efficiency, crush, low KO gravity.. help

[woohokie]

I've tried all the tricks I can think of and have searched for around here and can't seem to solve this issue. I seem to come up short on kettle full (and then KO) gravity. I've attributed it to different variables over the course of our 1yr of being open but lately I feel like I've done all I can to correct it. So for example:

We are a 7bbl setup, combo mash/lauter w/o a grant - more on that in a minute. So, the recipe I brew most often is simply 450lbs of GW Pale Ale malt and 25# dextrose. Mash is 1.25qt/lb using 141 gallons of water. First wort is 17.1P with mash ph checked after our 30min single infusion rest showing 5.35ph most often (sampled cooled to room temp and then checked). Iodine check looks normal etc. Kettle full gravity at 8.6bbls to boil down in 90 min to 8bbls is 13.8P w/sugar added to kettle full, and then knock out gravity is 15P - I.m looking for 15.8P which seems like it should be doable.

Our mashtun is the Stout/brewmation setup that recircs wort via a small centrifugal pump by pulling wort from the bottom outlet and sending it back through a RIMS tube which then exits out on top of the mash. The outlet of the pump can be throttled via a valve (but no VFD) which I use to gently recirc the strike water prior to adding grain. So, my process for mashing - all strike water gets sent to the tun, after which and before adding grain I start that wort recirc pump which is drawn from one side of a T connected to the only outlet of the tun and continue to run it during the entire mash in and mash rest. I do this BEFORE adding grain to (hopefully) possibly negate the issue of sucking down on the bed by starting the recirc pump AFTER I've fully doughed in. then I dough in 2-3 bags at a time, stir, 2-3 more bags, stir etc. until all the grain is in and I feel like its all mixed. I'm consistently nailing my mash rest temp of 147/148f. After the iodine, mash ph, and 1st wort check I then send the wort to the kettle via the other side of the T where a peristaltic pump is connected to. Lauter is always 1hr 45 min due to the peristaltic pumps fixed flow rate/speed - it's either on or off. During the lauter, I run off into the kettle and wait till the top of the grain bed is barely visible beneath the wort and then slowly trickly in sparge water to maintain no more than 1" of cover water, if that much. Also, every 10-15 min I re-stir and reconstitute the top 5-6" of the bed to fluff it back up and even it out (something I saw mentioned here to try). Also, I notice at slightly less than the kettle full volume I find that the mash temp probe generally reads ~164f which seems consistent across most batches.

At the end of the lauter last runnings have been consistently 4-5P which also says something is wrong. Crush has been checked with the #14 pan and sieve and it shows 70% on the sieve /30% in the pan. I've fashioned a grant from an SS stock pot and ferrules, and while it works I see no appreciable gains, and fighting to make sure it doesn't run dry or overflow isn't nearly as easy as my above method - however if I need to revisit it I while.

Also during grain out, I find pockets of what seems to be hydrated but still yellow/NOT gray spent grain that still tastes sweet, which says to me that sparge water isn't rinsing those sugars.

So, whats the deal here? Low kettle gravity and high last runnings leads me to believe that its channeling or bed compaction right? No?

Help... and thanks!

[jebzter]

My back of the napkin calculations shows about 82% mash efficiency, I am not sure how well others with the same equipment are doing. I would call around and see what others are getting. Your dough in seems adequate, though there may be some dough balls it sounds like, which could be on possible source of efficiency loss, but I would think your last runnings would be at a lower gravity if that were the case. Does your mash tun have multiple collection points that drop into a single outlet, or is there only one point where wort is drawn from the tun? This could be an issue due to only taking wort from one side of the tank. As for your boil off and gravities, if you are starting at 8.6 bbl and 13.8P, then if you hit 15P your remaining volume will be 8bbl, in order to hit 15.8P you would need to boil down to 7.5 bbl or add more grain/sugar. You could also try making your crush finer, every system is different in how it handles the mash, I know I dialed ours in by cranking it down until I saw an increase in runoff time. You don't need a grant necessarily, but a differential pressure gauge to see how much suction you are applying to the grain bed from below the false bottom will help you not compact the bed prematurely. We have this on our kettle and use a centrifugal pump to transfer, 10bbl run off is typically 45 min.

[woohokie]

Thanks for replying - my responses are below.

My back of the napkin calculations shows about 82% mash efficiency, I am not sure how well others with the same equipment are doing. I would call around and see what others are getting. Your dough in seems adequate, though there may be some dough balls it sounds like, which could be on possible source of efficiency loss, but I would think your last runnings would be at a lower gravity if that were the case. Does your
mash tun have multiple collection points that drop into a single outlet, or is there only one point where wort is drawn from the tun?

- the tun has one center cleanout/port,c so it's all coming from one center drain.

This could be an issue due to only taking wort from one side of the tank. As for your boil off and gravities, if you are starting at 8.6 bbl and 13.8P, then if you hit 15P your remaining volume will be 8bbl, in order to hit 15.8P you would need to boil down to 7.5 bbl or add more grain/sugar. You could also try making your crush finer, every system is different in how it handles the mash, I know I dialed ours in by cranking it down until I saw an increase in runoff time. You don't need a grant necessarily, but a differential pressure gauge to see how much suction you are applying to the grain bed from below the false bottom will help you not compact the bed prematurely.

- I've heard of these mentioned on here before. Any guidance on where to source one and how it would apply to my system would be great. Would it be something I could attach to a TC ferrule and install on the T? Or is it more complicated than that? What pressure should I be looking for or to avoid?

We have this on our kettle and use a centrifugal pump to transfer, 10bbl run off is typically 45 min.

[a10t2]

For starters, low-80s efficiency on a big beer isn't terrible. You may be getting some channeling due to the lack of a grant, and that's compounding the problem, but it sounds like the main issues are mash-in technique and under-sparging. By dumping grain directly into the hot liquor, you're getting dough balls, as you've seen. Applying continuous suction to the grain bed then causes the wort to bypass those areas of higher viscosity. It also forces you to mash in at a thinner ratio than would be optimal, as shown by the high tail runnings gravity.

I'd suggest:

• Figuring out a way to incorporate a grist hydrator for mash-in;
• Mashing in a little thicker;
• Giving the mash an actual rest, at least 15 min to let the grain bed find its own level;
• Once you get everything figured out, not disturbing the grain bed during lautering.

[jebzter]

Thanks for replying - my responses are below.

For a differential pressure gauge, you just need two sight gauges, both are open to atmosphere at the top, the one bottom goes below the false bottom, the other above, this way you have a visual reference of the negative pressure applied to the bottom of the grain bed. I try to keep the sight glass that is under the false bottom not more than 1 inch below the level in the other sight glass, for thicker mashes, this can go up to as much as 3", this corresponds to 1/8 PSI differential, which is very low. PM me your email, I will send you a picture of our set up. I do think the single port with no grist hydrator is causing and exacerbating your dough ball and efficiency issues. Your run off time is fairly long as well.