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  • Ted Briggs
    replied
    Two things to think about for effecient heat transfer:
    --slower is better- throttle back the out flow for longer contact time. Make sure you dont exceed the tanks psi rating though.
    --Less glycol is better- glycol keeps the water from freazing but reduces its heat transfer ablity.
    Ditto on the point of selective harvesting of yeast. Try to crop your yeast early in the cycle to get faster dropping yeast. Basicaly this is genetic manipulation by selection. Though fast dropping yeast will probably be less attenuative!.....

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  • aswissbrewer
    replied
    Post Script

    Originally posted by Alex T
    sometimes, depending on your parameters (glycol temp, jacket area, etc) you can over do it. recently i worked with some 200HL tanks and they were taking more than two days to get to 4 degC. i found that when we reduced the glycol flow to these tanks that the cooling was actually more effective - ended up getting from 22degC to 4degC in 24hrs (so there was some icing on the jackets causing lack of heat transfer).

    alex
    Been having a few problems with my cooling system lately. Amoung other things a solenoid burnt out on me. This is one that stays in the open position when no power is getting to it.

    This meant that the line was constantly open and subsequently when a thermostat on another tank cut in, coolant flowed through this solenoid as well. The tank was subject to constant but intermittent cooling.

    What I noticed is that the beer temperature sank at a higher rate than if I had "crashed". It seems that the on-off coolant flow was more efficient.

    Right on Alex T !

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  • jimvgjr
    replied
    Originally posted by aswissbrewer
    The compressor doesn't run all the time while I am cooling the tank and seems to handle the heat ok. So the problem must be tank side.
    This is definitely a good indicator, it could also be the result of lack of flow through the jacket- which would limit the amount of heat being exchanged.

    Originally posted by aswissbrewer
    As to the temperature of the gycol line - that's a little tricky to measure. I had to unscrew the lines and measure the temp as the glycol flowed into a bucket.
    This is always a challenge to get good temperature readings, it is best however to keep the piping connected. When you removed the outlet pipe and let the outlet flow into a bucket, you likely reduced the line restriction and saw a greater flow than if the outlet pipe was connected to the fermenter- therefore your data might not reflect your normal operating TD across this jacket. Does that make sense??

    There are inexpensive electric thermometers with small sensors that you can affix to the outside of the pipe, or the outside of the stainless fitting on our tank inlet and outlet (place some insulation on over these sensors). With a sensor on both sides of the jacket, you can monitor these temperatures at various times during the day to get a better idea of the TD across the jacket.

    Originally posted by aswissbrewer
    What I do notice, is that the temperature of the beer comes down slowly and then if I do cut the cooling off with the thermostat the beer continues to cool and "overshoots" so to say. Ice ?

    The tank thermometer is low down in the tank and I am also thinking that the settling yeast (some does settle) might be disguising the temperature a little? Possible ?
    Steve
    I am not sure on this one, guess you should make sure that your solenoid is shutting off.

    Good luck Steve!

    Jim

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  • Brew49411
    replied
    You need to check your gravity before you crash..... Don't just guess cause sometimes you'll get burned. When your within about 1 degree from your target crash that baby from 18 right to 4. Thats how I roll!

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  • aswissbrewer
    replied
    glycol temperature

    Thanks for the hints!
    The compressor doesn't run all the time while I am cooling the tank and seems to handle the heat ok. So the problem must be tank side.

    As to the temperature of the gycol line - that's a little tricky to measure. I had to unscrew the lines and measure the temp as the glycol flowed into a bucket. The glycol flows out with a good pressure so I guess it isn't blocked. In fact that's what made the whole process b----- tricky .

    Example temps as far as I can tell:
    Line into jacket temp: 2.5 - 3 C
    Line out of jacket 3.5 -4 C
    Glycol in chiller 1.0 - 1.5 C
    Beer temp 7 C

    I raised the gycol temp up over 0 C in order to rule out ice formation. (At least thats what I figured). No real difference.

    What I do notice, is that the temperature of the beer comes down slowly and then if I do cut the cooling off with the thermostat the beer continues to cool and "overshoots" so to say. Ice ?

    The tank thermometer is low down in the tank and I am also thinking that the settling yeast (some does settle) might be disguising the temperature a little? Possible ?

    Be glad to hear from you guys again.

    Steve

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  • jimvgjr
    replied
    Originally posted by Sir Brewsalot
    Any idea what the temp of the glycol pipes leading to the tank are like?

    I mean, if they aren't so cold, it's likely na issue w/ the chilling unit. If they are, it something on the tank side - maybe icing as described above, or even a clog in the line restricting the flow.

    Cheers,
    Scott

    Great points Scott, another thing to check is the Temperature Difference across your jacket; the glycol entering temperature vs. the glycol exiting temperature. If the TD is high, it means that you are exchanging heat. A low TD, could indicate that your jacket is iced up (or jacket is undersized), and not allowing enough heat to be exchanged.

    Is your chiller compressor running all the time, or does it remain off a majority of the time? If your compressor is not running a majority of the time, and your chiller isn't "calling" for cooling, it would indicate a heat exchange issue. If your chiller compressor runs constantly, yet your still not able to get the glycol temperature cold enough, it could be a mechanical issue with the compressor or perhaps the load is just too great for this compressor.

    Good luck,

    Jim
    Pro Refrigeration Inc.

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  • Sir Brewsalot
    replied
    Any idea what the temp of the glycol pipes leading to the tank are like?

