HERMs Stuck Sparge

[marker5a]

Hey All

I just setup a single tier three vessel HERMs setup using keggles and the hinged keggle false bottom from brewhardware.com and have been quite pleased with the setup in general but have run into a snag during my first two sessions on it. Both recipes were IPA recipes with 2 row and a little bit of C40 milled at the brew store, and I shoot for about 1.3qt/lb mash thickness. I'm not currently using hulls but just bought some for my next batch just in case (maybe first mistake on new system?). My process is generally as follows:

1.) Bring HLT and MLT to same temp and let PID stabilize to strike temperature (~160F) and mash in... stir the crap out of it.
2.) Second mistake - Immediately run circulation into HLT HERMs coil. I realize that this is not enough time for bed settling.

Right away, the thing got stuck and I couldn't pump anything out of the MLT. Removing the pump line and opening the ball valve also did not yield a single drop. I ended up stirring the mash again pretty aggressively to try and re-establish the bed and hopefully un-stick the valve. I waited about 20 minutes and opened up the ball valve... again not a drop. Did this a third time and got the same results again. I started to try and think of ways to really clear whatever was in there so I back fed the drain valve with water from the HLT and I could hear the blockage clear, saw bubbles, etc. From this point, I sealed off the drain of the MLT and kept the pump primed, and switched everything over to normal HERMs mode and was finally able to recirculate... minor victory. The beer ended up coming in way lower gravity wise than I had hoped and my volumes were all screwed up, so it's an IPA, but way off from the plan... oh well.

After finishing the brew session, I took everything apart, cleaned everything, and had a face palm moment when I realized the pickup dip tube in the MLT sits very close to the bottom face of the kettle (~30-40 mils probably), so now I'm pretty convinced that this may have been the main issue, although bed settling and possibly hulls could have really helped too.

My question is... what is a good gap to shoot for between the bottom of the dip tube and the bottom of the keggle. I know there isn't a rule for it, but would like some rough estimate. I don't want to start chopping the tube if there is something else I've maybe missed from above.

Thanks!
Chris

 

[Bobby_M]

You just want to cut the bottom of the diptube at a slight angle so that the lowest tip hits the bottom but retains an open space at the other side. Once you get that sorted out, remember that you need to throttle your recirculation (via a valve on the output of your pump OR a valve on the inlet of the HERMS coil to about 1-2 quarts per minute max.

 

[marker5a]

You just want to cut the bottom of the diptube at a slight angle so that the lowest tip hits the bottom but retains an open space at the other side. Once you get that sorted out, remember that you need to throttle your recirculation (via a valve on the output of your pump OR a valve on the inlet of the HERMS coil to about 1-2 quarts per minute max.

Hey Bobby, thanks for the input! I'll give that a whirl before the next batch and see how it goes.

As far as the throttle valve, I did realize late in the game how important the output valve was so I did add a valve on my pumps during the brew session, but I'm hoping the dip tube fix will solve a lot of the issues.

Thanks again for the quick reply and for all you do for the hobby! and happy Memorial Day!

 

[BrewboyTK]

I like to circulate pretty fast on my RIMS (1G/min). Occasionally the bed compacts. Anybody see downside to mixing a couple of pounds of grain with rice hulls in a bucket, hydrating the grist, and dumping into an empty mash tun. From there, put in another lb or two of hydrated grist on top, fill the mash tun with hot water, and mash in as normal?? Seems like a bottom layer with higher concentration of rice hulls would definitely help.

 

[day_trippr]

Greetings, @BrewboyTK, and welcome to the forums

There may be a simpler way than all of that.

I do ten gallon batches and when using a significant amount of wheat and/or oats (like more than 25% of the grist) I use between 1/2 and 1 pound of rice hulls (a full pound for my 50/50 barley/wheat recipes). I soak the hulls in a small bucket while I'm conditioning and milling the grains, then drain the hulls and spread them over my FB. Then I dump the grains on top, level them out, set my autosparge arm, and then underlet the mash tun with the strike volume.

A couple of minutes after the full strike volume has been added I give the mash one thorough stirring to equalize the temperature, put the lid on, wait five minutes, then start recirculating - slowly at first and building up to between 2 and 3 gpm. This has always worked - literally the only time I have had a truly stuck mash was when I forgot to add the hulls...

