Conical Cooling Conundrum (Spike CF10)

[mongoose33]

See attached pic.

I have a 33% Glycol-67% Water mixture in a reservoir in my ferm chamber refrigerator. The system does well at moving temps down to the low 40s, but now, I can't complete a crash to 32 degrees.

Since last night, when the temp was 39.1, the temp this morning was 38.7. It simply isn't cooling, and I don't know why.

Five Gallon Batch (maybe 6 gallons in the fermenter).
Ambient in the garage: 64 degrees.
Conical wrapped in moving blanket down to floor.
Two towels on top cover the portion I can't reach w/ the moving blanket.
Condensation on both supply and return lines; they're cold.
Tilt Hydrometer in Conical confirms temp read on temp control.

Morrey does something similar with his SSBrewtech unitanks. He feeds his with a Penguin chiller which is much more responsive to temp than mine, but he keeps his at 28 degrees.

Mine is one degree lower--and the reservoir temp is more than low enough to take this down to 32 degrees.


Why? Is it possible I'm forming ice on the coils and that's limiting cooling? @Morrey suggested raising the temp of the coolant to 30 degrees. The only other thing I can think is that there's so much heat gain into the fermenter that it's offsetting the cooling. If so, how do any of the rest of you manage this?

To reiterate: it's not the temp of the reservoir. It's plenty cold, and recovers well.

 

[auburntsts]

Have you verified the flow of coolant through the system? Maybe the pump isn't working right or there's some kind of blockage in the tubing/coil that's limiting flow.

The only other suggestion would be to verify that the temp probes are reading accurately.

 

[mongoose33]

Have you verified the flow of coolant through the system? Maybe the pump isn't working right or there's some kind of blockage in the tubing/coil that's limiting flow.

The only other suggestion would be to verify that the temp probes are reading accurately.

Yeah, there's flow of coolant through the system; both lines are very cold, and both show condensation. If the flow was blocked, they'd be warm.

And the TILT confirms the temp of the temp probe in the thermowell.

*************

I ran home to check, and the temp had risen from 38.7 to 40.5 so there clearly is heat gain. I raised the temp of the reservoir to 32, and we'll see if the temp drops from that later today.

 

[auburntsts]

Yeah, there's flow of coolant through the system; both lines are very cold, and both show condensation. If the flow was blocked, they'd be warm.

And the TILT confirms the temp of the temp probe in the thermowell.

*************

I ran home to check, and the temp had risen from 38.7 to 40.5 so there clearly is heat gain. I raised the temp of the reservoir to 32, and we'll see if the temp drops from that later today.

Maybe not blocked but there could be a restriction. Also if the pump isn't working right you might not be getting sufficient GPH even though some coolant is pumping. Just because the lines are cold doesn't necessarily mean you have adequate flow and cooling. Just food for thought.

My only other suggestion is see if reducing the reservoir set point a couple of degrees more makes a difference. Maybe with the smaller batch the conical's coil is simply less efficient as less surface area is immersed in the wort so requires the coolant to be colder than say for a 10 gal batch.

 

[mongoose33]

Maybe not blocked but there could be a restriction. Also if the pump isn't working right you might not be getting sufficient GPH even though some coolant is pumping. Just because the lines are cold doesn't necessarily mean you have adequate flow and cooling. Just food for thought.

I checked the pump; it's drawing liquid at the same rate as always.

My only other suggestion is see if reducing the reservoir set point a couple of degrees more makes a difference. Maybe with the smaller batch the conical's coil is simply less efficient as less surface area is immersed in the wort so requires the coolant to be colder than say for a 10 gal batch.

Yeah, it's possible the coil just isn't deep enough in the beer. I still had this sense that perhaps I'd frozen the beer, but I've kind of discounted that theory--the beer should be about 5% alcohol, which would drop the freezing temp about 3.78 degrees fahrenheit, plus the beer is under pressure (10psi). I had the reservoir temp at 27, and the beer hasn't dropped below about 39.

