Glycol chiller issue

[Rob2010SS]

Having a weird phenomenon happen at the brewery. We are running 2 CF30's on a 1/2 HP penguin chiller with the glycol set to 28F. I can consistently maintain 36F on the crash. However, the minute I try to go lower than that on either tank, I end up with the tank getting WARMER and getting stuck at 37F.

I have both running currently with 40 gallons in each tank. For the past week, they've maintained 36F. Started carbonating one of them. After realizing that I can't get the PSI in the one tank high enough for the carbonation level I want (max 15 psi) I figured, OK, we'll try and cool it down a bit more to try and achieve more CO2 absorption. So I set the inkbird to 34F. Within a couple hours, the temp on that tank jumped to 37.2F while the other tank maintained 36F. Even this morning, it's still sitting at 37.1 and the other one is at 36 still.

I've had this happen before and forgot that we can't try and chill below 36. What I can't figure out is the mechanics. Why is that happening? Perhaps with the chiller running through the coil in the CF for that long, it froze and is keeping the beer from going colder? If I wasn't canning tomorrow, I'd de-pressurize and open it up and see but I don't want to do that.

Thoughts?

 

[bmc1313]

Did you get this figured out? I’m interested in the cause as well.

 

[Rob2010SS]

I have not. I've kind of just accepted that 36 is as low as I can crash for the time being.

 

[stealthfixr]

Having a weird phenomenon happen at the brewery. We are running 2 CF30's on a 1/2 HP penguin chiller with the glycol set to 28F. I can consistently maintain 36F on the crash. However, the minute I try to go lower than that on either tank, I end up with the tank getting WARMER and getting stuck at 37F.

I have both running currently with 40 gallons in each tank. For the past week, they've maintained 36F. Started carbonating one of them. After realizing that I can't get the PSI in the one tank high enough for the carbonation level I want (max 15 psi) I figured, OK, we'll try and cool it down a bit more to try and achieve more CO2 absorption. So I set the inkbird to 34F. Within a couple hours, the temp on that tank jumped to 37.2F while the other tank maintained 36F. Even this morning, it's still sitting at 37.1 and the other one is at 36 still.

I've had this happen before and forgot that we can't try and chill below 36. What I can't figure out is the mechanics. Why is that happening? Perhaps with the chiller running through the coil in the CF for that long, it froze and is keeping the beer from going colder? If I wasn't canning tomorrow, I'd de-pressurize and open it up and see but I don't want to do that.

Thoughts?

I see the same thing on a smaller scale with my CF5 and CF10. I have also made Beer-sicles around the coil when below 28F, and then the jump warmer is even more pronounced. For some reason, I can get my CF10 colder with 5 gallons in it than my CF5 with 5 gallons in it--something about the chilled space above the beer. I would love to get lower, but have not broken that code yet.

 

[superiorsat]

The tank insulation is probably not thick enough for the tank to get colder than 36 degrees without the coil freezing then Ice insulates the coil causing the warming. I'm guessing you might be stuck at 36 as your lowest temp and just have to wait longer to get it carbonated.

 

[Rob2010SS]

The tank insulation is probably not thick enough for the tank to get colder than 36 degrees without the coil freezing then Ice insulates the coil causing the warming. I'm guessing you might be stuck at 36 as your lowest temp and just have to wait longer to get it carbonated.

That's kind of what I wondered as well. I've never opened the tank at that point to verify though.

 

[SanPancho]

sometimes stratification occurs at the extreme. its a huge pain to diagnose, very hard and sometimes impossible to correct. im unfamiliar with tiny tanks and cooling coils, so i cant offer much else but to say that freezing is definitely a possibility for regular jacketed tanks and for cooling coils.
one way to avoid it (although not a sure bet) is to do any "extra" crashing beyond your normal crash at a very slow rate, like 1F over 12 hours, or even a day. its not guaranteed, but i have seen it work to eek out another 2-3-4F in crash temp. worth a try on your next batch.

