Jeff Neiman returns to the HVAC School podcast to explain how we can perform leak detection on a low-pressure chiller. Jeff works on systems with glycol loops or other forms of secondary fluids, which may have leaks from time to time. When the chilled water pump on the suction side runs into a vacuum, air can get into the system via the shaft seal. Then, more leaks can occur in the glycol loop as more air goes into the system.

High-pressure chiller leak detection is pretty much the same as on a package unit. However, your typical low-pressure chiller will sit in a vacuum and require us to spend more time on leak detection. These low-pressure systems often have massive amounts of refrigerant below atmospheric pressure. These may have purge units that keep non-condensibles out, but some trace amounts of refrigerant can be vented out with the non-condensibles. Leaks on the low side of the system can cause even more refrigerant venting.

Leak detection on the condenser side of a low-pressure chiller is pretty straightforward; like high-pressure chillers, you can use the same leak detection methods you'd usually use on a package unit or split residential system. When you know you have a leak on the low side, you can turn the chiller off; it will still be below atmospheric pressure, so you'll need to bring up the pressure to find a leak. Otherwise, you can weigh out the charge and flow nitrogen with trace amounts of refrigerant through the system.

Overall, leak detection can take a LONG time on low-pressure chillers.

Jeff and Bryan also discuss:

• High vs. low-pressure centrifugal chillers
• Raising the pressure on the low side
• Submerging leaky components in water
• Leaking in the tubes
• Pressure and its effects on gaskets
• Jeff's leak detection tools
• Open-drive motors

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