Flow rate issues for 55 gallon mash tun

I built a 55-gallon stainless steel brewing tree last month and successfully brewed my first half batch at the end of November. We are brewing a full 40-gallon batch this Sunday and would like some advice on our mash tun. Last time we brewed just a 20-gallon batch and it took 3 to 4 hours to collect the wort from the mash tun. I am worried about 3 main things with this and I am not sure if any of them are bad or not; is the grain going to soak for too long? Will the temperature loss over 4 hours cause problems? And we are just impatient and want to know if we can speed up the process.

Our setup is (2) 12” bazooka screens with SS pipe to a ball valve at the bottom of the barrel. When we first started to drain the wort after an hour soak we opened the 3/4" valve all the way and just let it flow as fast as possible, around the rate of 2 gallons per minute. After about the first 4 or 5 gallons the rate decreased quickly to a trickle. The rest of the time it flowed at a gallon every 15 minutes. I have read now that our flow rate was too high and we may have compacted the grain. This is an easy fix to reduce the rate to 1 gallon in 4 minutes with the ball valve, but the issue we have with that is it will take us over 3 hours to collect the wort on a 40 to 50 gallon batch if we can even get a proper flow rate of 1 gallon in 4 minutes. What are your thoughts?

We also placed the grain in the mash tun first then poured the hot water on top, this time I will reverse that to help prevent clogging and get a better grain bed. Let me know if you have any suggestions to prevent our system from clogging besides reducing the flow rate and adding the grains to the hot water. I appreciate your help!

*added note: we will be batch sparging for this brew day, but next time I might try fly sparging. I have not done a batch this large so we will see how it works.
I was told by another home brewer not to disturb the grain bed when adding the second addition of hot water after draining off the first running, on my previous batch I just added the second addition through a sparge arm. But everything I just read online recommends stirring in the second addition of hot water for a batch sparge. As noted below, that will be a little difficult with 100 lbs of grain, what do you recommend?

I would first try the two changes you have cited. I would think both will improve your lauter.

I would also think that you may be able to increase the flow over the first half hour while maintaining the stability of your grain bed. Batch sparge or no sparge, I am assuming?

As to temperature loss... my reading leads me to believe that the impact of that should not be significant, though I am not versed in batches of this scale. Alot of this thought was taken from discussions of overnight mashing.

I bet your lauter speed improves.

Luckily others far more experienced than I should be along soon. I am just avoiding some chainsaw work outside!

For me it takes about 2 hours to sparge (fly sparge) I can do it faster but I have no need to.

Are you batch sparging? I do fly on the big batches just because once you have a 150 pounds of grain settled in the bottom of the tun the last thing I want to do is try and mash paddle that thing. I also pump thru my flash boiler for about an hour to mashout and stop the conversion. So with that it's a 3 hour job after mash is done.

You may want to consider using a ss screen over a larger area. Our 55 gal drum for mashing used a screen originally made to fit the bottom of a sanke kettle. We got it to seat firmly against the bottom of the drum by using the copper pipe to apply some pressure down.

We could comfortably mash 100 lbs and fly sparge in 45-60 min.

You might also consider trying to condition your grain for better flow.

Pumping strike water into MLT
False bottom screen
100 lbs mashing

If the process does not become more efficient this time, I will definitely move towards a mash screen. I have only been brewing for a year and am still pretty new to all of this, how would I condition my grain for better flow?

Another possible fix....

Try using rice hulls. That's what we had to do in order to fix our stuck sparge problem's....should help yours out too.

malt conditioning

it leaves hulls more intact... rice hulls would be similiar, but conditioning is cheap!

Malt Conditioning:

https://www.homebrewtalk.com/wiki/index.php/Malt_Conditioning

Did this recently on a 50% 2-row/50% wheat mash and it worked great. No run-off issues at all. Cheaper than buying rice hulls.

Combine that with a mash screen and you should see improvement.

Did you say that this is a 55 gal brewing tree? I'd like to see some pics of that!

Holy SNIT!! "hours" to sparge???

Wow, I'm doing something really wrong then. I have a 30 gallon SS pot as a MT with a full sized false bottom and then under the false bottom is a good-sized copper manifold (just 'cause I had it).