I'm wondering if I just need to build a chamber to insulate it, using something like 2" thick foamboard as the walls.

Is anyone else having trouble crashing a CF 10?

 

[auburntsts]

Hope you figure this without too much effort. This is exactly the kind of issue I was wondering about in my CF5 vs CF10 thread.

 

[Sconnie12]

Why are you trying to crash to 32F? All the commercial brewers I've talked to have said 35-38F. I do mostly 5g batches in my CF10 and have had 0 issues crashing to 38F.

 

[mongoose33]

Why are you trying to crash to 32F? All the commercial brewers I've talked to have said 35-38F. I do mostly 5g batches in my CF10 and have had 0 issues crashing to 38F.

I've always done it that way. Various recommendations suggest anywhere from 32 to 40, and i was thinking that if I could chase this down to 32, it would have a better chance of at least getting the beer reasonably cold-crashed in the midst of a summer heat wave.

 

[auburntsts]

If it does end up being a coil issue, one solution might be to fab a separate coil for the smaller batches that puts the majority of the surface area at the bottom of the coil, kinda like the shape of an immersion chiller just not as large in diameter vs. the current coil which evenly distributes the coils from top to bottom which leaves a major portion unsubmerged.

 

[mongoose33]

If it does end up being a coil issue, one solution might be to fab a separate coil for the smaller batches that puts the majority of the surface area at the bottom of the coil, kinda like the shape of an immersion chiller just not as large in diameter vs. the current coil which evenly distributes the coils from top to bottom which leaves a major portion unsubmerged.

I'd hate to have to do that. The whole idea of the CF10 is that I can do both batch sizes. I paid $375 plus tax for the heating/cooling option; if it can't do the 5-gallon batches effectively then I've wasted my money, and I'd have been better off finding a big enough refrigerator to hold the entire thing.

 

[auburntsts]

I'd hate to have to do that. The whole idea of the CF10 is that I can do both batch sizes. I paid $375 plus tax for the heating/cooling option; if it can't do the 5-gallon batches effectively then I've wasted my money, and I'd have been better off finding a big enough refrigerator to hold the entire thing.

Agree. Hopefully it's something else, but I sure want to know before I pull the trigger myself since my primary batch size will be 5 gal.

 

[mongoose33]

Agree. Hopefully it's something else, but I sure want to know before I pull the trigger myself since my primary batch size will be 5 gal.

I knew going in that it was going to be difficult to cool or heat depending on ambient. There are all sorts of radiators sticking out of that conical that either shed or draw heat depending on ambient temp--three legs, thermowell, sampling port, racking port, dump port, gas manifold....

That's why I decided to try wrapping it up first. I'm actually surprised it doesn't seem to work all that well; it's not much different than wrapping a mash tun in a blanket to hold heat, and the temp difference between a mash tun and ambient is much greater.

This is all the more surprising to me, as I figured the weak link in the setup would be whether the freezer could keep up with the chilling needs. As it happens, I apparently figured that one out, but not the rest.

 

[Sconnie12]

Agree. Hopefully it's something else, but I sure want to know before I pull the trigger myself since my primary batch size will be 5 gal.

For the record my CF10 works perfectly fine with 5g batches. I cold crash to 38F. IMO 32F is excessive and the 'issue' is user based.

 

[mongoose33]

For the record my CF10 works perfectly fine with 5g batches. I cold crash to 38F. IMO 32F is excessive and the 'issue' is user based.

So you're saying the system shouldn't be able to get down to 32? And what happens when ambient in the garage is 20 degrees higher?

You may like 38. As I'm sure you'd be the first to admit, there are multiple ways to run a railroad, and yours is not the only way.

 

[Sconnie12]

I can't comment on the system getting down to 32F as I've never tried. I've had my conical in a cold garage and inside my warm house; I've never had an issue. I'm going off of what multiple professional brewers have told me they cold crash at. You're try to crash below what is recommended which is what I suspect is causing issues.

