« on: August 25, 2013, 10:17:30 AM »
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)
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.
Any insight is welcome!