I sparge in about seven minutes with a March pump. I cut back the flow rate a little bit with a ball valve, open the bottom of the MT and pump it out. Ten minutes tops and I'm done.

I would be really nervous about having grains sit that long. Wouldn't you start pulling a ton of tannins out of the grains with the wort sitting in the mash that long?

Cape Brewing said:

Holy SNIT!! "hours" to sparge???

Wow, I'm doing something really wrong then. I have a 30 gallon SS pot as a MT with a full sized false bottom and then under the false bottom is a good-sized copper manifold (just 'cause I had it).

I sparge in about seven minutes with a March pump. I cut back the flow rate a little bit with a ball valve, open the bottom of the MT and pump it out. Ten minutes tops and I'm done.

I would be really nervous about having grains sit that long. Wouldn't you start pulling a ton of tannins out of the grains with the wort sitting in the mash that long?

Click to expand...

Nope not at all as long as it's not to hot or to light on the gravity.
What kind of efficiency are you pulling draining that fast? I can't even drain my 10 gallon batches that fast. I'm pulling low 90% on a 150 pound grain bill.
At 4 minutes per gallon it will take a little over 3 hours to pull 47 gallons pre-boil. I boil off 6-8 gallons per hour.

Sweet Jesus.... those have to be some epic brew sessions. My efficiency is in the mid-80's and my suspicion there is that I have a really crappy sparge arm and I'm not getting "optimal" coverage from the top of the grain bed while circing through my heat exchanger.

I don't see how flow rate would determine efficiency. If I'm getting really good, uniform drainage throughout the entire grain bed, how would going really slow help?

I think the problem is just too small of an open area in the false bottom for how much mash you have. I have a FULL false bottom in my sanke tun and it sometimes sticks. The holes like to get plugged up with the grain that happens to get chopped in half, which makes a perfect round plug. I've pulled my false bottom out post mash and found up to half of the holes plugged up.

The other thing to think about is the siphon tube. Does the open end sit right on the bottom when the grain weight is on there? It should be slotted up the sides all the way around about 1/4".

On another note, the sparge rate shouldn't be a fixed volume but more relative to batch size. You don't think commercial 12BBL systems sparge at 1qt per minute do you? That rate is more in tune with 5-10 gallon batches. If it were me, I'd run out that 40 gallons in about an hour and keep raking the top 3" of the grainbed every 10 minutes.

Agree 100% with your comments Bobby... I think we have two different questions though...

1) CAN you run off that many gallons that quickly?
2) SHOULD you run off that many gallons that quickly... and why/why not?

Agreed... the full false bottom (and then I have a manifold too that sits under the FB) is a necessity to be ABLE to do it, but I've alway been under the impression that a mash sitting for that long, especially at sparge temps, would pull tannins. Plus... the efficiency question. I guess I'm not disagreeing with "greater efficiency at slower rates", I just don't understand it.

So, how long does it take Bud to sparge?
Gotta be days right?

3 hour sparge means something needs fixing

I think you SHOULD run it off that quickly so that you're not in the fricken garage for 4 hours longer than necessary because I honestly don't think a 4 hour sparge is going to be any more efficient than a 1 hour, assuming conversion has already occurred. You also don't want to be holding sparge water at temp for that long because it's energy wasteful. The question of whether or not you CAN is probably more an issue of crush, grist makeup (any wheat or rye in there? Rice hulls?) and certainly the separation medium is of concern which I brought up already.

I'm relatively sure that setups that exhibit great drops in efficiency with faster sparge rates already have a potential channeling issue that is made worse with a faster flow. The best lauter designs, specifically meant for fly sparging, should be able to run as quick as the set grainbed will allow without compaction.

In that specific tun, I'd be looking at either a full false bottom or a big copper slotted manifold.

Per usual, you said what I was thinking better than I could.

I just wanted to make sure I wasn't off in left field flying solo (which wouldn't shock me)

Cape Brewing said:

Per usual, you said what I was thinking better than I could.

I just wanted to make sure I wasn't off in left field flying solo (which wouldn't shock me)

Click to expand...

