Temptek Chiller Specifications

8.3 INHIBITED PROPYLENE GLYCOL

To operate liquid chillers below 48°F, it is necessary to add inhibited propylene glycol to the circulating system to lower the freeze point and prevent damage to the cooling system. Inhibited propylene glycol contains corrosion inhibitors which are compatible with most industrial heat transfer surfaces. Inhibited propylene glycol is manufactured by:
• Dow Chemical - “DowFrost” (1-800-258-2436) • Monsanto “Therminol FS” (1-800-459-2665)
• Temptek “Thermofluid” (1-317-887-0729)
Automotive anti-freeze must never be used in industrial heat transfer applications. Automotive anti-freeze contains silicate type corrosion inhibitors designed to be compatible with automotive components. In an industrial application, the silicates will form a gel on the heat transfer surface which will result in substantial reduction in cooling capacity and is virtually impossible to remove.

So, a 50F limit would be safe for a water only system. With the glycol that we are using, we are safe in any current operating scenario.
If the ambient temperature goes below 38F, then there are pressure switches that will be triggered.
If the ambient temperature gets too high (an unspecified upper limit, but likely >95F - which is what we hit in the UT lab without failure) then the safety shutdown is triggered.