Glycol chiller dropping tank temperature too low.

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beervoid

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Hey all, I've got an Kegland Icemaster G40 with 0.7HP cooling power and a 30L reservoir hooked up to a jacketed FV 1BBL tank through a thermowell. Tank is insulated with neoprene.
The jacket holds approximately 27L of glycol. I've got my reservoir set at 28f/-2c with a glycol mixture of 30% glycol.

When I set the fermentation temperature on the tank to let's say 21c with a +/- 0.5c degrees difference.
When my tank hits 21.5c every time the pump kicks in the temperature drops to at least 19c.

Is this normal for such a setup? Are other people experiencing the same?
I've tried restricting the flow a little but so far I haven't found any significant difference.

If the internal is going up and down between 21.5c and 19c, it seems the average would be more like 20c. I thought with a glycol chiller and thermowell inside the fermenter one woulld have more precise control over the temperature inside.

Would be interested to hear how everyone else is experiencing this with a similar setup.

Cheers!
 

SanPancho

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you dont need your glycol at -2c. you need it set for about 15 degrees (F) lower than your target point. (dont know what that is in C). any more than that is just wasted energy and the differential is so large between glycol and your set temp that it often overcools.

for example, in F- if i want to ferment at 65F, i set glycol for 50F. when its time to crash, then you drop glycol to its min/lowest setting, say 20F, which should easily get you 35F, or even 30F.
 
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beervoid

beervoid

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you dont need your glycol at -2c. you need it set for about 15 degrees (F) lower than your target point. (dont know what that is in C). any more than that is just wasted energy and the differential is so large between glycol and your set temp that it often overcools.

for example, in F- if i want to ferment at 65F, i set glycol for 50F. when its time to crash, then you drop glycol to its min/lowest setting, say 20F, which should easily get you 35F, or even 30F.
Hi thanks! I've seen that many people use this as a solution. Also read someone that installed a delay on the pumps, so the pump would not pump too long.

A thing i'm concerned about is that I do not have access to inhibited glycol here, wouldn't raising the temperature on my glycol reservoir give me a higher risk of my glycol spoiling?
 

SanPancho

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glycol doesnt spoil. the inhibitors are to prevent rust forming on any iron/steel components, or corrosion on copper, etc. typically what happens to glycol is that in a typical homebrew type setup its in a container and its open to atmosphere, indoors. the water will evaporate and leave you with too high of a glycol ratio which lessens heat transfer ability and makes chiller work harder. you should check it maybe once or twice a year. no big deal. or cover/seal the reservoir somehow to avoid the problem all together.

the delay on the pumps might be something that works but its less effective than changing the temp setting of the bath. the problem is that you only need a temp diff of about 15F. but if you're at 25F glycol and a 68F temp target, you're at 43F diff. so once the controller stops the flow, you have a bunch of glycol sitting in your coils that is about 30F colder than it needs to be, which causes the wort to keep dropping. its essentially 3x the temp diff or thermal mass that you need. that "excess" has to equalize, so it keeps cooling the wort.

im not sure how a pump delay would solve that. if anything, you'd want it to stop short of temp so it doesnt overshoot. im probably not understanding it correctly. but im guessing that in terms of the simple physics involved, its easier to just adjust your glycol temp. also saves energy/money.
 
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beervoid

beervoid

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glycol doesnt spoil. the inhibitors are to prevent rust forming on any iron/steel components, or corrosion on copper, etc. typically what happens to glycol is that in a typical homebrew type setup its in a container and its open to atmosphere, indoors. the water will evaporate and leave you with too high of a glycol ratio which lessens heat transfer ability and makes chiller work harder. you should check it maybe once or twice a year. no big deal. or cover/seal the reservoir somehow to avoid the problem all together.

the delay on the pumps might be something that works but its less effective than changing the temp setting of the bath. the problem is that you only need a temp diff of about 15F. but if you're at 25F glycol and a 68F temp target, you're at 43F diff. so once the controller stops the flow, you have a bunch of glycol sitting in your coils that is about 30F colder than it needs to be, which causes the wort to keep dropping. its essentially 3x the temp diff or thermal mass that you need. that "excess" has to equalize, so it keeps cooling the wort.

im not sure how a pump delay would solve that. if anything, you'd want it to stop short of temp so it doesnt overshoot. im probably not understanding it correctly. but im guessing that in terms of the simple physics involved, its easier to just adjust your glycol temp. also saves energy/money.
That delay was to run the pump for only 12 seconds then shut off for a longer period.