 

[Dcpcooks]

What’s the volume of the reservoir? Do you have coils in the glycol? My hunch is lack of BTU capacity and heat transfer abilities.

The average fridge has about 800 BTU’s. A 1/2 hp penguin chiller is 2400 btu’s. Additionally the coils in the chiller are in the glycol which aids heat transfer.

You should insure your coils are fully submerged in the conical. I would lower the fridge temp to 25-26 degrees and see what you get. I played with various sized reservoirs and fridge set ups before I purchased a chiller. I brew half bbl batches and I could never achieve Lager temps until I got a chiller.

I have one 1/2 bbl conical in a commercial fridge and that unit struggles to get below 36-38. After several days it will get down to 34. The fridge is a large commercial unit with 1600 btu capacity.

 

[mongoose33]

What’s the volume of the reservoir? Do you have coils in the glycol? My hunch is lack of BTU capacity and heat transfer abilities.

That originally was a concern, but the system has had no difficulty maintaining a 28-degree temperature in the reservoir. If you look back at the original pic, you'll see that. BTW, I added a copper coil and a heat sink to the reservoir to help overcome the difficult of cooling a "block" of fluid. It appears to help quite a bit.

I didn't want to have to buy a chiller if I didn't have to, which is why I went the freezer route. It actually works. Here's a link to the post describing it:

https://www.homebrewtalk.com/forum/...and-best-practices.645440/page-6#post-8280727

I went back and reread that post, and at that time, when ambient in the garage was 65 (same as now), I dropped the temp from 50 to 36 in 3 hours and 40 minutes. And now, I can't get it to go below about 38. I do not understand why. Maybe @auburntsts is right about a blockage, but it seems to draw through the pump the same as always.

Sudden thought: I'm going to check connections in the reservoir; maybe there's a leak at the output side that spills back into the reservoir.

The average fridge has about 800 BTU’s. A 1/2 hp penguin chiller is 2400 btu’s. Additionally the coils in the chiller are in the glycol which aids heat transfer.

You should insure your coils are fully submerged in the conical. I would lower the fridge temp to 25-26 degrees and see what you get. I played with various sized reservoirs and fridge set ups before I purchased a chiller. I brew half bbl batches and I could never achieve Lager temps until I got a chiller.

I have one 1/2 bbl conical in a commercial fridge and that unit struggles to get below 36-38. After several days it will get down to 34. The fridge is a large commercial unit with 1600 btu capacity.

If you look at the above link to the post on my build, you'll see how I did it. Since this worked once, I don't know why it's not working now to the ability of the earlier attempt.

 

[mongoose33]

I can't comment on the system getting down to 32F as I've never tried. I've had my conical in a cold garage and inside my warm house; I've never had an issue. I'm going off of what multiple professional brewers have told me they cold crash at. You're try to crash below what is recommended which is what I suspect is causing issues.

Actually, some professional brewers apparently prefer 36, not your 38:

https://spikebrewing.com/blogs/ask-a-pro/cold-crashing

And then there's this: http://discussions.probrewer.com/showthread.php?45634-Cold-Crash-SOP&p=135560#post135560

The pertinent quote: "We cold crashed our last brew in a 7bbl fermenter from 70F to 32f in aprox. 24 hrs. " At least one other in that thread does the same.

I guess the idea that 38 is how it should be isn't an idea that is universally-held, is it?

 

[Surly_goat]

Don't get your glycol too cold. I put mine at -10c the first time because I was impatient. Got a nice pilsicle from it and some 6-8% Pilsner.

Temperatures got near zero and then after a while started floating around 3-4c.

 

[Sconnie12]

I'm just going to say lol because I'm done telling you what others that do this for a living told me and have you Google a random link to try and prove 'me' wrong.