    I mean, if they aren't so cold, it's likely na issue w/ the chilling unit. If they are, it something on the tank side - maybe icing as described above, or even a clog in the line restricting the flow.

    Cheers,
    Scott

    Leave a comment:


  • aswissbrewer
    replied
    crash cooling

    Well, I got my glycol and gave it the best I could. I'm almost embarrassed to report that I only managed to bring down the temperature at a little over 3 Deg C per day. From 16 C (60 F) to 4 C (40F) in around 3 days. Room temp is around 15 C (60F).

    Originally I mistakenly thought that the lower the glycol temp the faster it could cool. Well that's one more thing I've learnt in these forums.

    As for the other issues, - the cause of the flocculation problems. I have taken notice and am tipping the cropping procedure and the wort protein (new malt delivery) as the most likely causes, thanks guys. What stymied me was that everything worked well with another ale yeast. I still want to stick with the 1056 as I like the flavour and the attenuation so I'll try to work this out.

    Crash cooling
    I have the beer in what is essentially a conditioning tank. A horizontal 10 Hl tank , manufactured in Holland by DRU. These tanks are great for maintaining temperature but I suspect that they are not too good for "crashing". There are lots of these tanks in micros and brewpubs throughout europe. Anybody have experience with these or similar tanks?

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  • Alex T
    replied
    hi,

    sometimes, depending on your parameters (glycol temp, jacket area, etc) you can over do it. recently i worked with some 200HL tanks and they were taking more than two days to get to 4 degC. i found that when we reduced the glycol flow to these tanks that the cooling was actually more effective - ended up getting from 22degC to 4degC in 24hrs (so there was some icing on the jackets causing lack of heat transfer).

    in my experience you should be able to set your glycol temp to -3degC and leave it, just adjust your tank's glycol flowrate until you get the desired effect. it may take a few batches to work out which way to go (i.e. more cooling, less cooling).

    cheers,

    alex

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  • dick murton
    replied
    As already stated, set the glycol temperature and leave it. Most people seem to find around minus 3 to minus 5 C works OK. preferably keeping it closer to minus three if possible to reduce unnecessary energy use in the compressors. Suggest setting it at minus five for a few brews. If that works ok, try setting it to minus 3.5, run for a few weeks, and so on. Depending on environmental conditions, it might just be possible to have a winter and summer setting, but if the insulation is good, there will be so little variation that it is not worth messing about with the seasons.

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  • Sir Brewsalot
    replied
    My advice would be to set the chiller at a single temp - as high as your patience for chilling a batch will allow, and then forget it. Throttling the temp to match the load is too much thinking, and probably not what the unit was designed to do. I don't have a lot of tanks either, so I only operate the chiller when I'm looking to effect a change in tank temps. (Probably wasn't designed to do this either!) Temps don't creep up as much at this time of year when the whole damn place is cold!

    Echoing what Dick and Kugeman were getting at: Definitely aerate. Grow ALL the yeast population and then you can crop enough of just the hi-floc stuff for the next round.

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  • kugeman
    replied
    Is it possible that your flocculation problems are related to the manner in which you harvest your yeast? Are you pitching cone to cone, or are you collecting the yeast in a separate vessel (keg, bucket, etc...) and then repitching? What size are your tanks? How much yeast are you pitching?

    If you pitch cone to cone you may be harvesting some poorly flocculating yeast from the top of the yeast pile in your cone (in addition to the good healthy stuff which settles in the middle layer of the cone). After 2 or 3 repitches it's possible that you've encouraged your yeast to be non-flocculent by continuing to selectively harvest this way.

    I use whitelabs calif. ale yeast and this has happened to me before. Once it's happened there's not a whole lot you can do about it. Luckily I filter my beer so I'm able to remove the suspended yeast (it just makes filter day a PITA).

    Just a thought.

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  • aswissbrewer
    replied
    glycol temperature

    I'm filling my chiller with 25% glycol which will give me a freeze point of ca. minus 10 C or 14 F. My minimum set point will be minus 5 C or 23 F.

    I have a pretty small operation and don't have a lot of tanks. So there are between times when I don't have to have the glycol down this cold.
    Have I understood your advice correctly? When possible and reasonable it would be more efficient coolingwise to raise the glycol temperature.

    Further, when I have to "crash" I could speed things up if I stepped down the glycol temperature parallel to the beer temperature?
    For example:
    Beer 64 F glycol 40 F
    Beer 55 F glycol 32 F
    Beer 45 F glycol 23 F
    A sort of, chiller drag run? Maybe these tempertures are not the right ones but would stepping bring something when I'm trying to get the maximum out of limited horsepower?

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  • dick murton
    replied
    Re protein - the cold wort should be bright, OK, not as bright as filtered beer, but if you put a couple of alternating sheets of black and white paper together to make very sharp stripes, then these should remain sharp when you look through a couple of inches depth of the wort. The more blurred the edges, the more protein haze you have, and the more likely you are to have some sort of fermentation / yeast settling problem

    The warmer you keep your glycol, providing the temperaure out doesn't rech the same temperature as the beer, the more money you can save. As long as you are extracting all the heat you can with that surface area of glycol jacket, there is no point in over cooling. You also stand a greater risk of forming an ice layer on the beer side of the jacket - which will completely wreck heat transfer characteristics. Ice is a pretty good insulator in comparison to liquid

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  • RobZamites
    replied
    I've never tracked the cooling rate - I crash from 55F to 33F overnight though. Crashing happens in the fermenters, then the beer is moved to serving tanks for further conditioning. They're in a cooler at 36-38F.

    Rob

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