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Vexing issue with brewhouse pump losing prime

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  • Vexing issue with brewhouse pump losing prime

    Hello All-

    I am brewing on a 10 bbl Premier Stainless PubTech brewhouse with a manifold system and a Top Line C-114 brewhouse pump.. The HLT is electric.

    I am doing a lot of double brews on this thing lately and the PubTech doesn't really like production brewing... (Go figure)

    I've managed to work out a system to have the HLT up to temp and the kettle cleaned out so I can get the second brew started about 30-45 minutes after the first knockout ends. This system does not have a hot/cold mixing valve on the inlet to the hydrator. Instead one gets the HLT to the correct temp (I use 168F) and it goes in straight

    Here's my issue: On the second mash in, I can't get the pump to keep a prime. I turn it on, adjust the VFD to where it normally is on the day's first brew and start the grain. After about a minute, the flow rate starts gradually decreasing. I normally start about 6 gpm. A minute in, it's at 5.90, then 5.8, then 5.6.... And lower and lower it goes. I stop the pump (and grain,) give it a second, start it up again, and the same thing happens after the first minute or so. It's driving me totally bonkers.

    I can see tiny bubbles in the sight glass, leading me to a working hypothesis that the newly heated water (from the previous knock out) has lots of gas breakout and this is causing the loss of prime. The kicker is that this is a *relatively* recent development. We are double brewing all the time now, but in the past I was able to occasionally double brew without this issue.

    Addition info: The pump has nice new seals in it. This problem predates the changing of the seal and o-ring. I was hoping that would alleviate the issue, but alas... Also, the pump does not sound like it's cavitating or laboring at all. The only thing (that appears to be) different is that the HLT water has not had all night to sit and de-gas.

    So, if you've read this far, does anyone have any ideas on how I can go about rectifying this issue? As I said, it's driving me bonkers. And it's only going to get worse as we grow (like mad!) and add on more and more double brews.

    Any advice would be *greatly* appreciated!

    Thanks and cheers- Mike

  • #2
    I saw this post the day I was changing the bad seal on my pump. I have the 10 bbl premier pubtech system, though I have butterfly valves all over, and no manifold. I am now having the same issues. Pump sounds great, just loses suction, or something. It only seems to happen on slower than 20 hz speeds, i.e. sparge, mash in, whirlpool - all the times you need the pump, pretty much. No difference if it is pumping wort or water. I am thinking it could be a bad /dried out/cracked gasket on the pump intake side sucking in air. I will be replacing all the lower level gaskets next week to see if it solves the problem. In the meantime, have you found any solutions?
    David

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    • #3
      shaft seal

      I'd bet 10 to 1 is the main shaft seal, our cart pump kept losing prime and what was happening is that it sucks air in through that seal that's worn, seems odd that a micron wide gap can allow air in but it did. We added a new seal and voila fixed.



      Originally posted by panadero View Post
      I saw this post the day I was changing the bad seal on my pump. I have the 10 bbl premier pubtech system, though I have butterfly valves all over, and no manifold. I am now having the same issues. Pump sounds great, just loses suction, or something. It only seems to happen on slower than 20 hz speeds, i.e. sparge, mash in, whirlpool - all the times you need the pump, pretty much. No difference if it is pumping wort or water. I am thinking it could be a bad /dried out/cracked gasket on the pump intake side sucking in air. I will be replacing all the lower level gaskets next week to see if it solves the problem. In the meantime, have you found any solutions?
      David

      Comment


      • #4
        If you're using the pump for moving wort, it's almost certainly the main seal. Fortunately, the C 114 pumps are one of the easiest pumps to replace a seal on. The problem is why the seal died. If you do not have a cold-water wash on the seal, it will not last. Our C 114 vorlauff pump ate its seal within a couple of weeks of use; since I added a wash for the seal, it's gone five years without a problem. Fortunately, again, it's very easy to add a cold-water wash to the external seal on the C 114. There should be a tapped hole, 1/2" NPT, on top of the shaft housing between the pump head and motor. Just bend a piece of 1/4" soft copper tubing so it sits just over the seal, figure out how to adapt it to that thread, (a 1/4" X 1/2" threaded bushing and JB Weld works quite well), and hook it up to a cold water supply. All it needs is a trickle.

        While you're at it, CPE Systems has a great tutorial on setting the spring pressure for that seal on their website. This should be a one-time process.
        Timm Turrentine

        Brewerywright,
        Terminal Gravity Brewing,
        Enterprise. Oregon.

        Comment


        • #5
          Gentlemen-

          I agree that Panadero's issue is most probably the pump seal. My original issue (up there ↑↑↑) has not abated. I did change out all the gaskets and check the tightness of all the tri-clamps upstream of the pump. The kicker with my initial issue is that it doesn't happen all the time. It only happens on mash-in of the second brew of the day.

          Timm: I've been considering adding a pump seal wash/drip. I was thinking of cutting a solenoid valve into a water line and having some sort of relay off the GS2-AC drive so that it opens whenever the pump is powered up. Is this how you have your seal wash set up? Or are you just manually opening a valve when you want the seal wetted?

