Author Topic: question about rims tubes  (Read 407 times)

Offline copachino

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question about rims tubes
« on: January 21, 2022, 07:21:08 am »
hi all, im new to a tre vessel system, i just got a brewers hardware pilot system with 20 gallon kettle and a rims tube,
i just made my first brew, and i wasnt that good, i got around 50% efficiency and got stuck mashmany many times, all looked like the grain bed was compacted way too much, so maybe my flow was too high?, also i didnt buy the sparge arm, so im not sure if that may be a problem too

Offline KellerBrauer

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Re: question about rims tubes
« Reply #1 on: January 21, 2022, 07:47:17 am »
Im not real familiar with a RIMs system, but a couple things can cause a stuck mash. 1) if the bed gets compacted.  I like to keep the water about 1-1/2” above the grain bed.  2) the ratio of grain to husk in the mash.  Much of the ratio is based on a few factors as well.  For example, if you’re grain bill contains a lot of wheat.  Also, the grain crush can play a factor — how was it milled?
« Last Edit: January 21, 2022, 07:48:53 am by KellerBrauer »
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Offline ynotbrusum

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Re: question about rims tubes
« Reply #2 on: January 21, 2022, 07:53:53 am »
I am willing to bet that it was recirc rate - too high.  It should just maintain levels - equillobrate, essentially.  Some suggest stirring the top 1/3 of the mash every 10- 15 minutes.  Also, don't start the recirc right away - give it 10-15 minutes after dough in is complete and well stirred to begin.
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Offline BrewBama

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question about rims tubes
« Reply #3 on: January 21, 2022, 08:31:04 am »
As mentioned above, several factors at play here.  Whenever I change a major process I get lower efficiency for the first few batches. After some experience the efficiency rises back to an acceptable level.

Here are some ideas:

Efficiency: My MLT usage instructions says it is designed for .67 gal per min but says efficiency can be increased by slowing down the flow. As mentioned, another mfr recommends raking the top third of the grain bed every 15-20 minutes. Sometimes I rake, most of the time I don’t. I haven’t really noticed a difference but it’s supposed to prevent channeling.

Stuck recirculation: I use .5-.6 gpm to recirculate during the mash as monitored by a rotameter in the flow path. As flow slows, I reset the .6 gpm, it slows again, I reset again. After a few iterations of slow/reset, the grain bed compaction and differential pressure above and below the false bottom stabilizes.  The flow is steady thru the remainder of the mash.  A grain bag helps with flow and a manometer can be used to monitor differential pressure. I use a bag but not a manometer.

Mash thickness:  I like a thin-ish mash. I routinely use 2.x qt/lb liquor/grist ratio. I believe it assists in recirculation.

Crush: Milling your own grains at home will allow you to dial in the perfect crush for both your brewing system and the grain you’re using. When your grain is milled properly, you’ll move closer to achieving consistency and maximum brewing efficiency.

Grain is an agricultural product. It’s size and friability can vary each year depending on the yearly harvest and the maltster. Likewise, mill gap settings are not universal, and while there is not just one “ideal gap setting,” if you’re using a 2-roller homebrew mill, you can start with a gap setting of a credit card and adjust from there.

I use a 60/40 crush (60% remaining on top while 40% falls thru a No14 sieve).  But it took several iterations to get the balance I like between flow and efficiency. I started at 70/30, moved to 65/35, and landed on 60/40.  I could probably move to 55/45 but I’m ok. I doubt it’s a $2 difference in grain cost vs. a stuck recirculation potential I’m unwilling to risk. You’ll find your mill gap after a few brews.

RIMS:  I used to use a RIMS. I found there is a balance between flowing fast enough over the element so you don’t scorch the wort and a stuck sparge from flowing too fast.  Even though I brewed good beer with the RIMS, I switched to HERMS to eliminate this additional balancing act coupled with the fact that the wort doesn’t come in contact with the element.
« Last Edit: January 21, 2022, 10:25:30 am by BrewBama »

Offline mabrungard

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Re: question about rims tubes
« Reply #4 on: January 22, 2022, 08:27:52 am »
Undoubtedly, too high an initial flow rate that compressed the mash bed and made the flow rate then fall too low.  The other thing that can screw things up is not having a PID controller for the RIMS element or having the temperature probe located anywhere other than immediately downstream of the element.  That is a sure way to scorch the wort. 

The proper way to monitor flow for any recirculating mash system is to incorporate a Manometer into the mash tun so that it's measuring the head level at the bottom of the mash.  That head level shouldn't be dropped below the bottom of the tun.  I find that the permeability of a mash bed does change over time.  It's initially low and does become more permeable as the mash progresses.
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