I have a question that may be somewhat specific to my equipment, but will start polling a larger audience here first…
I have a Top Tier system and have been using it for over a year, I love it with one exception: I get stuck mashes nearly every time I use my March pump (model 815PL). I can’t be the only one experiencing this with the popularity of this system, so I hope someone can help! Here is my mash system:
20 gal Blichmann kettle with false bottom/screen (also from Blichmann)
Auto-sparge arm
Out valve is the 90 degree elbow as it came from the factory (I have no filter or tubing attached in the tun)
I have had no issues whatsoever with runoff and recirculating by hand with a Pyrex container, but that’s not why I got this system, I want the ability to have a RIMS: re-circ with the pump with heat on for mash out and step mashing. I have tried modifying my malt crush (husks remain intact after my crush), I also tried conditioning the malt with some water, and also have tried adding a generous amount of rice hulls. I do not use a lot of adjuncts like oats or wheat. I get stuck mashes with any style, including straightforward pale ales that only occupy 1/2 of the mash tun volume.
After much tinkering with every aspect I can think of, I think it is related to the strength of the pull from the pump. It will routinely create a vacuum effect and drop the fluid level in my sight glass (indicating negative pressure below the grain bed, then it gets compacted, then stuck. I tried manipulating the flow with a valve on the out flow end of the pump, too: doesn’t help.
Could it be the physics/mechanics of the way the wort is being pulled from the out valve in the kettle? The only thing i have left to try is create a copper arm to place in the bed of the kettle to more evenly collect my wort at runoff.
If your system flows fine on gravity, then Denny’s suggestion of a grant is a good solution.
I don’t have your system, but have encountered similar problems. Backing off the flow, even dramatically, I had a stuck mash every time. I have found that if I vorlauf the first couple of quarts or so by hand with a pitcher - no pump - I can pretty much avoid the problem. I have a very fine kettle screen on my mash tun, and it seems like the pump just draws down all the flour in solution and fouls things up. Once that’s slowly and carefully circulated to the top of the grain bed, it pulls just fine without creating the vacuum. I’m not trying to emulate a Rims for temp control, but have found that recirculating the 1st runnings for 5 or 10 minutes ups my efficiency by a couple points.
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I have a half barrel with a false bottom. If you really throttle the pump out let, less suction will be on the inlet. I useually have noproblem, except with rye beers. I have the kettle and a selfless ball valve to make a grant, but need to make the hole. I think the pocess could be speeded up with another burner adding heat for mashout and the Skaggs.
I don’t have a Top Tier stand, but I use all-Blichmann kettles, with Blichmann false bottoms, for my mash tun (15 or 20-gallon depending on the beer) and boil kettle. Also use a March pump for RIMS. I recirculate on a Blichmann burner, directly heating the mash tun.
For the first five or six batches, I had symptoms of a “stuck mash”, where the output of the pump back to the top of the mash would start to sputter and seize, then eventually crap out altogether, as if it was trying to draw more wort through than was getting through the false bottom.
More playing around has lead me to a different theory, i.e. that the flow rate was too slow (valve on the output of the pump was closed too much) and the burner was too high, which was allowing the wort underneath the false bottom to overheat and actually start boiling, which in turn allowed bubbles from the boil to get drawn into the pump causing it to seize and lose prime. Even when the burner flame is very low.
Opening the valve on the output of the pump (probably somewhere in the vicinity of 1/2 open), and keeping it there, has solved this problem completely. A higher rate of flow means that more wort is moving across the bottom of the kettle and does not get hot enough to start boiling, but not enough to clog up the false bottom. I let the pump run continuously at a constant and fairly healthy rate. The Blichmann false bottom can take a healthy flow of wort.
I wish I could see underneath the grain bed to see if this theory is accurate, but for me it explains what was happening, and the solution.
My note above was for the sparge, no flame. When doing fired steps and recirculating, yes, you want a fairly good flow, and I’m stirring often so that it does not set up.
Once at mash out I let the bed set, and Borlaug at a lower rate until clear.
After doughing in or any stirring thereafter, be sure to let things settle for 10 minutes before turning on the pump. When you do, start slow at first, then increase flow. The settling is key on my system (perforated false bottom in a kettle). In following that process, I have never had a stuck mash or sparge.
I use the Tower of Power with my Top Tier with Chugger pumps for recirculation. My system is sensitive to kettle heat and rate of flow which can result in a stuck mash. I find 1.25 gallons/minute to be the best flow for the Blichmann 20gallon kettle. I also needed to increase my mill gap quite a bit. Occasionally will still get sputters without full blown stuck mash.
I realize this is an old post, but maybe my fix will help someone else. I had the same problem, using a Blichmann 30 gallon based RIMS setup. I use mostly DIY components, except the kettles and the false bottom, which is the weakest link in my whole setup. MacGyvering a new false bottom now. Won’t use the Blichmann anymore. Always clogs when flakes are involved and sometimes when there aren’t.
Unfortunately the quick-connect couplers I use do not allow blowing back air through the hose. But I found disconnecting and reversing the flow from the pump works great, just a lot of hassle. With two extra 3-way valves and a bit of pipe screwed next to the pump on a board, all I now need to do is pull two handles, reversing the flow until it is unstuck, usually within 5 to 10 seconds, and then pull handles again to restart flow in correct direction.
Below is the schematic if anyone is interested:
Blue links are pipes, gray are hoses, dark circles are quick-connect points. Blue circle is pump, pie charts are valves showing open flow sides. Brown background is the board onto which all is screwed down.
Once I opened my mill gap slightly, began using a slightly thinner mash, and slowed my flow slightly, I no longer have any issues and actually gained mash and lauter efficiency.
Thanks for the links Thirsty Monk. Good info. To prevent is better than to cure I have played around in all kinds of ways with coarseness, and averaging around 89% efficiency. Will turn the coarseness up a good notch and see what happens. Keeping the flow reverser in the back pocket in case it still clogs up.
89% efficiency is pretty efficient - how much do you expect to gain? I hit the sweet spot (70-75% for me on a 60 minute mash, higher yet on slightly longer Hochkurz step mash times) on my system with a .040 mill gap and 400 micron mesh BIAB in a 20 gallon Infussion Mash Tun recirculating at about 2 clicks open on a butterfly valve (pump is a Topsflo DC). The manometer stays rock steady above and below the grain bed, so I have not encountered stuck sparge issues, even with flaked grains and wheat (but I am not opposed to rice hulls if the grist is heavy on those adjuncts).
Hi ynotbrusum, I’m not expecting to gain much efficiency if any at all. For me if I can just prevent stuck mashes and not change anything else I would be perfectly happy.
I do tend to mash closer to 120 minutes in various steps. I guess I could speed it up if and when I really need to. If the flow just goes, brew day is just relaxing, so not that eager to cut out more time.
I have played around in all kinds of ways with coarseness, and averaging around 89% efficiency. Will turn the coarseness up a good notch and see what happens. Keeping the flow reverser in the back pocket in case it still clogs up.