Author Topic: Stuck recirc in blichmann mash tun  (Read 1766 times)

Offline archer75

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Stuck recirc in blichmann mash tun
« on: April 07, 2013, 09:53:46 AM »
I got a 15gal blichmann boilermaker and false bottom to use as a mash tun.  Also a pump with a ball valve on it's output to control flow rate.  Two batches of beer with it and i'm getting stuck recirculations every time.  Didn't use wheat in either batch.  On the 2nd batch I tried a couple handfuls of rice hulls and that didn't help.
I've run recirculation at the recommended rate of 1gpm. I've tried it lower and higher but eventually the flow will slow and then stop completely.  I have to stir the grain up for awhile in order to get the recirculation moving again.

I have contacted my LHBS to see what they set their mill to as I was wondering if that could be the issue, their response:
Our gap is .037.  However, I say that with a long caveat: Our mill is a pro brewery-grade mill with two, dual-driven smooth rollers that are each 9" in diameter, unlike homebrew mills that have knurled rollers. Our mill more or less pops the barley out of the hull, leaving the hull pretty much whole. Most homebrew mills actually do some grinding and tearing of the hull, so setting them this close together won't yield the same results our do (OK, I'm assuming you're asking in order to set your own mill).

Any suggestions?

Offline Alewyfe

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Re: Stuck recirc in blichmann mash tun
« Reply #1 on: April 07, 2013, 10:55:37 AM »
My set up is nothing like yours, I'm using a cooler mash tun and screen, however, I have found that if I recirc a couple of quarts...very slowly...by hand before switching to the pump it helps a lot. It's like I have to clear the fine flour that initially is on the bottom and get it on top of the grain, where it seems to stay if I maintain a nice controlled pump rate. I have better control doing this at 1st by hand, then letting the pump prime, and at that point I can recirculate as long as I want provided I'm careful not to mix that flour back into the solution again.

If I grab a paddle and vigorously mix the mash, I have to do the same thing again before recirculating with the pump or it will stick on me. Just my work around, but it may help.
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Offline AleForce

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Re: Stuck recirc in blichmann mash tun
« Reply #2 on: April 07, 2013, 12:24:19 PM »
What is the size of your hoses that you are using for your recirc?  Prior to switching to Blichmann kettles I was using 3/8" hoses, but had a similar problem. Switched out the 3/8" with 1/2" hoses and it made the difference.

When is the stuck recirc happening during the mash?
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Offline archer75

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Re: Stuck recirc in blichmann mash tun
« Reply #3 on: April 08, 2013, 09:30:32 AM »
All tubing is 1/2" silicon.  It recircs fine at first, maybe 5 minutes.  Then slows then just stops.  I stir it up and the cycle then repeats.  It tends to flow better near the end of the mash.

Offline bluesman

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Re: Stuck recirc in blichmann mash tun
« Reply #4 on: April 08, 2013, 09:54:19 AM »
It could be your crush. Post a pic of your crush (closeup). I have the same setup and find that rice hulls at a rate of 1lb/20lb grist helps the lauter. Also make sure you have a washer installed on the dip tube/false bottom.

The grist will compact to form a tighter filter bed as you pump through it over time. I use a flow rate of about 0.5gpm which is all you really need. As soon as the beer is clear, you will be ready to runoff/sparge. I typically vorlauf for 10-15min depending on the grist bill and volume.
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Offline bazowie

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Re: Stuck recirc in blichmann mash tun
« Reply #5 on: April 09, 2013, 03:31:39 PM »
Do you use just one ball valve, I use 2 ball valves and open the one on the tun fully and adjust the one on the pump for flow rate, and I too use rice hulls to loosen the mash up. To follow that up I am mashing 50 to 80 lbs of grain and not sticking.
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Online smkranz

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Re: Stuck recirc in blichmann mash tun
« Reply #6 on: April 09, 2013, 05:40:07 PM »
The first several batches in my 15-gallon BoilerMaker mash tun were also fubar.  Recirculation would start out fine, but eventually it would slow down, then the pump would start to pulse, and flow would eventually stop altogether.  If I was there to catch it, I could start it up again by opening the valve on the output of the pump, but it would just do it again.  I recirculate on a Blichmann burner, as low as I can get it without blowing out, and my un-scientific recollection is that it typically occurred while the heat was on trying to maintain or raise the mash temp. 

I surmise that the issue at least in part, was caused by a flow rate that was too slow, and wort underneath the false bottom that was starting to boil.  Bubbles from the boil would get trapped in the pump and cause it to seize.  Of course, I can't see what's going on underneath the false bottom, but that's my theory and I'm sticking to it  8).

