We hope all our friends in the storm are fairing well! I saw this email go out to our Technicians and thought I’d share. If your chiller system is down, please share this with your service technician- could save some time getting things operating again. If you need help, give us a call or email us at TechSupport@prorefrigeration.com.

(Email from Damon Reed to Pro Chiller Technical Team)

“The weather forecast this week throughout a very large portion of the Midwest has 20 yr. record lows through most of the region, highs below zero…below -10F even! Want to get this out to you all before I board.

We can likely expect plenty of calls coming into us for support with LP Freeze alarms and questions about how our condenser fans, LP Bypass and Extreme Low Ambient solutions work. I’d like to take this time to explain these items so that we are all on the same page with our communications.

Low Ambient Bypass Timer
All chiller systems without a TCC or CR110 control have a Low Ambient Bypass Timer, when the system engages the cooling demand, we bypass the Low Pressure switch that turns on the compressor for 30 seconds, this forces the compressor to operate and get the refrigerant flowing and take advantage of some compressor motor and crankcase heat to help pressures come up to where they should be.

Low OSA Settings On Microprocessor Controlled Systems
On all systems with the TCC and CR110 we utilize an ambient temperature sensor and have a setting in the controller that is set to ignore the Comp On pressure setting for 60 seconds when we start a compressor. The temperature setting by default is set to +20F. The mechanical principles are the same as outlined above for the Low Ambient Bypass Timer.

Extreme Low Ambient Option
On any system that has the Extreme Low Ambient option installed, we utilize a flooded head pressure control valve and/or an Insulated & Heated Liquid receiver. The flooded head pressure control valve (headmaster) loads the condenser with some liquid refrigerant to reduce the amount of surface area exposed to low ambient temperatures, this lets the head pressure at the compress build up. On all systems with a flood valve, the Header End Condenser fan should turn on/off with the compressor. We cycle the opposite fan based on head pressure setting. The flood valve will maintain head pressure of no less than 180 psig for R22 systems and 210 psig for R404a systems. The secondary condenser fans should be set to not be operating below 250 psig.

Insulated & Heated Receiver Option
On systems with a heated/insulated receiver, the liquid receiver is heated based on a pressure control switch that is set to maintain the pressure in the receiver at 180 psig. This feeds the system with higher pressure liquid refrigerant at startup and ensures we maintain adequate suction pressure to run the system.

Glycol fluid concentration is going to be talked about a lot this week I would anticipate. Our recommendation is that the concentration be set no higher than 20F below the system setpoint OR to provide adequate freeze protection to the lowest ambient temperature. We’ll probably have lots of customers who are running their fluid temperatures at 0 to -10F, hopefully this week we’re talking with folks closer to -10F. The pumps and the system running are going to supply some heat load to the system to help against the low ambient. Any fluid that isn’t protected to the low ambient that becomes stagnant in a line or if pumps shut down is going to be exposed to potential freezing. Let’s keep this in mind with these folks throughout the week.

For customers that need a temporary solution to add some heat to their system and they don’t already have one of the options listed above, I’d recommend they utilize a heat lamp, directed towards the refrigerant receiver, make sure their glycol concentration is adequate, and keep the process pump running (don’t shut it off and don’t use the Enersave feature). Dairy farms will be shutting off process pumps to wash. If they need to do this, one solution to keep fluid moving in the system is to set the circulation pumps to run all of the time. This will at least protect the chiller circuit.

If anyone has comments or questions regarding this – drop me a note. I’m going to head to board plane and will be in Oakland in a couple hours.”


Be safe everyone!

Jim VanderGiessen
ProChiller