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  • Cooling Calculation

    Hello Probrewer guru's I have yet another cooling question....I recently contacted pro chiller to see what my cooling needs are and I was a little taken aback to say the least. They say we will need 15k+ btu's for our set up (6 7bbl fermenters and 1 - 7bbl brite). I am still working out an initial brew schedule to see how many fermenters will be in what stage of cooling so I can get a realistic btu number. I used the formulas here

    Weight of beer in gals. x 8.6( 1 gal water plus .avg terminal gravity) x Temp diff. / divded cooling time in hours. Weight x Temp Drop = BTU/hr Load
    BTU load divided by the length in hours too achieve temp drop provides the minimum BTU/hr duty.

    to make a spreadsheet for each process in our proposed set up. I you would like someone to down load it and apply it to their process. I don't want your numbers, just your feedback. We will probably end up going to go with the prochiller set up, but I am trying to find a less expensive alternative by finding out what our actual cooling needs are. The sheet can be found at the link below and it should be editable once it is downloaded. I really just want to know if I am way off the mark or if it needs tweaking. I know for us it will most likely be dependent on our brewing schedule. Thanks for any insight or suggestions.

    http://www.oddbbrewing.com/file-page.html
    Bill Walden
    Oddball Brewing Co.
    Suncook, NH

  • #2
    Refrigeration Loads

    Bill, if your numbers put into Pro's calculator are accurate, what is returned will be what you need.
    12,000 BTU is 1 ton of refrigeration. To give you a relative idea, the old school large window AC units are 18000 BTU systems or 1.5 tons.
    The chiller system is one of the most important things in your plant and also needs to be sized with repsect to the possibility that your production will increase. Its also an area that most start ups do not often think about redundancy on until its too late.
    There are many good threads on this subject.
    I personally would not want a single compressor system or a single chiller system in any Brewery because that leaves no backup.
    At the minimum end I would build the loop such that more capacity can be brought on line easily if and when its needed.
    Otherwise I'd go for a 2 stage unit if possible to start.
    Warren Turner
    Industrial Engineering Technician
    HVACR-Electrical Systems Specialist
    Moab Brewery
    The Thought Police are Attempting to Suppress Free Speech and Sugar coat everything. This is both Cowardice and Treason given to their own kind.

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    • #3
      Yeah I'm going with if Prochiller says you need that many BTUs, you need at least that many BTUs. And what about expansion? When those six 7bbls become eight, or get replaced with 15's? There's things to skimp on, glycol isn't one.
      Russell Everett
      Co-Founder / Head Brewer
      Bainbridge Island Brewing
      Bainbridge Island, WA

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      • #4
        load calcualtions

        Our load calculation numbers are going to be higher than a calculated daily average based on temperature drop, we try to anticipate the highest load condition your brewery will see during normal operation. The cooling load will fluctuate greatly depending on what is happening in the brewery, for example at the start of crash cooling, the cooling load is much higher than when your chiller system is maintaining temperatures in active fermentation or conditioning (but there is still a cooling load to hold tanks at temperature). The crash cooling load is small percentage of the brewing cycle, but the load or demand is there and you'll need the cooling capacity to service that load.

        Your spread sheet only covers the temperature drop cooling loads of the actual beer. When we run a load estimate we divide your cellar into three different categories; 35% in Active Fermentation, 30% in Crash Cooling (typically 68 F to 34 F in 24 hours), and 35% conditioning or holding at 34 F (percentages change based on customer, but this is our default). We then run three different sets of formulas for the three three different groups. These formulas factor in Temperature Drop vs cooling time (as you list below), but we also factor heat loss based on estimated ambient temperature (even insulated tanks will have some heat loss), we factor in the heat generated during fermentation, and we also include a safety factor to compensate for motor heat and line loss within the system, etc.

        I am not sure who on our team ran your cooling loads, but I inputted the data you listed and came up with about the same as what you listed- a little less- around 13,000 BTU/HR. Are you using city or well water for the Wort cooling load?