 

[mongoose33]

I'm just going to say lol because I'm done telling you what others that do this for a living told me and have you Google a random link to try and prove 'me' wrong.

Didn't just try. Did it. First link I clicked, and there were multiples there, as well. I'm always a little amused, and a little dismayed, at people who think they know everything because they talked to a couple people.

And you think the Spike link was spurious? Hilarious! I guess your guys know it all, though.

 

[mongoose33]

Don't get your glycol too cold. I put mine at -10c the first time because I was impatient. Got a nice pilsicle from it and some 6-8% Pilsner.

Temperatures got near zero and then after a while started floating around 3-4c.

This is one thing--ice--I was concerned with. I don't think it's likely, but you never know. I turned up the temp earlier today to see if I could melt off any potential ice. Just got home to check, the temp of the fermenter was 42, which I would think would get rid of some of the ice, if any.

I checked to see if there was a leak coming out of the pump that would have reduced throughput, didn't find one.

I thought of one other thing to try--when I get home, I'll take my thermapen and check the temperature of the returning glycol mixture and see if it's actually rising in temp after going through the conical.

This is driving me nuts. I did the dry run (well, star-san run ) to check and see if the system was robust enough to do this, and it was, with room to spare. And now it's not working to that level.

 

[Dcpcooks]

I think it’s directly linked to batch size. If your at 6 gallons in a conical that’s designed to cool 10 gallons your coils are partially submerged. Couple that with a smaller than desired btu set up and you have a system that’s hitting it limits.

I’ve experienced a similar issue with the ss brewtech coils on small batch sizes before I mounted them on the side of the conical. I wasn’t getting enough contact area on the beer for an efficient heat transfer.

Have you checked the temp on the return side of the set up? If your return temp is the same as your set point then your not pulling the heat out of the beer and I think that would be a sign that heat transfer/ coil depth is the issue. If your return is at at the beer temp then it’s a btu issue. I could be wrong but I think that makes logical sense.

You didn’t waste your money btw. I’m sure your beer will be fine crashed to 39 degrees. Granted it’s not what you wanted but it’s still going to drop the yeast and clear.

 

[Dcpcooks]

Have you confirmed all your controllers are calibrated to the same temp?

 

[mongoose33]

I think it’s directly linked to batch size. If your at 6 gallons in a conical that’s designed to cool 10 gallons your coils are partially submerged. Couple that with a smaller than desired btu set up and you have a system that’s hitting it limits.

I’ve experienced a similar issue with the ss brewtech coils on small batch sizes before I mounted them on the side of the conical. I wasn’t getting enough contact area on the beer for an efficient heat transfer.

The coils certainly are not completely submerged. The only thing that makes me think this isn't entirely what's happening is when I did the "dry" run with 6 gallons of Star-San, and it had no difficulty bringing things down in temp. Now, difficulty. Same volume.

Have you checked the temp on the return side of the set up? If your return temp is the same as your set point then your not pulling the heat out of the beer and I think that would be a sign that heat transfer/ coil depth is the issue. If your return is at at the beer temp then it’s a btu issue. I could be wrong but I think that makes logical sense.

You didn’t waste your money btw. I’m sure your beer will be fine crashed to 39 degrees. Granted it’s not what you wanted but it’s still going to drop the yeast and clear.

I checked the return temp tonite; 35.8 degrees measured with a Thermapen Mk IV. So it's drawing in heat. See pic below of the temps at the time, reservoir temps on the left, conical temps on the right:

 

[mongoose33]

Have you confirmed all your controllers are calibrated to the same temp?

Yes. I have a Tilt hydrometer inside the fermenter, it's confirmed the conical temps on the conical controller. The controller managing the reservoir temp is confirmed by the Thermapen.

Not a bad idea. But not it.

 

[tjpfeister]

Im dealing with similar difficulties, diminishing returns from chilling. I use a dorm fridge converted to hold 10 gallons of solution at 20F that (now) chills two 14gal conicals.