Opening up the flow has solved the problem for the last five or six batches.  (I also replaced the impeller on my March 809 pump with the higher-flow impeller.)  More flow, less concentration of heat under the false bottom, no bubbles.  That false bottom can handle a substantial flow rate without clogging.
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Offline bluedog

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Re: Stuck recirc in blichmann mash tun
« Reply #7 on: April 09, 2013, 06:08:02 PM »
I also have a 15 gallon blichman kettle and run a RIMS with a March pump - 1/2" hightemp lines and 2 valves. The mash tun valve wide open, the outlet on the pump at about 1/4 open or less. I use 2 pint glasses of rice hulls for a 5 gallon batch and 4 glasses for wheat beers - double for 10 gallon batches. My crush is set at 0.036. I turn the pump on after the grain and water are in the mash tun and I close the outlet valve first anytime I stir up the grain bed - usually once after 15 minutes of recirculation and again at the 30 minute mark. For me rice hulls are cheap insurance and work well. It has been my experience that stirring up the entire grain bed while recirculating will compact the bed. 

Offline bluesman

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Re: Stuck recirc in blichmann mash tun
« Reply #8 on: April 10, 2013, 06:27:15 AM »
Do you use just one ball valve, I use 2 ball valves and open the one on the tun fully and adjust the one on the pump for flow rate, and I too use rice hulls to loosen the mash up. To follow that up I am mashing 50 to 80 lbs of grain and not sticking.

I control the flow the same way. Every now and then a husk will work it's way through the false bottom and get hung up in the ball valve, in which case I just open the valve on the pump all the way to push it out, then throttle the valve back to it's ideal position again.
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Offline archer75

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Re: Stuck recirc in blichmann mash tun
« Reply #9 on: April 10, 2013, 07:54:06 AM »
Do you use just one ball valve, I use 2 ball valves and open the one on the tun fully and adjust the one on the pump for flow rate, and I too use rice hulls to loosen the mash up. To follow that up I am mashing 50 to 80 lbs of grain and not sticking.

I have two.  The one on the kettle is left wide open and I only adjust the one on the pump.

I am getting some new grains from a different source to test the crush.  I'll be brewing again probably this coming monday. I'll also use more rice hulls than I did last time.

The other issue I have is i'm using the blichmann autosparge. Not for the actual sparging as the arm doesn't even reach the grain bed but rather for recirculation.  If the flow rate is too high it just needs up shoving aside the grain and creating a pocket of sorts with nothing but a clear site of liquid straight to the false bottom.
« Last Edit: April 10, 2013, 07:58:39 AM by archer75 »

Offline bazowie

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Re: Stuck recirc in blichmann mash tun
« Reply #10 on: April 12, 2013, 01:12:44 PM »
Do you use just one ball valve, I use 2 ball valves and open the one on the tun fully and adjust the one on the pump for flow rate, and I too use rice hulls to loosen the mash up. To follow that up I am mashing 50 to 80 lbs of grain and not sticking.

I have two.  The one on the kettle is left wide open and I only adjust the one on the pump.

I am getting some new grains from a different source to test the crush.  I'll be brewing again probably this coming monday. I'll also use more rice hulls than I did last time.

The other issue I have is i'm using the blichmann autosparge. Not for the actual sparging as the arm doesn't even reach the grain bed but rather for recirculation.  If the flow rate is too high it just needs up shoving aside the grain and creating a pocket of sorts with nothing but a clear site of liquid straight to the false bottom.

If you are not using that ball to regulate flow i would remove it completly until you need it. 1 pound of hulls is enough i used 2 pounds in 82 pounds of grain. I also crushed my grain at .047 on a Cereal Killer Mill, if you are crushing too fine that could be a problem.
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Offline troybinso

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Re: Stuck recirc in blichmann mash tun
« Reply #11 on: April 12, 2013, 05:08:04 PM »
I am surprised to hear these reports. Those Blichmann kettles look pretty bomb-proof, and I had considered getting one. I've never have to use rice hulls in my mash tun, and I have a pretty fine crush. I have used the abt false bottom for a keg kettle, and a homemade false bottom for a bigger kettle.

Offline archer75

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Re: Stuck recirc in blichmann mash tun
« Reply #12 on: April 15, 2013, 10:11:34 AM »
I brewed yesterday.  This time I weighed out the rice hulls and ended up using .5lb which was a lot more than I used last time.  I also got the grains from a different source so the crush wasn't as fine.  I had no problem recirculating.  Ran it at a pretty good flow rate without issue. 

Next i'm going to test again with grains from where I normally get them from but with more rice hulls and hope that fixes it.  The crush on their grains gives me excellent efficiency and they have some of the lowest prices anywhere so I really want to stick with them.