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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a RTAC chiller that is shutting down on gh water

Customer Question

I have a RTAC chiller that is shutting down on high water inlet temp and flow I jump the flow switch and it still shut down
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.

Hello, jumpering flow or high temperature switchs is a good practice for monentary tests, but not run the system, great damage can result if you leave a jumper in place for more than 20 or 30 seconds.... or in some cases even a shorter period of time.

Expert:  Phil replied 1 year ago.

Tell me if the high temperature switch sensor is in the condenser water inlet line, and if the flow switch is in the same condenser water flow loop or if any of these switches is in the chilled water loop.

Expert:  Phil replied 1 year ago.

Tell me please the Brand name and full model number of the chiller and its approximate age... and tonnage rating.

I also need to know if the condenser water is in a closed loop though a liquid cooler or an open cooling tower.

We can go from there.

Customer: replied 1 year ago.
The unit is 80 ton Trane RTAC air cooled chiller
Expert:  Phil replied 1 year ago.

Thanks, ***** ***** air cooled the temperature and flow switches are in the chilled water loop, running chiller with insufficient water flow can freeze the heat exchanger and result in broken tubes and a ruined chiller.

There are 5 to 10 minute time delay relays in those circuits so that you might have to wait awhile for those to time out after jumpering the switches as a test but only a test, a brief less than 2 minute test.

Working on these is generally a factory trained specialty for that specific reason, can you tell me a lot about your background in the trade so that I can coach you most effectively.

Customer: replied 1 year ago.
I am a licened contractor in Georgia with 30 years experience and Trane trained. I have never see this unit shut down on high water supply temp before I have figure it out It's new piping above ground that has not been insulated as yet and the sun is taking the water temp up to 120 degrees. Thanks for your help
Expert:  Phil replied 1 year ago.

THanks, ***** ***** likely have just located the problem, sun heating the chilled water to 120F will hold it off every time.

Is there a orifice plate fit to the chilled water piping so that you can measure the water flow? if not we need a way to figure out how much water is going through the chiller, (and past the flow switch) could be anything from a piping error to an air lock (air trapped as the high point of the chilled water coil(s).

Look that over, let me know what you can discover, we can go from there

Expert:  Phil replied 1 year ago.

Hello again, on thinking about it, the sun would not heat the chilled water inlet up to 120F if there water was circulating, the odds are high that the system is air locked, look for air vents at all high points in the chilled water loop, if they are not there you will have to add them of course,

I will be back in the morning,