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Multiple Chillers - set up as "backups?"

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  • Multiple Chillers - set up as "backups?"

    We currently run a 7.5 ton chiller that serves our needs well for about 90BBL of current capacity. We've purchased and are installed a 24 ton chiller for some future expansion, which will have head room for new tanks in the future.

    We can either keep the 7.5 ton running our existing 90bbl system and install the 24 ton for the new tanks (about 150bbl of expansion, but loads are very distributed).

    Is it possible to plumb them in series to service all of the tanks, assuming the flow is adequate? That way, if one chiller goes down, the other can support the load (or at least, partial load) while the other chiller is fixed?

    Thanks!

  • #2
    I am sure that the real chiller experts will chime in soon enough with better advice than mine, but thought you might find my experience useful.

    I have 2 chillers that run my fermenters, and they are plumbed in "parallel", not in "series." When I added a second chiller a few years ago, I initially had them plumbed in series, where chiller 1 feeds into chiller 2, and then chiller 2 feeds the fermenters. This did not work, chiller 1 was pumping 10 feet to get to chiller 2, and chiller 2 was pumping 100 feet through the lines to get back to chiller 1. So, there were balance issues and I had glycol pouring out of my overflowed chillers; one of the chillers overflowed while the system was running, the other one would overflow when it was off. Obviously, these are smaller, open bath chillers, sounds like you might be using some bigger, more pro-grade stuff than me.

    So, I then plumbed them in parallel, so both chillers go into and out of the loop independently. It still took a little balancing of flow with some partially closed manual ball valves, but it works well now. And we are able to isolate each chiller with manual ball valves in the loop so that one of the chillers can limp by while the other one is being repaired. In fact, I had a failed relay switch just 2 days ago, and was able to isolate the failing chiller for repair while the other one maintained temp, so this is fresh in my mind.

    Once again, there are better minds than mine out there, but as a hack plumber/brewer/electrician that scabs a lot of things together myself, this is possible.

    Good luck.

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    • #3
      If you have sealed reservoirs you can kill one pump and have the other run constant. As long as you dont over pressurize the smaller chillers hx you should be fine. Usually its not too hard to wire a vfd before the pump, especially one that takes external inputs like a digital pressure signal from your loops. Then it just adjusts itself to maintain a constant psi when multiple tanks are cycling on and off.

      But to be honest, theres such a big gap between 7 and 24 ton that im not sure its worth it. Is 24 the base load and 7 the boost? Or 7 the base and 24 the boost? Seems like youd get a lot of short cycling on the 24 in that scenario. Just a thought.

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      • #4
        System Configuration

        Originally posted by Nobl View Post
        We currently run a 7.5 ton chiller that serves our needs well for about 90BBL of current capacity. We've purchased and are installed a 24 ton chiller for some future expansion, which will have head room for new tanks in the future.

        We can either keep the 7.5 ton running our existing 90bbl system and install the 24 ton for the new tanks (about 150bbl of expansion, but loads are very distributed).

        Is it possible to plumb them in series to service all of the tanks, assuming the flow is adequate? That way, if one chiller goes down, the other can support the load (or at least, partial load) while the other chiller is fixed?

        Thanks!
        Are you saying you have a 90 BBL Brewhouse on 7.5 tons?
        That math does not work out. We have about 600 BBL of diversified FV load on 10 HP of refrigeration.
        Unless you are using modular Chillers on a large central well, the best way to set up redundancy is to parallel pipe and have it where one system can carry [some] of the load if one goes down. In this case you valve one unit off the line and bring the other one on. This is how its done.
        A real keen way to go if you have CLT is to use a dedicated machine for that section [CLT and Knockout] and possibly a little more on the loop depending on capacity, OR have a dedicated unit for Brite Beer tanks only. The idea is to get the knockout load off your main FV system, which if not setup correctly will also overload your machine, especially in the wrong hands. if you are undersized it creates all kind of issues with everything else you are attempting to coll down in a time frame.Knockout load does not mix well with anything if you have limited capacity.
        You do not want rigs with separate glycol wells and pumps running on the same loop at the same time. To do that correctly you need a common well that each chiller is ported to. Not package units.
        No redundancy on chillers, and especially a chiller with a single compressor is both lacking foresight and a bad idea for a facility that cannot " go down."
        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.

        Comment


        • #5
          I think there are probably two different good options.

          1. Use the 24 ton as your main unit, with its process pump feeding your glycol header. Then have the older smaller unit just pulling glycol from the new unit's tank, cooling it and returning it to the tank. You can set the temperature setpoint for the smaller unit higher than the main chiller's setpoint, so it only comes on when the main chiller isn't maintaining the glycol temp.

          2. Like Warren said, plump the smaller unit so it is only cooling your CLT. Here in Tennessee, in the summer, cooling our CLT water from 85 F to 38 F takes up more than half our chiller capacity.


          Originally posted by Nobl View Post
          We currently run a 7.5 ton chiller that serves our needs well for about 90BBL of current capacity. We've purchased and are installed a 24 ton chiller for some future expansion, which will have head room for new tanks in the future.

          We can either keep the 7.5 ton running our existing 90bbl system and install the 24 ton for the new tanks (about 150bbl of expansion, but loads are very distributed).

          Is it possible to plumb them in series to service all of the tanks, assuming the flow is adequate? That way, if one chiller goes down, the other can support the load (or at least, partial load) while the other chiller is fixed?

          Thanks!
          Linus Hall
          Yazoo Brewing
          Nashville, TN
          [url]www.yazoobrew.com[/url]

          Comment


          • #6
            We have three chiller units all feeding into/out of the same 300 gal. glycol back. The setpoints of the three units are staged, so the primary is set to 24F, the next to 26F and the back-up at 28F (not sure if those are the exact numbers). This works very well. Each chiller has its own pump that circulates the glycol to the back on demand, then there is a main process pump from the glycol back to the brewery plumbing. This pump runs continuously.
            Last edited by TGTimm; 02-13-2020, 02:22 PM.
            Timm Turrentine

            Brewerywright,
            Terminal Gravity Brewing,
            Enterprise. Oregon.

            Comment


            • #7
              Excellent

              Originally posted by TGTimm View Post
              We have three chiller units all feeding into/out of the same 300 gal. glycol back. The setpoints of the three units are staged, so the primary is set to 24F, the next to 26F and the back-up at 28F (not sure if those are the exact numbers). This works very well. Each chiller has it's own pump that circulates the glycol to the back on demand, then there is a main process pump from the glycol back to the brewery plumbing. This pump runs continuously.
              Timm, Precisely.....
              A Common Glycol well with multiple units is exactly what I was describing if you can build that way from the start. We have a 200 GAL central well that could be ported this way for additional capacity, along with 2 package units. So its a hybrid loop.
              The matter of having different smaller units that can be used to control different valve arrangements on a common loop is something that can evolve in less that perfect situations. It can however be made to work to some advantage within said capacity limits.
              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.

              Comment


              • #8
                +1 for common reservoir

                I've installed many redundant refrigeration systems. The best way I've found is to use the same size chillers and add to the number when you need expansion. Cheaper to stock spares, too! Pro Refrigeration sold me an indoor chiller unit designed for 2 remote compressor/condenser units. I rotate these into/out of use. Unit one on odd months, unit two on even months. Both can be used if we need massive refrigeration. Either can be valved out on the refrigerant side for repair/replacement. There is only one glycol pump that circulates through both brazed plate exchangers. Beware of adding pumps as that extra power must be paid for more than twice; once to push energy into glycol via the pump, and more than once for the equipment to now remove that heat energy.
                Phillip Kelm--Palau Brewing Company Manager--

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