Water Cooled Units Tripping On High Pressure

rookietech2006

Hi people !
Here is a novice contractor looking for some advice. I am servicing a 80-ton water cooled system consisting of 15 5-ton Trane Axiom units. The owners use them mainly on weekends. The thing is that when they fire the system up on saturday`s afternoons, cooling tower and pumps running all normal, most of the units trip on the high pressure control. I have to reset the units sometimes up to three times in order to keem them running. This happens regardless of the outside conditions (day on night). Water filters, towers and pumps all are clean and well maintained. One more thing: whenever they use the system on weekdays, when the weekend comes, most of the units start up without any problem. Thank you for your time and help.

ATS

Are the water control valves all opening up to max flow on start-up by design? What exactly is going on with pressure and water flow? Too little, too warm? If so, maybe stage the units to not come on all at the same time, tdr's perhaps. Is the water tower fan being turned on just prior to starting the units making the cooling-recirc. water to warm hence the high head? Try starting the tower sooner to get the water temp down. Just guessing, we're here, you're there. What kind of facility?

mdshunk

Is this a shell and tube condenser? Perhaps the tubes need brushed out? I know that slime that can build up inside them has great insulating properties. Is the condenser properly sized for the cooling load that will be imposed on it during startup? Are any capacity controls installed? Are they properly modulating? Can you change them so that they'll only operate "half" for a short period until a little bit of space cooling is achieved? Just some thoughts off the top of my head. The stagger starting ATS suggests is a good idea, and starting the tower a good 30 minutes before the DX is a must.

snapperhead

the condensers on the units are the hottest points with the discharge gas going in and picking up the entering water from the tower...this i a big magnet to say as this for algea and dirt to coat the inside of the condenser tubes and cauasing the trips.next time on a reset ofany or all the units grag the Liquid Line and reset the compressor.if the line gets warm to hot within 5 minutes the heat of the gas is not transfering to the entering water and tripping the unit.the more units coming on raise the condenser water temps and add the days temp and your tripping.you need to catch a trippped unit isolate it acid clean it and restrat to see the results.to clean them get a 5 gallon bucket and a tiel pump,drill adapter circulating tool and let the unit water just fill the bucket pour a 1/2 gallon of scale remover in and let it cook for 1/2 hour..have in go in the return water out of the unit for best results