Though youre not doing yourself a favor with a partial size batch- thats likely not the problem as I have the same difficulty on my BruGear unit with a 50' coil of 1/2" tube fully submerged powered by a 1gpm pump. Those pictures of icing around the coils got me wondering though.

I don't have an answer-answer for you, unfortunately. But two thoughts. From the picture I assume your pump is submerged in the glycol, so this is not likely, but I believe the mechanical heat generated by my diaphragm pumps raise the temp of my glycol a bit before they reach the vessels... I've been tempted to move them to the return side and see if they can pull through the coils more effectively. But if youre using an impellar style pond pump submerged in solution, this is not likely a problem, nor could you reposition it in your system.

The icing thing still concerns me, it happens on car AC systems that get overcharged... But if your returning glycol is 35, I dont have an answer, with insulation it seems unlikely youd pick all that up on your return line.

If I step my crashes down, like:
70-55-45-40-37-35-34-32
I get better results, as Im sure youve noticed yourself, because the tank better recovers and the lower temp can hammer down to your next set point. I have achieved 30F with this method.

After reading this thread (and realizing that so many have a tenuous grasp on fluid flow and thermal dynamics) Im considering raising the temp on my reservoir just to see if it works... But as I type this I can think of a counter-argument: if Im filling my kegs with 32F beer, then the coils would likely be iced, and when I go to clean the conical later, that melt should be in the cone. But I havent noticed that; yet. Curious.

Well, outta time. Gotta go to my real job. Good luck!

 

[mongoose33]

UPDATE:

I had a thought on the icing hypothesis, and decided to check the TILT this morning: SG of 1.007.

The fermentation finished at 1.009, sat there for a couple days. Now it's at 1.007. I pulled a sample, warmed it, degassed as much as I could,checked it with a finish hydrometer; yep, 1.007.

BTW, the beer tastes fantastic; I'm at 10 days after brewing and it's delicious now. Anyway....

I've never had a fermentation finish at 1.007. That's suggesting to me that there's ice, and it's pulling water out of the beer. If I understand gravity correctly, ethanol has a lower gravity than water; pull the water out, the gravity of the remainder will drop.

I've unwrapped the fermenter and shut down the cooling. I'm going to let it sit today and warm up a bit, and see if the gravity changes. I'm betting it will.

 

[tjpfeister]

UPDATE:

I had a thought on the icing hypothesis, and decided to check the TILT this morning: SG of 1.007.

The fermentation finished at 1.009, sat there for a couple days. Now it's at 1.007. I pulled a sample, warmed it, degassed as much as I could,checked it with a finish hydrometer; yep, 1.007.

BTW, the beer tastes fantastic; I'm at 10 days after brewing and it's delicious now. Anyway....

I've never had a fermentation finish at 1.007. That's suggesting to me that there's ice, and it's pulling water out of the beer. If I understand gravity correctly, ethanol has a lower gravity than water; pull the water out, the gravity of the remainder will drop.

I've unwrapped the fermenter and shut down the cooling. I'm going to let it sit today and warm up a bit, and see if the gravity changes. I'm betting it will.

I like where your head is at! My only concern is that ice not only increases alcohol concentration (lower sg) but would increase residual sugar concentration (higher sg). I need to borrow the borescope from work, grow a pair, sanitize the camera end, and plunge it into a perfectly good batch of beer! Lol

 

[tjpfeister]

But now im questioning what happens to the sugar during freeze distillation.

 

[auburntsts]

But now im questioning what happens to the sugar during freeze distillation.

Chemistry class was too many years ago, but wouldn't it stay in mostly in solution just like the salt in saltwater when it freezes?

 

[Surly_goat]

Lol just take off the lid and look inside man. There's breweries that do entire open ferments. Don't go running around throwing confetti while you do it but it'll be fine. You will see the ice immediately if there is any.

