Glycol system troubleshooting

[ERoss]

Hey all, I am having some issues getting my glycol unit to chill my brite tank down.

I have mixed my glycol to approximately 30% glycol 70% water as this seems to be the mixture that we need here. The chiller unit is set to -3C (26f) and the glycol is flowing through the loop as far as I can tell. I have closed the drop to 2/3 of our tanks and am just testing out the brite tank, however the tank only dropped 4C in 24 hours, which seems to be a very slow temperature drop. The tank was at 11C and is now at 7C. I should also note that from day 1 to day 2 it dropped from 22C to 11C, but the temperature probe was not properly placed in the jacket. I have the tank set down to 3C. Any ideas on what could be happening?

As a side note this morning I noticed that the supply line on one of the closed tanks is cold, but not the third tank. Also, our plumber installed the solenoids on the return line, but I don't know if this is causing issues or not.

Thanks for any advice you can provide, it is much appreciated.

[TGTimm]

I can't help with your bright problem, but having the solenoid valves on the return side of your jackets is a great way to ruin your cooling jackets. the return side should never be blocked when the feed side is open. The "water hammer" effect when the solenoid valves close will over-pressure the jackets in a sudden burst, and, sooner or later, the jackets will start leaking at the welds.

[ERoss]

Thank you for the heads up, I will be calling my plumber in today to fix it. In the meantime I will be shutting down the cooling system to prevent damage.

[DowneastCider]

Thank you for the heads up, I will be calling my plumber in today to fix it. In the meantime I will be shutting down the cooling system to prevent damage.

When you shut it down make sure the solenoid valves remain open (while they are on the return waiting to be moved). If the cold glycol flow in the jacket is stopped because of a closed valve, when the glycol heats up it will expand and ruin your jacket.

[TGTimm]

The problem of having the return valves closed is so serious I've removed the handles from the isolation ball valves on the return lines to prevent accidental closure. When working on the system, the return valves are the last closed, first opened.

If you've never had to repair a leaking jacket weld, let me tell you, it's not fun nor pretty.

BTW--this may seem obvious, but it can't hurt to ask: Are you sure that the supply and return lines are correctly connected? Supply to the bottom fitting on the bright, return to the top. Reversing this results in stratification and little or no cooling.

[ERoss]

Noted. I definitely don't want to deal with that. Supply and return lines have been run correctly, on both the jackets. Solenoids are being fixed as I type this, and our chiller manufacturer is sending us a new temperature probe as well because the probe on the chiller was reading 5C different than the glycol in the reservoir as of this morning.

[ERoss]

Your glycol mix sounds a little lean for the temperature you are running at. You might want to check the manufacturer's specs, I'm thinking at least 35% glycol.

As was stated by another contributor, you want the glycol running in at the bottom, out at the top. If you have any points in your distribution manifold where the glycol is running downward, you have potential for an air-lock and you may need to install a bleeder valve at the top end of the downward run.

I have measured my glycol mix and it is at 33%, I was off on my initial measurement. We have an airbleeder on the line, and the drop is installed correctly. As of today the system seems to be working properly. I think switching the solenoids over made the difference as the system is cooling at a decent rate and holding temperature in all the tanks.

Thanks for everyone's contribution, it definitely made a difference being able to troubleshoot with more experienced folks.

Cheers!