Cheers!

 

[BrewboyTK]

Your method seems almost identical to my method. . . .but easier!!

In all seriousness; thanks for the reply

 

[day_trippr]

I should note that I when I do that one stir I'm going all the way down to the FB and lifting as I work all the way around the tun. So I'm not really trying to keep the hulls on the bottom - I think they actually work best when they're mixed in well to keep the entire mash a bit looser, not just what's above the FB.

That said, I use a Blichmann stamped FB which having used both is more forgiving than a perforated FB, so outcomes may vary

Cheers!

 

[BrewboyTK]

Blichmann as well. Agreed, hulls all the way thru. Just thinking a higher concentration near the FB would be advantageous. I was aware of underletting but never researched it. Definitely going to try it. If nothing else good emergency procedure if/when grain bed compacts.

 

[Deadalus]

I have a union on my diptube and my FB folds. When assembling I tighten the union most of the way with the diptube against the bottom then lift the diptube up and tighten fully. One time I do remember it being too tight and working slow but that pissed me off enough to never do it again.

I do think my FB has a somewhat large hole size and seems to flow pretty good in general but I also liberally use rice hulls when I think there is potentially an issue for a stuck sparge like when using oats or raw barley.

 

[day_trippr]

If you do it right you'll never switch away from underletting. No dough balls, and flooding the grain from below forces the entrained air up and out so you have the best start to a low oxygen mash. But it does require one good stir to quickly equalize the temperature before letting it settle and then starting recirculation. That's when you'll realize there aren't any dough balls

Cheers!

 

[BrewboyTK]

Today’s the day!! BIG hazy IPA with oats and wheat!!

 

[TheMadKing]

I like to circulate pretty fast on my RIMS (1G/min). Occasionally the bed compacts. Anybody see downside to mixing a couple of pounds of grain with rice hulls in a bucket, hydrating the grist, and dumping into an empty mash tun. From there, put in another lb or two of hydrated grist on top, fill the mash tun with hot water, and mash in as normal?? Seems like a bottom layer with higher concentration of rice hulls would definitely help.

There's no benefit to recirculating fast. The lowest flow rate where you can maintain/ramp temps with your RIMS is ideal. Beyond that you're only adding problems without gaining any benefit

 

[TheMadKing]

Hey All

I just setup a single tier three vessel HERMs setup using keggles and the hinged keggle false bottom from brewhardware.com and have been quite pleased with the setup in general but have run into a snag during my first two sessions on it. Both recipes were IPA recipes with 2 row and a little bit of C40 milled at the brew store, and I shoot for about 1.3qt/lb mash thickness. I'm not currently using hulls but just bought some for my next batch just in case (maybe first mistake on new system?). My process is generally as follows:

1.) Bring HLT and MLT to same temp and let PID stabilize to strike temperature (~160F) and mash in... stir the crap out of it.
2.) Second mistake - Immediately run circulation into HLT HERMs coil. I realize that this is not enough time for bed settling.

Right away, the thing got stuck and I couldn't pump anything out of the MLT. Removing the pump line and opening the ball valve also did not yield a single drop. I ended up stirring the mash again pretty aggressively to try and re-establish the bed and hopefully un-stick the valve. I waited about 20 minutes and opened up the ball valve... again not a drop. Did this a third time and got the same results again. I started to try and think of ways to really clear whatever was in there so I back fed the drain valve with water from the HLT and I could hear the blockage clear, saw bubbles, etc. From this point, I sealed off the drain of the MLT and kept the pump primed, and switched everything over to normal HERMs mode and was finally able to recirculate... minor victory. The beer ended up coming in way lower gravity wise than I had hoped and my volumes were all screwed up, so it's an IPA, but way off from the plan... oh well.

After finishing the brew session, I took everything apart, cleaned everything, and had a face palm moment when I realized the pickup dip tube in the MLT sits very close to the bottom face of the kettle (~30-40 mils probably), so now I'm pretty convinced that this may have been the main issue, although bed settling and possibly hulls could have really helped too.

