FV Mystery

[mr.jay]

Any idea why ONE of my FIVE glycol cooled fermenters isn't dropping to desired temperature? It seems quite random, sometimes it happens, sometimes it doesn't. (FYI, volume of wort isn't the issue) I am now waiting on a lager to drop below 48 degrees. Been waiting 3 days now. I originally set it at 43 degrees, and it stopped at 50. Then, I set it to 32, and it dropped a whoppin' 2 degrees. I'm perplexed.

[Charles S.]

If you have solenoid valves with diaphrams, tear it down and check the diaphram for dirt, and sometimes they just need to be rebuilt.

[choicejohn]

Check your temp probe for calibration errors. There may be a temp variance that is mis-reading the true temp and you may be at your target temp already. I had a couple of temp probes suiddenly start reading a 10 to 20 degree variance. I recommend taking a large sample from your zwickel and using a dial thermometer to be sure. Also, it could be your solenoid going bad, but can't hurt to test the temp.

[jimvgjr]

Any idea why ONE of my FIVE glycol cooled fermenters isn't dropping to desired temperature? It seems quite random, sometimes it happens, sometimes it doesn't. (FYI, volume of wort isn't the issue) I am now waiting on a lager to drop below 48 degrees. Been waiting 3 days now. I originally set it at 43 degrees, and it stopped at 50. Then, I set it to 32, and it dropped a whoppin' 2 degrees. I'm perplexed.

Assuming your temperature read out is correct, I would agree that it is likely a solenoid issue or possibly an issue with your temperature controller. I think that taking the solenoid valve apart to inspect would be a good idea. You could also check the wiring to the solenoid coil, confirm that you can hear the solenoid snap open when the thermostat calls for cooling.

Is this problem fermenter located in the same area as the other four, with no significant increase in glycol piping that might result in less flow than the others?

Good Luck,

Jim

[mr.jay]

OK, although I understand how they work, I've never had to take a solenoid apart before. Any resources available to get me through this, or is it easier than I think? I suppose the first order of business would be shutting down the PID panel (yea, I've only been a brewer for 2 years, so please bear with me when it comes to new problems like this).

[choicejohn]

Taking apart a solenoid valve is super simple. I have posted two links to show you how they work. The first is a drawing showing the operation of the valve with parts included. The second is a pic of a solenoid so you know what I'm talking about when I describe how to disassemble it.

http://www.homerepairforum.com/images/uploads/2004-12-31_Solenoid_waer_valve_w550.JPG

http://www.grainger.com/itemdetail_largepic.html?item=XL-3UL34.JPG

All you have to do is cut the glycol going through the valve by cranking the temp up to say, 100 degrees. Make sure you turn the power off after you do that.

What you do next is open the electrical box that is right next to the green magnetic housing that fits over the stem of the valve. Should be 2 little screws, one on each side.

Unwire the 2 or 3 sets of wires in the electical box going to the green housing and cap them so the loose ends aren't touching anything, keeping in memory what wires were twisted together. This is important cause if there is power going to the solenoid and you take it off. the current will fry the coil.

Next, simply loosen the 4 bolts on the brass cap, remove them and slowly pry it off. You may need to use a flathead screwdriver to break the seal since it must have been a long time it was last opened. Be sure not to lose the rubber O ring that makes the seal!

Thats it, take out the spring and cap and make sure it's nice and clean, inside too. Put it all back together doing these steps in reverse and turn the temp back down. You should hear the solenoid click when it turns on.

This is the company who we use for our solenoids and spare parts, fyi:

http://www.grainger.com/Grainger/items/3UL38

If you are uncomfortable with taking apart the valve, give these guys a call or have your Air Conditioning guy shoot out to have a look see. It'll cost ya like $100 for the visit but the piece of mind is worth it for your first time. I had mine teach me everything about the solenoids, glycol plumbing and what not.

Hope this helps ya solve the problem!!

[BrewinLou]

Chillin

Before you go pulling things apart, have you done some of the more obvious? Do a visual inspection of you chiller. All fans running, spray clean the heat exchanging portion, check glycol level. We had a fan with a bad capaciter recently, the fan still ran just slower. Very hard to notice. Is the tank in question the last in line? Does it only do it when you are chilling a heavy load AE lots of tanks or a heat exchanger for you cold liquor?

[beertje46]

Also insure your thermocouple is all the way to the end of the thermowell. I snagged the theromocouple on an old dairy tank and pulled it almost out. The readings I got were as you describe. I pushed the thermocouple back in and it was back to normal.

[GlacierBrewing]

Hiya' Mr. Jay,
In addition to the above solutions, I would suggest you might have sizable air bubbles in the glycol line. If these get trapped at a high point, they could effective act as a liquid brake. Since liguids flow along the path of least resistance, the glycol will shunt to other parts of the system with easier flow. To check this, I suggest you manually shut down as many of the tank's glycol flow as your system permits except for the offending tank. If there is a bubble, the isolated presssure increase should be able to push it along. I installed an air bleed valve on my glycol system at the high point to purge air bubbles.
Luck to ya'
Dave

[mr.jay]

problem solved!

Thank you all, as always, for your concern and input. This was the problem (in case anyone is interested). I went up on the roof and noodled around in the glycol chiller. Everything seemed to work ok, but I noticed the pump was cavitating. Turns out, the glycol level was just low enough to draw air into the line. Filled er' up, and we're back in business!