valve on both the intake and delivery sides, plus four pressure gauges, two on each side, with one close the pump and one farther away.



I would like to learn how and if I should be adjusting the valves (my boss tends to open the delivery side until he hears what he calls "cavitation" then backs it off. Them valve positions have been marked, but I can't guarantee that the marks indicate the state they were left in after test&balance got through with them, or if my predessor made any changes.



I would also like to know what the function of each of the 4 pressure gauges is.



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My immediate task is to diagnose why the nearest and largest of the 3 air handlers on this system (there are about 20 FCUs on the system also) suddenly seems to be less efficient. We finally found the suction diffussors buried under the pump insulation and cleaned them today. There was a handful of debris in the bottom of the diffusor but the strainer wasn't significantly clogged. I can increase the cooling of this air handler by running both pumps, closing off the branches to the other two air handlers and by closing off the coil bypass balancing valve (to force all water through the coil), but it's still not cooling with a full load of people and lighting like it did in previous years. With the chill water valve wide open, a chill water temp of 42, a return air temp of 71, I'm getting a supply air temp of about 48. On one of the other air handlers (the one furthest from the pumps), I'm getting an SAT almost the same temp as the chill water itself, without cheating on the flow.



I've been lax in nitride testing, but the water doesn't seem to be growing anything.



 Ideas?