        So even if the average load pencils out to 5,500 BTU/HR, there will likely be times the cooling demand is much greater, and also times the cooling load is much less. Our goal with our load calculation is to make certain you have adequate cooling capacity when you need it.

        Hope this helps explain a bit more why our numbers may be higher than what you are factoring, if you have any questions- please give me a call.

        Good luck with your new brewery!

        Jim

        Pro Chiller Systems
        jimvgjr@prorefrigeration.com
        Last edited by jimvgjr; 11-20-2014, 02:51 PM.

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        • #5
          Thanks all

          Thanks gents, through this whole start up process we have been trying to find ways to save costs, I think I tend to stick in that mode longer than my partner. Sometimes I think to exclusion about finding work arounds rather than the what's best for the beer and I appreciate the kick in the shorts. I agree that temp control is a high priority system and shouldn't be skimped on. We will probably go with the recommendation we were given.

          Thanks Jim, I figured you ran your numbers differently and that I was missing something.
          Bill Walden
          Oddball Brewing Co.
          Suncook, NH

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          • #6
            On a related note, how would you estimate the cooling load required for holding a temperature on a tank? For example, lagering tanks.

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            • #7
              Originally posted by chinsi View Post
              On a related note, how would you estimate the cooling load required for holding a temperature on a tank? For example, lagering tanks.
              We use a formula that factors the temperature difference between the holding beer temperature versus the temperature of the room in which the lagering/conditioning vessels are located- also factoring for the insulation on the tank jacket.

              This load is very small in comparison to crash cooling or even active fermentation, for example we would estimate the holding load on a typical 30 bbl insulated Conditioning Beer tank holding at 34 F in an 80 F Cellar to be about 1,650 BTU/HR.

              I hope this is helpful, if you have a specific load scenario you'd like us to run through our load estimating program, please let us know or visit our website and and fill out the brewery load survey form. You will find the link for the survey here: https://prochiller.com/fermented-cra.../#craftbrewery

              Good luck,

              Jim
              Pro Chiller Systems

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              • #8
                There are places to skimp and save in a brewery, and places not to. Your chiller is definitely a place not to skimp. If anything, go bigger--as mentioned above, if you play your cards right, you'll be expanding in the future.

                I'll also second the suggestion of a 2-stage system. This allows you to run only 1 compressor when loads are light, and the second kicks in when needed. This not only saves electrical costs, but extends the life of the compressors by reducing short-cycling.

                We have two Prochillers--the one we started with, and the one we had to add when we expanded. The new one is a 2-stage, with the old one for extremely heavy loads and back-up.

                Remember that a loss of chilling can result in the loss of a lot of product. This is a place to think hard about redundancy. While a 2 stage chiller isn't fully redundant, it's better than a single compressor unit.

                On a related note: When we had only one chiller, it died on a Friday afternoon. Jim drove out here from Auburn, WA, on a Saturday morning and replaced the compressor for us. Since the cooling was down for such a brief time, and we were lucky in our schedule, we didn't lose any product. You don't get that kind of service everywhere.
                Timm Turrentine

                Brewerywright,
                Terminal Gravity Brewing,
                Enterprise. Oregon.

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                • #9
                  I am fully in the camp that you don't skimp on a chiller, and you don't want to err on the side of undersizing to save a few bucks.

                  That being said, in my experience with Pro (I love them and we're on our second chiller from them after having outgrown our first one, which was a workhorse for 4 years with no issues) I think they overestimate (at least in our case) the percentage of your tanks that will be in crash cooling at any given time, which ups the BTU numbers - maybe substantially since that seems to be where the biggest load would be.

                  I completely understand why they do it, and I'm not necessarily suggesting you ignore their recommendation, just relating our personal experience. We squeezed a lot of tanks onto our old 10 hp chiller beyond the BTU load they said it would handle (a testament to their equipment probably too!). And we're getting close to what they said our 40hp unit could handle, yet it always seems to be taking it easy, even in the heat of summer. Just my 2 cents, I'm not an engineer. I just think they are giving you somewhat of a worst case scenario, and in reality you may never approach that.

                  Glenn

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