          Cheers- Mike

          Comment


          • #6
            Mike--I like the idea of an automated seal-wash valve, but, no, we just use a ball valve and threaten to mutilate brewers who forget to use it.
            Timm Turrentine

            Brewerywright,
            Terminal Gravity Brewing,
            Enterprise. Oregon.

            Comment


            • #7
              Mike:

              I don't know how your BH is piped or what kind of mash hydrator you have but here is my 2 cents.

              If the problem happens only on mash-in are you sure it's a problem with the pump? You don't say how you eliminated other possible problems. I had the same problem starting out with my 20 hl PubTech and it was a clogged mash hydrator. Husks and other particles clog the small holes of the mash hydrator. Also the spray balls on BH and BK. This would explain why it happens only on the second brew and not the first. So if you haven't already done this:

              1. Take the mash hydrator off the BH and rinse the inside into a white bucket. This way you can see if stuff comes out. I got a lot and it doesn't take much to clog the holes. Actually I could see before rinsing that the holes were clogged: husks were sticking out of the holes.
              2. Next time during mash-in when you have this problem check if the pump works (I assume you already did this, but just in case) . I don't know how the piping is on your BH, but with my BH this is easy: close mash hydrator water valve and open spray ball valve (both on same pipe). If no water comes from spray ball or other tried outlets (for example recirc pipe) then the pump is the problem. If only the mash hydrator does not work then the problem is the mash hydrator.
              3. I solved the problem by installing a 6" sock screen gasket after the recirc pipe and before the spray ball, sparge sprinklers and mash hydrator. I also put one before the BK spray ball. It is easy to take them out after cleaning and rinse out the husks. I also use one when cleaning the HX to catch particles before they go into the HX. Got them from brewerygaskets.com.

              Comment


              • #8
                Originally posted by TGTimm View Post
                Mike--I like the idea of an automated seal-wash valve, but, no, we just use a ball valve and threaten to mutilate brewers who forget to use it.
                Yeah, electrical is not my forte. I believe that it is an option on Premier systems. I plan on talking to them in Portland to see if they have something that may be retrofitted.

                Cheers- Mike

                Comment


                • #9
                  Thanks TAJ.

                  I did look into the hydrator as the culprit but all was squeaky clean in there.

                  The more I think/learn/ponder, I think the pump seal is a contributing factor. It's just soooo weird that the second brew of a double is the only time it manifests itself. I haven't noticed any other signs of a shot seal, this issue predates my last seal change, and a new seal didn't alleviate the issue. One thing that has been (sort of) working is that on the second brews I've been setting the pump speed higher and throttling back the valve at the hydrator. It doesn't work 100% but it's better. This is what leads me back to suspecting the pump seal, but the fact that it works perfectly on the first brew with the pump set lower continues to have me vexed...

                  The screen sock triclamp gaskets are a good idea. I may pick some of just for 'cuz.

                  Thanks again guys- Mike

                  Comment


                  • #10
                    Same issue

                    Hi Mike,

                    I have the same brewhouse with the exact same issue. Drives me mad. I have replaced all the pump seals and no luck.

                    I'll keep you updated when I find something.

                    Cheers

                    Comment


                    • #11
                      Mike, could you please check the following:

                      1) Make sure all your valves and gaskets are properly seated on all the joints on the lower manifold.
                      2) Is your Manifold Water switch on during mashing in? I've found that water will siphon from your CLT into the manifold when this solenoid valve is open. I can only assume the pump will draw air from here when your CLT is half full.
                      3) Make sure your whole manifold is purged with water prior to mashing in.

                      When I started at this brewery, we only did single 10BBL batches and this issue would occur about halfway through the mash in. When we started doing 2 x 10BBL batches, this issue would occur more likely during the second mashing in. I don't know why!!

                      For some mysterious reason this issue disappeared for several months, only to reappear a couple of brews ago and then disappear again. The only thing I could think of was that I was tightening the tri-clover clamps prior to the second mash in.

                      I'll keep my eyes on it and let you know as soon as I know more.

                      Cheers

                      Comment


                      • #12
                        There are lots of pump information here: http://www.probrewer.com/library/pumps/

                        I am also checking with PSS in San Diego to see if I can find a couple of solutions to implement.

                        Cheers
                        Last edited by TiminOz; 03-28-2015, 03:48 PM.

                        Comment


                        • #13
                          PSS does not think it is the pump. We think it's something to do with the HLT level with the second mash in. If the level is below the door, I'd like to have them open it up and see if it is drawing in air or something like that. It seems to be only a second brew issue, and only combitank. Are they all electric element HLT tanks or steam? That may also help narrow it down.

                          Cheers,
                          Tim

                          Comment


                          • #14
                            Hi Tim,

                            Our HLT is electric. As mentioned before, I have seen this issue happen on first brews. It does seem to happen more often on the second brew.

                            Regarding the level of the water in the HLT, I always start with the same amount of water, give or take a 100L, on the second brew.

                            I'll keep trouble shooting and let you know.

                            Cheers

                            Comment


                            • #15
                              Thanks for the feedback Johann. I will pass it on and and keep working on a solution.

                              Comment

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