Ambient Temperature Issues?

[gdebisschop]

We're having difficulty getting our tanks below 39/40 deg F. Our glycol is returning to the resevoir at 29deg F, so I can't imagine that's the issue. We cool adequately otherwise- crashes go down about 1 deg F per hour, but flatten out in the mid 40's and struggle to go lower. Thinking it might be a flow issue I've restricted cooling to one or two tanks but the issue persists. We have some high ambient temperatures right now- double brew days, a heat wave and no cooling in the brewery have us in the mid 80's to low 90's ambient, but we've also added a few new 40 bbl fv's in the last few months and cooling has struggled since they were introduced as well. We're having a really hard time isolating the source of our issue- any ideas out there?

thanks
geoff

[jimvgjr]

Are you seeing this pretty consistently on all the Fermenters, or slower cooling the further away from the chiller you get? It is surprising that even isolating the one or two tanks you didn't see any improved cooling.

You mentioned returning to the chiller at 29F, what is the glycol supply temperature? Do you have an idea of the flow going out. With that information we can estimate an approximate BTU/HR cooling load the chiller is seeing. I agree it doesn't sound as if your are "over loading" the chiller and would lead me to suspect a flow issue.

Your point about the ambient air is definitely going to also factor in a big way, even with the best insulated tank.

Another issue a customer and I recently found was air in the system, by installing some air vents at the high point helped to bleed out the trapped air and improve the heat exchange. Here is a device available at Granger: http://www.grainger.com/Grainger/items/3TZ96

Hope this helps, please feel free to call with any questions or comments.

Jim
Pro Refrigeration Inc
jimvgjr@prorefrigeration.com
800.845.7781 ext 203

[Scott M]

If your return is 29 deg and the FV is hovering around 40, either you're not getting enough flow through the jacket at the proper rate or the Glycol is bypassing the FV.

The coolant doesn't appear, from the information you've provided; to be picking up any heat from the FV.

Check the temp of the glycol entering and leaving the FV.

It would help to see a schematic diagram of your glycol system.

[gdebisschop]

The glycol resevoir is in the mid 20's, though in the afternoon its in the sun and it does rise. Not sure how to check temps in-line to tanks, but we get ice buildup on the fittings even when the ambient is 90, so I'm sure it's cold enough. I do agree that this seems like a flow issue, but with every tank off and the end loop bypass nearly shut I'm not sure how even one tank cannot cool properly? And if it is flow, would the return be 29F? It is pretty consistent across all fermenters, but slightly exaggerated towards the end of the run- just slightly. We have air vents on the high point of the system, I really don't think it's bound up with air.

thanks
geoff

[Moonlight]

Is it possible that your glycol temp is so cold that you have ice built up inside the tanks where the cooling jackets are?
I assume that your glycol is plumbed to go in the bottoms and out the tops of the tank jackets.
Sometimes a cooling jacket design will cause stratification in the tanks,with pockets of colder and pockets of warmer beer. Is it possible that there is a warmer pocket around the thermwells? This seems unlikely having the same issue on multiple tanks, but you may be able to confirm by checking the temp of a sample from a sample cock if at a different elevation than your thermwell.

Are the tanks insulated and clad or is the glycol jacket exposed to ambient?

[gdebisschop]

We just recently ran the glycol warmer to defrost any ice and increased our glycol %. There's no ice in the resevoir, and we don't ever find evidence of ice post-filtration in the fermenters. Our temps on the readouts are pretty accurate. Not only is this issue across multiple tanks, the tanks range in size from 10-40 bbls and they all behave in the exact same way. Our inlets are on the bottom of the tanks, return on the top. We do experience some stratification of temperature but it's +/- 2-3 deg F, and I think independent of this situation.

Thanks
geoff

[GlacierBrewing]

I've had similar issues with my glycol system in the past. My culprit was an air bubble lodging in and near the high points of my system; usually near the GLYCOL IN of the FVs. I constructed a cheap and effective "screw top" air bleeder from PVC so that I may manually bleed any air out of the system as need.
Check for air bubbles.


Prost!
Dave

[dinobrew]

You could have a tank geometry issue. Water(and beer) is at its highest density at 4C(39F). This beer then sits at the bottom where the probe is with cold beer above it. Try shutting off the top jackets and only when it gets to 39-40F. This may not be the case but it has worked for me when I had similar problems whenever it has happened it has always been at 39F.

[Jim Lieb]

I just had a similar issue, and it turned out that we have a by-pass loop for the glycol so that if the is no call for glycol in the tank farm the system won't freeze up. It turned out the ball valve for the loop was open to far. We closed it a little and the temperatures came down.

Jim Lieb
Rocky River Brewing Co.

[Ted Briggs]

dinobrew- "You could have a tank geometry issue. Water(and beer) is at its highest density at 4C(39F)."

I racked my brain until i dropped my temp probe from my ph meter into the top of my tank though the prv-- 33f on the top and 40f at the probe. (it was easy to sanitize and long enough to hit the wort and read at the same time) For some reason these tanks dont have the thermal convection to mix while cooling. (7bbl Pub) However if i crash 2 tanks at once they get down to 35f-- ie. they cool too fast and create a thermal layer. I actualy opened my bypass loop more.
Check this before you bash your head into the wall--

[Moonlight]

Have you confirmed the accuracy of the thermometer in your glycol tank?

[liammckenna]

You should check the flow of individual tanks. Hassle, but necessary. Do this, preferably, with all tanks open full cooling and then after, evaluate individual tanks (all others off).

Depending on your glycol header loop(s) design, you may need to balance individual tanks on the system. I.e. certain tanks may get too much flow, certain tanks too little - depending on system geometry.

You may need to introduce some ball valves for tanks 'early' in the loop to restrict maximum cooling flow.

Check the by-pass on the cooling plant itself and check the restriction at the end of the feed header as it joins the return header.

We have two loops - our fermentors and another for our conditioning tanks. Fermentors are upstairs, conditioning and bright downstairs.

It took some messing around to make it all good.

Pax.

Liam.