Glycol lines chilling a fermenting beer

[HixFarmBrewery]

We're having an issue where even though the motorized ball valves leading into the tanks are closed in the glycol line, the fermenting beer inside is still crashing during fermentation. We had one fall below 60, so it's more than just ambient temperature (which we keep at 72 anyway). We built our glycol lines using pex with a single motorized ball valve on the drop leading to both inlets and no valves on the outlet side.

Any advice to stop this problem would be great!

Cheers!

[jebzter]

Its clear that you have glycol flow still. My first thoughts would be that the valve is not closing all the way. Assuming it is properly plumbed, that is your only potential source of leakage. One thing to note, as glycol cools a tank, when it hits its set point and the valve closes, the remaining glycol in the jackets is still very cold and will cool the tank further by a degree or two. This could be what you're seeing, in which case you need to adjust your temperature controllers to close the valve a degree or two from the desired setpoint.

[BemidjiBrewing]

You may also have a piece of debris stuck in the valve that is preventing it from fully closing, thus allowing a slow trickle of glycol through the jackets. Was this system recently installed? Everytime we have added a tank, and no matter how much we tell the plumbers to flush the lines prior to introducing glycol, we have seen some debris come through and stick in our solenoids. You should have a wye strainer on the return line near your glycol chiller. Make sure that is clean and operating as it should. You could try opening and then closing the ball valve to help flush any debris through and send it towards this filter basket. Worse case, you may have to disassemble the valve and clean it. This is much easier with a soleniod than a motorized ball valve.

[brewmaster 2011]

Its clear that you have glycol flow still. My first thoughts would be that the valve is not closing all the way. Assuming it is properly plumbed, that is your only potential source of leakage. One thing to note, as glycol cools a tank, when it hits its set point and the valve closes, the remaining glycol in the jackets is still very cold and will cool the tank further by a degree or two. This could be what you're seeing, in which case you need to adjust your temperature controllers to close the valve a degree or two from the desired setpoint.

jebzter is hitting on something close. another thing to add is how long to actuated ball valves take to close and if there is any debris that might be preventing the valves from close all the way.