Mold?

[monkeybrewer]

Hello All
So I'm still having cooling issues and a thought occurred to me. With these tanks sitting exposed to the elements for 2.5 year, is it possible that bacteria got into my jackets and are now causing an insulating affect. Does glycol even possibly rot at a 50/50 concentration? Doesn't seem likely but I'm almost entirely out of ideas as to why I can't get my tanks below 38F. For the record, the glycol looks perfectly clean. Also, I'm sure I have flow, the glycol is at the temp set on the glycol unit (28F), my temp probes are all accurate and read consistently, I've checked the temp manually with a sample and it was correct, pressure on the return has been reduced to 15psi thanks to partially closing inlet valves on the fermenters, I can see frost on both the inlet and outlet side of the piping on the jackets. I plan on adding water to the system to bring my concentration down to 35gly/65water. But as far as I understand that will just help the unit itself work less and not effect the cooling on the beer. And the capper to this all, is that the system as it is today worked perfectly well for 15 years before the fire shut us down for 2.5 years. Anyone have any ideas or experiences similar to this...I'm going crazy with this problem.
Thanks

[Jephro]

Seems to me a glycol jacket would be a great home to mold. Why not just disconnect & drain your glycol and CIP the jacket? Did the system remain closed while dormant, or where the lines/jackets open?

But... if there was little boogers growing in there you would probably be able to see floaties in your reservoir, it would also clog your screens, possibly the solenoids and most likely cause your pressure differential to be high.

Just curious if you have consulted an HVAC person? There is probably one sitting at your bar
In my mind if everything is flowing freely and insulated properly 28°F Glycol should bring your beer to no less than 32°F-34°F. Have you inspected your solenoids, lines, screens/traps and checked for air in the system (esp. in jackets)?
... just my $0.04

[gitchegumee]

I highly doubt that your propylene glycol is harboring any bacterial/mold growth. Matter of fact, it's used in cigar humidors (and many other applications) to prevent mold growth. This ain't your problem. And the propylene glycol could even go down to 30%, but even at 50% the heat capacity is diminished to only 0.85 (compared to water at 1.00). Although significant, it's not extreme, so I doubt that's your problem. Guess I'm not much help. There are a couple of things I would do though. Open an empty tank and see what kind of cooling you are experiencing. Does the inside of your tank also frost up like the glycol lines? Is it everywhere on the jacket, or are there some dead zone? Sounds like your jacket surface area is compromised. And why on earth would your glycol return header read 15psi? It should be close to zero (unless you have a rooftop unit). All the return header has to do is dump the glycol into a vented tank, no? This takes almost no pressure in most systems. What is restricting your flow and causing your pressure to be so high right next to dumping it into a reservoir? And just in case, dilute your 50% to something more like 30-35%. Hope this helps. Good luck!

[South County]

I highly doubt that your propylene glycol is harboring any bacterial/mold growth. Matter of fact, it's used in cigar humidors (and many other applications) to prevent mold growth. This ain't your problem. And the propylene glycol could even go down to 30%, but even at 50% the heat capacity is diminished to only 0.85 (compared to water at 1.00). Although significant, it's not extreme, so I doubt that's your problem. Guess I'm not much help. There are a couple of things I would do though. Open an empty tank and see what kind of cooling you are experiencing. Does the inside of your tank also frost up like the glycol lines? Is it everywhere on the jacket, or are there some dead zone? Sounds like your jacket surface area is compromised. And why on earth would your glycol return header read 15psi? It should be close to zero (unless you have a rooftop unit). All the return header has to do is dump the glycol into a vented tank, no? This takes almost no pressure in most systems. What is restricting your flow and causing your pressure to be so high right next to dumping it into a reservoir? And just in case, dilute your 50% to something more like 30-35%. Hope this helps. Good luck!

Ditto on the return pressure being at 15 psi, should be next to none. Unless you have a glycol install type unlike the standard, where's Jim on this one?

[monkeybrewer]

header pressure

Hello All
To answer some questions...
Solenoids are new and tested, air is bled from the system and I definitely have flow into and out of my fermenters...

So mold is definitely not it (thanks gitchegumee), the glycol is clean and the cooling works great at the high end of cooling 68F down to 41F...

As for my return line pressure, my pressure reading is directly after the tanks and not right where it dumps into the vented reservoir. It is in fact a roof top installation, so that adds 8 psi to the reading I'm getting from static head pressure (according to our readings before we fired up the system). I can't see how there would be no pressure on the return when cooling is being applied to a tank. My pump feeds at 40psi to the tanks. I restrict flow at the inlet to reduce the pressure out of the tanks to 15 psi. Which means I'm likely putting about 20psi into the jacket with it's restriction dropping the pressure to 15psi. How would this pressure drop to zero when flowing?
One concern I do have is that if I set my bypass valve on the unit to the manufacturers specs, I get tons of back pressure on my return (35psi). I've remedied this by closing the bypass valve almost entirely and just having it trickle back into the reservoir to recirculate. Might my bypass valve on the unit be shot in some way that is causing all of my troubles? I do have the ability to close that bypass entirely and use a ball valve in the brewery to create the bypass manually. Wanted to avoid running glycol through the brewery all the time but at this point I just want results.
Thoughts?