Either way I'm sure this wasn't the only batch your ever gonna make You can always make it again. Stronger, faster. Just don't lower your res below 33f.

 

[tjpfeister]

On the surface that seems like the simple answer- but for the ice forming under the liquid level (in my case) as the coils are fully submerged and cannot be lifted out on either vessel. OP might have something visible with his coil partially submerged.

 

[Surly_goat]

Got a long stainless steel anything? Spoon maybe? Poke it! Poke her like she gave verbal consent!

 

[mongoose33]

Lol just take off the lid and look inside man. There's breweries that do entire open ferments. Don't go running around throwing confetti while you do it but it'll be fine. You will see the ice immediately if there is any.

Either way I'm sure this wasn't the only batch your ever gonna make You can always make it again. Stronger, faster. Just don't lower your res below 33f.

Certainly I could do that, but this was a Low Oxygen batch (one of the reasons I bought the conical is so I could do this), and I want to get that beer into a purged keg without any exposure to oxygen.

The beer samples I've had from this have been tremendous, and I don't want to compromise it if I don't have to. I'm still fairly new at LODO brewing and still trying to see if it's worth it in the end, so looking inside, at this point.....

 

[mongoose33]

UPDATE, II:

Came home tonite, fermenter had warmed to 57. No more ice. Drew a sample....1.007. No change from earlier.

So I don't know. I'm back to cooling it down, I want to reabsorb as much CO2 as possible, and then I'll rack to keg. Still tastes terrific, but I don't know what's going on w/ the cooling. Out of ideas.

 

[mongoose33]

UPDATE III:


Tried two more things today; one was to reverse the flow of the chilling liquid through the coil, and the other was to take the copper coil in the freezer compartment out of the loop, thinking that perhaps it was offering too much resistance and slowing down the flow of chilling liquid. Neither made any difference whatsoever.

I transferred the beer to keg tonite, opened up the fermenter: no ice.

The beer is excellent, but I'll be darned with why I can't get that to drop tje temp below about 41. I appreciate all the ideas above, they were all reasonable and worth a shot. I'm going to talk to Spike about it, see if they have any ideas. I've attached a pic showing the coil and you can see the krausen line. That should have been plenty down in the beer to chill it.

 

[btcost]

Great thread.
It looks like you had a 10 degree delta. The glycol was at 28 and the beer maintained 38.

10 degree delta is about as good as is gets. Maybe if you had a much larger supply of glycol (like 10gallons) then you could get the delta even lower. (Beer temp closer to glycol temp)

With that not an option, you simple need a lower glycol temp. If you want the beer @ 32. Then your glycol needs to be 22.

 

[auburntsts]

Is the krausen line you are talking about on the coil or on the side of the tank? I realize the coil is attached to the lid so it's being tilted so you can take the pic, but it seems to me if you had around 6 gal in the conical that only 3-4 of the coils were actually in the wort which would possibly lead to lack of cooling performance. Anyway you could put an identical amount of water that you had in the last batch into the conical and rerun the temp tests and then try it with 10-11 gals to see if there's a difference?

 

[mongoose33]

Great thread.
It looks like you had a 10 degree delta. The glycol was at 28 and the beer maintained 38.

10 degree delta is about as good as is gets. Maybe if you had a much larger supply of glycol (like 10gallons) then you could get the delta even lower. (Beer temp closer to glycol temp)

With that not an option, you simple need a lower glycol temp. If you want the beer @ 32. Then your glycol needs to be 22.

I'm pretty sure that if I had a glycol temp of 22, I'd have water frozen on the coils. That was an earlier hypothesis, but one I think I busted.

I suspect that if I had a 10-gallon batch it wouldn't be so bad--there are so many "radiator fins" sticking out of the conical that I think they're drawing in a lot of ambient heat, despite covering the fermenter with a moving blanket. The thermal mass of the beer would increase but not the heat gain, so it might d better that way.