Your off in left field flying solo alright but you happened to run into Right Mountain on this one.

You
Wii
Bowling
Crying

Originally I did have a full screen for the bottom of my 55 gal drum for mashing, but getting a good seal around the edge to keep grain out was less than satisfactory. Wheeling and dealing allowed me to acquire something that worked out better and is easier to work with. I can collect 50 gal in an hour with very good efficiency. Malt conditioning lets me mash rye or wheat without sticking issues.

42 gal jacketed kettle with threaded coupler/ball valve drain.
Screen for sanke kettle fits the bottom contour perfectly.
Installed.
Mashing 90 lbs.

brewpal said:

but getting a good seal around the edge to keep grain out was less than satisfactory. .

Click to expand...

How 'bout using a silicon tube? I did that with my old MT. My false bottom was a hair too small for the pot so I took a silicon tube (heat/food safe from Northern Brewer), slit it along one side and slipped it around the false bottom so it acted like a gasket.

Worked perfectly.

And WOW... I'm surpised you can run off that quickly with such a small false bottom.

hey... if it works it works.

(nice set up btw)


And please Babalu... you have ZERO game (keep it on topic!!!!)

I would have tried the silicone tube gasket had I learned of it before getting this new kettle. Sounds it would have been just the ticket to seal the edge of a large false bottom against a less than perfect kettle bottom.

False bottom design is one of the bigger issues to master with grain bills approaching this size. The weight of the mash can really press down hard on anything flexible.

The mill used here is a non-adjustable schmidling malt mill which does a pretty good job of leaving husks intact. Malt conditioning helps even more when using rye or wheat. There is a fine line on the crush when going big. I can see how it would be easy to overdo it and get a sticking mash.

Everyone has given great input! Thanks for your help.
For the batch this Sunday I am going to add 5 lbs of rice hulls to my 96 lbs of grain and just take it slow. I do not have a mill, our Home Brewery store will crush it for free, but it might be worth the investment so I can condition my grain. If these methods do not work I will have to change to a false bottom. I like the one that brewpal showed us, thanks for the pics.

Did the SS mesh come pre-made in that form or did you have someone build it per your specifications? If so who built it and for about how much?

Also, can I condition my grains at all after they have been crushed and before I add them to my strike water? Or will I just have to have a grain mill to do so?

Identical to this one:

http://www.northernbrewer.com/brewing/brewing-equipment/all-grain-equipment/false-bottoms/abt-large-hole-false-bottom-1-2-hole-no-elbow.html

If I were doing giant batches one of the first thing I would want to have nailed down would be my crush.
Brewing batches of that size, a mill is a fairly small expense

I will admit I could pull it faster and I may not even lose % but I have not tried it yet. What would help a lot is a full false bottom. Right now I have a manifold in there which does give some dead spots a full false bottom over the manifold I think would fix any problem I may have and I have thought about making one.

But mainly I wanted to convey that it is ok to go that long, it wont hurt anything as long as you don't get it over 170* or the gravity under 1.010. I have done blonde ales like this with no tannins.

brewpal said:

Originally I did have a full screen for the bottom of my 55 gal drum for mashing, but getting a good seal around the edge to keep grain out was less than satisfactory. Wheeling and dealing allowed me to acquire something that worked out better and is easier to work with. I can collect 50 gal in an hour with very good efficiency. Malt conditioning lets me mash rye or wheat without sticking issues.

42 gal jacketed kettle with threaded coupler/ball valve drain.
Screen for sanke kettle fits the bottom contour perfectly.
Installed.
Mashing 90 lbs.

Click to expand...

Jesus god that's sweet...

Sorry, nothing constructive here. Just oogling the steel

Here's how we reinforced our SS braid.





Solid copper pipe with bunches of large holes drilled into it. Works like a champ. Just mashed 275lbs of grain (15% rye even) and ran off 100 gallons without a problem.

When I went to big batches (30-35 gallons), I had to back off on my crush. I also increased the size of my hose braid - about 36" of 3/4" OD SS hose braid. After making these changes, I had no problems until I made a 35 gallon batch of rye IPA (115 lbs mash). Even with the rye IPA mash, I still was getting about 0.5 gpm of flow.