[dick murton]

A few rambling thoughts -

Have you actually checked the flow rate and the cooling area vs the actual cooling required ? It may simply be that the cooling area is inadequate for the volume of beer you are trying to cool. The simpleton in me would simply compare the mass of glycol / hr * temperature difference between the glycol and beer, and the mass of beer * temperature dropped. If the glycol is greater than the beer, and your glycol is still colder than the beer by a considerble margin, then I would reckon on the cooling surface are either being grossly contaminated, or more likely, simply inadequate.

Ifyour return pressure rises to 35 psi when you open the bypass valve, it sounds as thought you have a restriction somewhere in the return pipework. I'm not familiar with fridge calculations, but it just doesn't feel right - the delivery pressure is way too high for the system. I wouldn't like to have that much excess pressure, particularly as the glycol jackets on the vessels I am familiar with wouldn't be rated over about 15 psi - so potential for damage.

Where is your thermometer compared to the cooling jackets ? If it is at the top, you may be suffering from temperature inversion, and the glycol is actually being turned off too early. Temperature probes are normally just above the cone if a CCV or perhaps 25 - 333 % from the bottom if flat bottomed.

[Blaze Ruud]

Tanks in Question?

Jay,
Quick question for you, is it just one tank having this problem or are all of them? Good luck man

Blaze Ruud
Old Schoolhouse Brewery

[monkeybrewer]

Unfortunately...

Yah it's at least two out of my three fermenters with the third finishing up it's first fermentation since the fire this weekend. All of the fermenters showed the same temps before there was beer in any of them (and they were all calibrated together). I did add water to the system to get my glycol down to 35%. Going in to the brewery this afternoon to see if anything has changed. I also closed off the bottom jackets on the two conditioning beers hoping this would help (the yeast has been harvested and dropped from both beers already).
Cheers

[dast]

Hi,
You will definately get an improved thermal conductivity with a lower concentration of glycol (probably 22% to 24% improvement of the thermal conductivity in your case)so that should help. What you also get is a lower viscosity (about 47% to 57% less) so that will also help the efficiency.
I guess you have allready checked that your supply connections to the fermenters are correct (supply connected to the lowest connection on each jacket and return conected to the highest connection on each jacket) and I assume they arre connected parallel and not in series. So next listen to your piping if you hear fluid pumping around in it you normally still have some air in the system, if so try to get it out. Please also be aware that solenoids have a big flow restriction and if they have clogged with debris/dirt you will get a very poor perfomance.
How many cooling jackets do you have totally and what is the size of your piping? If the piping is to small you get a poor performance.
Do you have sufficient insulation on you piping? If not you can loose a lot of power here.

Cheers,

Dan Strömberg
Market Segment Manager
Cooling & Refrigeration
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Georg Fischer LLC
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dan.stromberg@georgfischer.com

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[monkeybrewer]

It's working a bit better but not all the way yet...

So, adding water to the system to get a 35% glycol/65% water mix has gotten our beers down to 36F. Definitely a couple degrees improvement there. I've definitely got flow through the jackets from low to high. I can feel how quickly cold glycol enters and exits the jacket, and it is quick, so I'm sure we have more than adequate flow through the jackets. The piping to the jackets has actually been increased from 3/4" to 1 1/4" so no issues there. I have frosted return and supply lines when cooling is being called for. I just started insulating the lines but feel confident it was the not the problem as I was still getting below freezing glycol to and from the jackets (thus the frosted pipes to and fro). And all of the fermenters are connected in parallel and there are air bleeders on each tank at the highest point on the tanks glycol piping that did bleed air upon start up (have not since). Tomorrow I cool down the last tank with things setup better than the other two cool downs...hopefully I will see an improvement over the others. Any other thoughts about why I can't get this system to perform as it used to (Before the re-installation I was able to cool a beer from 68F to 32F in less than 24 hours)?
Thanks for the continued help everyone!
Cheers

[gitchegumee]

Jeez man! Sounds like everything is working as it should except the laws of thermodynamics. I'd like to reiterate that you might want to open an empty tank and see/feel where the cooling goes when it's on. If, for example, you had some kind of gunk clogging most of your jacket, you would get freezing glycol on exit with little tank cooling. Should be able to see/feel the cooling trace. I can't imagine any other scenario other than insufficient heat exchange area. Two other things: 1) I hope you figure this out and deliver us a novel new solution to fix a frustrating problem. 2) I hope this never happens to me.