Ok maybe I've been misreading but I thought there is bacteria and algae that feed on glycol as its a sugar.

Anyway I will set the reservoir higher for now and yes monitor the mixture.
Can one use the same refractometer as used to measure wort for checking glycol mixture?

Thanks!
 

SanPancho

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interesting. the principle works, but seems like you'd burn out your pump more often with way more start cycles. vs just running it less (setting set point a bit higher to account for overshooting/extra mass)

yes you can use same refractometer. if yours is set for brix then its fairly easy. if set for SG you have to do a little math. nothing too bad, you can probably just pull the info off google. you can also pull a liter out of the reservoir and weight it, compare it to what you'd expect to see for 1/3glycol and 2/3 water at whatever temp you have. more math tho.
 
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beervoid

beervoid

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interesting. the principle works, but seems like you'd burn out your pump more often with way more start cycles. vs just running it less (setting set point a bit higher to account for overshooting/extra mass)

yes you can use same refractometer. if yours is set for brix then its fairly easy. if set for SG you have to do a little math. nothing too bad, you can probably just pull the info off google. you can also pull a liter out of the reservoir and weight it, compare it to what you'd expect to see for 1/3glycol and 2/3 water at whatever temp you have. more math tho.
I think you misunderstood, the pump runs only very short then takes a long break before it would run again giving the tank time to find equilibrium.
Found in a thread here, I can look it up for you if you want.

Yes I have brix so easy.
 
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beervoid

beervoid

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Here is the post.
 

SanPancho

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yes, but what you are doing is essentially turning your pump on and off multiple times over say, 5 hours. this is opposed to running it once or twice for 2-3 minutes at a time over the same 5 hours. the start up cycle is the most strain on the pump motor, so by increasing the number of starts you wear out the pump more quickly.

the theory of it is sound. it will decrease the risk of overshooting. but it will wear your pump and relay more quickly. maybe not such a big deal on homebrew level, but the principle stands. and it still wastes energy and stresses the compressor more than necessary keeping glycol near freezing instead of near ferment temp. its just not necessary.
 

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Here is the post.
we recently used the same (i think) unit for a nano. put a cover over the open part of the reservoir, no evaporation. and setting the bath temp is super easy so we only lowered it to freeze temps when we needed to crash/carb/condition. compressor ran way less often. didnt have to mess with any control settings. although tanks were 2bbl ferms with traditional glycol jackets, not coils like in homebrew.

oddly i remember calling into support at morebeer about trying to change something, i ended up teaching them like 2 or 3 procedures on the unit that they didnt even know about in their documentation. crazy.

honestly, my advice is keep it simple. just adjust the temp as needed. such a simple solution, and with more benefits too.
 
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beervoid

beervoid

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we recently used the same (i think) unit for a nano. put a cover over the open part of the reservoir, no evaporation. and setting the bath temp is super easy so we only lowered it to freeze temps when we needed to crash/carb/condition. compressor ran way less often. didnt have to mess with any control settings. although tanks were 2bbl ferms with traditional glycol jackets, not coils like in homebrew.

oddly i remember calling into support at morebeer about trying to change something, i ended up teaching them like 2 or 3 procedures on the unit that they didnt even know about in their documentation. crazy.

honestly, my advice is keep it simple. just adjust the temp as needed. such a simple solution, and with more benefits too.
Thanks, I agree and will be testing with higher temps for now.

There is only a small opening in the corner where the coil goes into the reservoir.
What did you use to cover it?

Cheers
 

SanPancho

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Thanks, I agree and will be testing with higher temps for now.

There is only a small opening in the corner where the coil goes into the reservoir.
What did you use to cover it?

Cheers
might not be the same unit then. ours was the one that had 4 built in pumps. on that one there's a hinge on the top of the unit/box, and the back half of the top/lid lifts up to get access to reservoir. fairly large opening. i just threw some plastic over it.

doesnt really matter what you use, just as long as its synthetic- plastic, rubber, etc. hell, even aluminum foil will work. just dont want to use something organic that will rot and get moldy/scuzzy like a towel, carboard, sponge, etc.
 

superiorsat

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In a situation like having 2 fermenters in different phases like one fermenting and one crashing. I would imaging if you had the over shoot problem I would set the temp a little higher on the fermenting batch so the shut off point and over shoot cooling would stop at the actual fermentation point that you originally wanted. Just about to be in this situation so these posts made me think about this particular scenario.
 