 

[TLaffey]

Having a weird phenomenon happen at the brewery. We are running 2 CF30's on a 1/2 HP penguin chiller with the glycol set to 28F. I can consistently maintain 36F on the crash. However, the minute I try to go lower than that on either tank, I end up with the tank getting WARMER and getting stuck at 37F.

I have both running currently with 40 gallons in each tank. For the past week, they've maintained 36F. Started carbonating one of them. After realizing that I can't get the PSI in the one tank high enough for the carbonation level I want (max 15 psi) I figured, OK, we'll try and cool it down a bit more to try and achieve more CO2 absorption. So I set the inkbird to 34F. Within a couple hours, the temp on that tank jumped to 37.2F while the other tank maintained 36F. Even this morning, it's still sitting at 37.1 and the other one is at 36 still.

I've had this happen before and forgot that we can't try and chill below 36. What I can't figure out is the mechanics. Why is that happening? Perhaps with the chiller running through the coil in the CF for that long, it froze and is keeping the beer from going colder? If I wasn't canning tomorrow, I'd de-pressurize and open it up and see but I don't want to do that.

Thoughts?

Are you running the cold glycol into the bottom end of the coil? I believe that would maximize heat transfer and reduce the risk of icing.

I'm not sure what ABV you are working with, but that would also be a factor in how cold you can go. My quick google search (I can't find the table I'm thinking of) shows that 6.5% abv will freeze at 28*F.

Have you determined the duty cycle for the glycol running through the coils? A PID controller would reduce the duty cycle as the temp approaches the set point, so maybe that would help in the future.

 

[Rob2010SS]

Are you running the cold glycol into the bottom end of the coil? I believe that would maximize heat transfer and reduce the risk of icing.

I'm not sure what ABV you are working with, but that would also be a factor in how cold you can go. My quick google search (I can't find the table I'm thinking of) shows that 6.5% abv will freeze at 28*F.

Have you determined the duty cycle for the glycol running through the coils? A PID controller would reduce the duty cycle as the temp approaches the set point, so maybe that would help in the future.

Yes, the "in" line is the straight down line to get it to the bottom of the coil. Then the way out, it works it's way up the coil and back to the chiller. As far as the duty cycle, no, haven't done anything with that as of now. Possible idea for the future

 

[SanPancho]

Are you running the cold glycol into the bottom end of the coil? I believe that would maximize heat transfer and reduce the risk of icing.

i've never understood this. it makes no sense. granted, i was taught about jacketed tanks, so the whole coil thing is not something im familiar with but i'd think the principle is the same.

you cool the highest jacket that's submerged. this means the warmest beer- which is at the top- gets the coldest glycol. it cools, gets dense, and sinks. that's how you get convection and movement that equalizes temperature throughout the tank. its also the best heat transfer from a thermodynamics point as the deltaT is the highest. (especially important as stainless sucks isnt so great at heat transfer)

if you sent the coldest glycol to the very bottom, you're getting a much lower efficiency of heat transfer as the beer down there is already the coldest beer in the tank. and you're not getting any convection, so no movement to equalize temps in tank.

i dont get it. i've never understood this. i've seen thats the way those guys advise you do to it, but i just dont understand why this would work given the fact that cold sinks and warm floats. its totally counterintuitive vs the way cooling is typically arranged.

 

[Bobby_M]

i've never understood this. it makes no sense. granted, i was taught about jacketed tanks, so the whole coil thing is not something im familiar with but i'd think the principle is the same.

you cool the highest jacket that's submerged. this means the warmest beer- which is at the top- gets the coldest glycol. it cools, gets dense, and sinks. that's how you get convection and movement that equalizes temperature throughout the tank. its also the best heat transfer from a thermodynamics point as the deltaT is the highest. (especially important as stainless sucks isnt so great at heat transfer)

if you sent the coldest glycol to the very bottom, you're getting a much lower efficiency of heat transfer as the beer down there is already the coldest beer in the tank. and you're not getting any convection, so no movement to equalize temps in tank.

i dont get it. i've never understood this. i've seen thats the way those guys advise you do to it, but i just dont understand why this would work given the fact that cold sinks and warm floats. its totally counterintuitive vs the way cooling is typically arranged.