My question is... what is a good gap to shoot for between the bottom of the dip tube and the bottom of the keggle. I know there isn't a rule for it, but would like some rough estimate. I don't want to start chopping the tube if there is something else I've maybe missed from above.

Thanks!
Chris

Decrease your mash thickness to 2q/lb as well, that will help with your recirc

 

[BrewboyTK]

“I like” was a mis-statement. “Occasionally I need....”. Today for example: I tried underletting for the first time (worked awesome) but missed my 152F target. I was attempting an 8 G batch in my 10G mash tun so I had a lot of thermal mass given the size of my system. A faster recirc let me put a LOT more energy into my RIMS coil without inducing micro steam bubbles. As a result I could hit my target in 10m vs 30m.

 

[BrewboyTK]

Decrease your mash thickness to 2q/lb as well, that will help with your recirc

I hear that a lot; can I push you on that?? Assuming we don't have a porridge like consistency. . . . at some point, doesn't the mash "thickness" become irrelevant?? I usually mash in at around 1.5Q/lb. As I let the grain bed settle I inevitably get some clear (i.e. grain free) wort at the top; typically 1/2" to 2". Doesn't the mash thickness just determine the depth of that clear wort on top. . . . the grain bed depth will be the same.

 

[TheMadKing]

I hear that a lot; can I push you on that?? Assuming we don't have a porridge like consistency. . . . at some point, doesn't the mash "thickness" become irrelevant?? I usually mash in at around 1.5Q/lb. As I let the grain bed settle I inevitably get some clear (i.e. grain free) wort at the top; typically 1/2" to 2". Doesn't the mash thickness just determine the depth of that clear wort on top. . . . the grain bed depth will be the same.

That's entirely a function of your system, and your true mash thickness accounting for hoses, dead space under the false bottom, etc. It is also affected by grist composition, size of your crush, and your recirculation rate.

So while 1.5q/lb works for you, it might not work for everyone.

2qt/lb is a reasonable mash thickness that should work on most systems unless they have a ridiculous amount of dead space. So you're right, I should rephrase and say "mash thin enough that you have standing wort over your grain bed."

In terms of beer character, mash thickness is pretty irrelevant, as demonstrated by the success of BIAB. So why mash thicker than you need to. IMO it's better to err on the side of a thinner mash than to mash as thick as your system can take.

 

[BrewboyTK]

Agree completely. Do everything to allow the grain bed to settle as gently as possible (ie maximizing permeability) and make sure after it does settle, there is still some standing wort over it.

thx for the post.

 

[marker5a]

Decrease your mash thickness to 2q/lb as well, that will help with your recirc

Hey MadKing, thanks for the info! Yeah, was considering that as well, but going to try and eliminate the dip tube first as the cuplrit... then after that will be mash thickness.

In any case, thanks for the feedback!

 

[marker5a]

You just want to cut the bottom of the diptube at a slight angle so that the lowest tip hits the bottom but retains an open space at the other side. Once you get that sorted out, remember that you need to throttle your recirculation (via a valve on the output of your pump OR a valve on the inlet of the HERMS coil to about 1-2 quarts per minute max.

Happy to report this did the trick.... Running it right now and things are running great! Thanks Bobby! Would've come to you first directly but didn't want to interfere with your daily operations! Thanks for your help dude!

 

[Dog House Brew]

If you do it right you'll never switch away from underletting. No dough balls, and flooding the grain from below forces the entrained air up and out so you have the best start to a low oxygen mash. But it does require one good stir to quickly equalize the temperature before letting it settle and then starting recirculation. That's when you'll realize there aren't any dough balls

Cheers!

So why does underletting make such a difference? I couldn't believe when I started underletting that there were zero dough balls. I guess it the slower absorption? Whatever it is, I'd never go back to the wet to dry dump and stir.

 

[day_trippr]

I honestly have no idea why, and I don't recall reading any explanation. You may be right about absorption being "slower", though I typically run my pump wide open when underletting and that's up around 6-7 gpm.

But clearly it works, does have the extra benefit of being LoDO-positive, and frankly on my rig with an autosparge it's much easier to underlet (I was actually doing it before it was cool )

Cheers!