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beervoid

beervoid

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might not be the same unit then. ours was the one that had 4 built in pumps. on that one there's a hinge on the top of the unit/box, and the back half of the top/lid lifts up to get access to reservoir. fairly large opening. i just threw some plastic over it.

doesnt really matter what you use, just as long as its synthetic- plastic, rubber, etc. hell, even aluminum foil will work. just dont want to use something organic that will rot and get moldy/scuzzy like a towel, carboard, sponge, etc.
Its the same unit bit maybe its updated? Icemaster G40.
How many tanks have you run on this unit?
Im planning for 4x 1bbl eventually, only crashing 1 at the same time.

In a situation like having 2 fermenters in different phases like one fermenting and one crashing. I would imaging if you had the over shoot problem I would set the temp a little higher on the fermenting batch so the shut off point and over shoot cooling would stop at the actual fermentation point that you originally wanted. Just about to be in this situation so these posts made me think about this particular scenario.
I would think with more load there would be less difference.
 

SanPancho

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i dont remember the name, just that it had 4 pumps. bought it probably 2-3 yrs ago. we ran 2-3 2bbl ferms, no more than 1 crashing at a time.

when it was time to crash a tank we'd drop bath to 20. then just go back up once the beer was crashed/carbed/packaged.
 
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beervoid

beervoid

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i dont remember the name, just that it had 4 pumps. bought it probably 2-3 yrs ago. we ran 2-3 2bbl ferms, no more than 1 crashing at a time.

when it was time to crash a tank we'd drop bath to 20. then just go back up once the beer was crashed/carbed/packaged.
Ok nice, that unit was also 0.7hp/520watt?
How big was the volume of the jackets?
 

SanPancho

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looked up the order, it was the "Max 4" icemaster. 3/8 hp compressor. if you've got 0.7hp you're way ahead of us.

i dont remember jacket volume. small tanks, maybe 1/2gal per jacket? dont really recall to be honest.
 

segallis

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When my tank hits 21.5c every time the pump kicks in the temperature drops to at least 19c.

Is this normal for such a setup? Are other people experiencing the same?
The thermal mass in the jacket at a much lower temp than the wort, as well as the time lag to the thermowell due to the large volume of wort will both contribute to overshoots. I had proposed an idea on another thread, but never got any feedback, pro or con - the idea is that you run the circulation pump continuously and simply control the temperature of the glycol reservoir. The benefit is that there are no overshoots and the wort temp will exactly track the reservoir temp (there willl be some temp cycling within the glycol, but that has a much lower thermal mass than the fermentor, so the fermentor will remain stable - and you don't even need anything close to a narrow +/- 0.5 degree window). Everything is slow and steady. When you want to crash, you crank down the glycol and run things as you had been.

The only con, is the lag and delta temp caused by the yeast itself. I typically just keep things 4 degrees cooler than I want the wort for the first couple of days, as this is the delta temp I have measured during the first 24 to 48 hours of active fermentation. One way to eliminate that temperature difference would be to use the thermowell in the fermentor to drive the chiller reservoir temp lower as needed due to yeast activity. I'm not saying to use the thermowell to cycle the chiller compressor, as that would casue overshoots again due to the time/temp lag. I'm saying use the thermowell to drive the setpoint of the chiller temp, but the PID controlling the chiller is still using the temp probe in the reservoir itself to maintain the chiller temp. The thermowell is essentially another lag term (super slow timeconstant) that removes the error caused by yeast activity. I plan to add this to my setup to eliminate my -4 degree compensation, but I need to replace my ebay controller with a homebrewed ESP controller that can have multiple probes as inputs.

I have done this with both an FTSs coil and water reservoir, as well as encasing my fermentor in a thermal box, and simply maintaining air temperature. The wort temperature reamines perfectly constant. Here is a plot, showing my chiller temp hysteresis of about 3 degrees F, while the wort remains constant.

-G
 

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SanPancho

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its easier to just set your reservoir to about 15F lower than your ferm temp. then the thermal mass of the glycol in the tank doesnt pull down the temp even after your pump stops.

also uses alot less energy and is easier on your chiller unit. lots of benefits. the only thing you have to do is reset it to 25F or whatever temp you use for crashing.
 
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