Due to the limited surface area of coil based cooling vs. jacketed, the same temp delta technique as counterflow and plate exchangers is employed. In counterflows, the coldest incoming water meets the coldest wort to maintain the maximum possible temp delta. In the case of Spike fermenters, 28F glycol meets the 36F beer at the bottom, warms up slightly and then encounters slightly warmer beer as it coils upwards.

 

[Brooothru]

sometimes stratification occurs at the extreme. its a huge pain to diagnose, very hard and sometimes impossible to correct. im unfamiliar with tiny tanks and cooling coils, so i cant offer much else but to say that freezing is definitely a possibility for regular jacketed tanks and for cooling coils.
one way to avoid it (although not a sure bet) is to do any "extra" crashing beyond your normal crash at a very slow rate, like 1F over 12 hours, or even a day. its not guaranteed, but i have seen it work to eek out another 2-3-4F in crash temp. worth a try on your next batch.

There's a FAQ on this topic somewhere in the Spike website that explains the stratification and temperature inversion that takes place. The simple solution is to reverse the inlet and outlet glycol lines to the fermenter (whether coils or jacketed) when the fermenter temperature reaches ~38F. The physics is simple though counter-intuitive. It works, but I still couldn't get beer temps much below about 33F with glycol temperature input at 28F.

In a practical sense, I suppose the extra -5F is useful but I seldom do it anymore. 36~38F is sufficient for my needs anyway, and avoids any 'beercicles' or unwanted freezing of condensation on the tank and glycol lines.

 

[Brooothru]

There's a FAQ on this topic somewhere in the Spike website that explains the stratification and temperature inversion that takes place. The simple solution is to reverse the inlet and outlet glycol lines to the fermenter (whether coils or jacketed) when the fermenter temperature reaches ~38F. The physics is simple though counter-intuitive. It works, but I still couldn't get beer temps much below about 33F with glycol temperature input at 28F.

In a practical sense, I suppose the extra -5F is useful but I seldom do it anymore. 36~38F is sufficient for my needs anyway, and avoids any 'beercicles' or unwanted freezing of condensation on the tank and glycol lines.

Here's the pertinent page:

TEMPERATURE INVERSION
At temperatures of 40F+ the beer inside your conical will have a standard temperature gradient with warmer on the top and cooler on the bottom. At around 40F this actually flips; a temperature inversion occurs. Due to density changes the colder beer will now be on the top and the warmer beer will be on the bottom.
To combat this our coil design has two configurations for cooling (refer to Figure 1) which will give the best results for either maintaining fermentation temps or cold crashing your beer.

• Temps of 40F+: You’ll want the ‘In’ line to be the top of the coil and the ‘Return’ line to be the end of the coil that bends straight
  vertical. This will keep the coldest fluid at the top where your beer is the warmest.
• Temps under 40F: You’ll want the ‘In’ line to be the coil run that goes straight to the bottom and the ‘Return’ line to be where
  the coil starts. This will keep the coldest fluid at the bottom where your beer is the warmest.

Figure 1
PRODUCT GUIDE
TC-100

in
return
return
in

~40F+
Under 40F

 

[SanPancho]

Due to the limited surface area of coil based cooling vs. jacketed, the same temp delta technique as counterflow and plate exchangers is employed. In counterflows, the coldest incoming water meets the coldest wort to maintain the maximum possible temp delta. In the case of Spike fermenters, 28F glycol meets the 36F beer at the bottom, warms up slightly and then encounters slightly warmer beer as it coils upwards.

Huh.
Counterintuitive. Inversion is a weird affect but answers alot of the "wont go below X temp" complaints. I guess at this size and with the limits of the design (coils) there just isnt a way to get decent convection going to stop it.

 

[shoengine]

Not to mention that your thermowell depth or orientation can make accurate readings before and after inversion difficult.