Fly Sparging - A new invention?

Recently, I brewed my first all grain. My Dad was visiting his granddaughter and helped me out. I built a MLT (Mash Lauter Tun) with a Rubbermaid 10g , and we brewed a Quadruaple (or more) IPA. More on that later.

Anyway, while batch sparging, we were keeping sparge water at temp in a Rubbermaid 5g round cooler I just happened to have. That got us wondering. The insulation would make a great HLT (Hot Liquor Tank). So we began discussing possible designs of a gravity feed, sprinkler, etc. Which led to a discussion of the merits of batch sparging in terms of a time saver. Anyway, we went ahead with the batch sparge.

Until...my Dad and I, possibly under the influence of a homebrew or two, began looking at the two round coolers. My Dad, being the engineer that he is, and the finest M.E. I know of, couldn't stop building a Fly Sparge system in his head. So, while we brewed we discussed.

What we found out is that, while necessity is the mother of invention, so too, it seems was my IPA we were quaffing.

So, we begin with my MLT. A Rubbermaid 10G, with a 1/2" ball valve. Rather than using the standard Stainless Steel mesh hose, I modified a "Kettle Screen" to act as my filter. It is easily removed and, thus, cleaned. No stuck sparges so far. Works great.








The process:


I bring 5gals of water to a boil. Brewing is exactly like having a baby. The first thing you do, even if you don't know what you are doing is boil some water. Probably, your wife is going to scream at you too.

I transfer the very hot water (carefully) to the 10g MLT. This heats up the cooler, so the temperature loss when you mash is minimal.

Next, heat the strike water.



After the hot water has good 10 minute or so soak in the MLT, I transfer the hot water to the HLT - the 5 gal round cooler. At this point the water is around 190, and will be plenty hot to sparge in a little while (target sparge is around 175-185).

So here is the theory behind the HLT. While discussing a gravity feed system you have to really account for two big factors. 1) How to deliver the Sparge water safely and effectively, without creating a consistent flow that will deliver channels within your grain bed. (Why most fly systems have sprinklers). 2) We wanted to build a system that delivered sparge water at 12min/Gallon. We also wanted to collect wort at the same rate.

This is a very tricky engineering problem, which got my Dad and me very excited. We had found our Everest. Sure, batch sparging was working well, but we had to do this, because it was becoming apparent that it could be done.

So we noticed that the 5gal cooler (Now the HLT), almost fit inside the 10gal cooler (The MLT). But the spigot certainly would not fit. That is when we turned the HLT upside down. It fits perfectly.



So, to deliver the water, we drilled a few holes in the lid (which is hollow plastic, so no insulation to worry about). We drilled one 1/16" hole on the inside of the lid. The lid has two layers, so the first hole only penetrates one layer.



Then we drilled six 1/16" holes on the outside of the lid, in a circular pattern, with one in the middle. Same as the first hole, these holes only penetrate one layer.



When you turn the HLT upside down, and open the spigot, water enters the empty space in the lid through the inside hole and drips through the outside holes at 12mins/Gallon. This took a bit of trial and error, but one 'in' hole and six 'out' holes does the trick. 12mins/G on the nose.

So...back to the brew day....


We mashed in. (I drilled a 1/4" hole in the lid of the MLT, so I could drop in my digital thermometer lead. The timer is useful as well.)



Once the mash has done it's stuff (an hour at 152 in this case), I vourlofed the wort. This is simply re-filtering the wort through its own grain bed. Usually 3-4 pints worth does the trick. That is my friend Dr. Crowder lending his thoughts. Medical supervision, I suppose.



Next, I begin the runoff. After extensive testing, I found that opening the 1/2" ball joint exactly 7/64" of an inch, results in a 12m/G runoff. How do you measure that precisely? I used a 7/64" drill bit. Dead on every time.



...and just so I won't forget, I wrote it on my MLT.



I begin the runoff directly to the kettle. (Notice we are sampling a few commercial brews.)



Now I place my HLT on the MLT to begin the sparge. It fits like a glove, and really comes close to a closed system - insulating the grain bed and air space. The sparge water is very hot, so I'm wearing gloves (although very little leaks out.)

It is important to have a tight seal on the lid of the HLT. I usually just whack it on tightly with a rubber mallet.



And there is just enough room to drop in a digital thermometer lead to keep an eye on the temp of my grain bed.





Now begin the fly sparge. All you need to do is open the spigot release the vacuum and let gravity take care of the rest. I find that the same drill bit I used to measure the outflow works perfectly.



Does the drip create channels? Nope. First the incoming water is not a strong enough stream to create a channel through the 2" or so of water you should have covering your grain bed. If you are anal about it, (like me) just rotate the HLT 1-2" every five minutes or so. Absolutely no channels this way - basically a manual sprinkler arm.


Begin collecting wort to the kettle at 12m/G. At the beginning I usually hit the kettle with a little flame to raise the wort over 170 to stop conversion. I have a graduated stick, so I can tell how much wort I have collected.



To collect the 6.75G of wort I was looking for, it will take about 80 minutes. Just enough time to take a dip in the pool.



The remainder of the brew day is just like every other one: Boil, Chill and Pitch.

Here is my comparison of this method versus a batch sparge.

- Efficiency is slightly improved. I'm getting well above 75%.
- It is kind of cool to fly sparge. It's how the big boys do it.
- It just seems more relaxing. The runoff takes a little over an hour. There really isn't much to do here, so it is a great time to clean up and relax. With batch sparging, it seems like you are working a little harder and stressing a bit more. At least I was.
- Fly sparging does seem to add 15-30mins to my brew day. It is a trade off - the process seems a bit more relaxed to me. I like it!
- The wort I draw off is exceptionally clear!



A few tips I have discovered:
1) Above all else, trust the system. I find myself constantly thinking I have a stuck sparge. 12m/G is slow. It is running off. Leave it alone. RDWHAHB.

2) You can easily add additional sparge water to the HLT. Just have some on hand. To refill add another 2G or so after about 30mins.

3) As you draw off a few gallons of wort, put the spurs to the kettle and heat to 190 or so. Then kill the flame, the wort will hold above 170 and stop conversion.