Partial Mash vs. All Grain - 5 gallon pot

[Brownyard]

I've got a 5 gallon pot which I've been using for extract brews. I've been thinking of trying a 5-gallon partial mash/partial boil kit, but would I be better off just diving in and doing a 3 gallon full boil all grain BIAB? I cook inside on the stove, and don't want to buy a larger kettle, as I may eventually just buy an all-in-one unit.

Will a 5 gallon kettle be large enough for the average malt bill for a 3 gallon batch?

I've read about the mesh paint bags at the hardware store. Are they a good size for this, or too big?

Also, I have a 7.9 Spiedel fermenter. Are there any issues in fermenting a batch that small with that much headspace?

 

[3 Dawg Night]

I've done 5-gallon batches in an 8-gallon pot. It'll be fine, as long as you watch closely for boil-overs. Make sure to have a spray bottle of water/santizer and your spoon ready. Don't turn your back on it for a second!

For me, the cost of a bigger pot (I use a 10-gal now) was worth it for the peace of mind.

 

[Immocles]

I managed several 2.75G-3G brews inside of my old 5G kettle on the stovetop. I think most of my grain bills around the time were between 4.5-6pounds. I generally dunked the bag into about half a gallon to .75G of water as a sparge, and combined them for the boil. It can get pretty high in the kettle at the start of the boil, fyi. I brewed that way for about a year before being gifted a brewers edge mash and boil unit (7.5G volume kettle, have yet to brew a 5G batch on it, but have done a few full volume brews at about 4.25G with 10pound grain bills). All in ones are great!
Can't comment on the bag, as I use a wilser bag for all my brewing needs. I've got one for my 5G kettle, and one fitted for my M&B.
I also still ferment many 3G batches inside of a 6.5G big mouth bubbler. It works fine, but if you're adding anything to the beer ( dry hops, spices, etc etc), I advise against it. Its a ton of headspace for oxygen to invade when you open the fermenter to make those additions. If you find yourself hanging around the 3G volume range, I suggest a 3G siphonless fermonster.

 

[Brownyard]

Lots of good info there Immocles. Thanks!

 

[DBhomebrew]

With a 5G kettle and single cool water dunk sparge in a 5G bucket, I've been putting ~3.75G into the fermenter. Preboil volume is the limiting factor and I'm pushing the envelope at ~4.5G. If you're using gas and keep a close eye on it you should be fine. I keep a barely rolling boil in order to maximize post-boil volume. ~.3250gal/hr evaporation.

My usual beers are about ~1.045. With a very fine grind I'm getting a reliable 90% mash efficiency. With 5-6lbs of malt and mash/sparge volumes split to provide equal 1st and 2nd runnings, mash volume is not a limiting factor at all.

My biggest beer so far was 1.094 OG, 3.6G into the fermenter. Mash volume on that was getting a little iffy with 13.25lbs. Won't stop me from bumping it up a touch to try to hit the recipe's 1.097.

In short, use the kettle you've got.

 

[Brownyard]

With a 5G kettle and single cool water dunk sparge in a 5G bucket, I've been putting ~3.75G into the fermenter. Preboil volume is the limiting factor and I'm pushing the envelope at ~4.5G. If you're using gas and keep a close eye on it you should be fine. I keep a barely rolling boil in order to maximize post-boil volume. ~.3250gal/hr evaporation.

My usual beers are about ~1.045. With a very fine grind I'm getting a reliable 90% mash efficiency. With 5-6lbs of malt and mash/sparge volumes split to provide equal 1st and 2nd runnings, mash volume is not a limiting factor at all.

My biggest beer so far was 1.094 OG, 3.6G into the fermenter. Mash volume on that was getting a little iffy with 13.25lbs. Won't stop me from bumping it up a touch to try to hit the recipe's 1.097.

In short, use the kettle you've got.

Cool, thanks. Any details on "Dunk Sparging". I'm not familiar.

 

[DBhomebrew]

Cool, thanks. Any details on "Dunk Sparging". I'm not familiar.

It's a BIAB batch sparge.

My process for a BIAB with a single dunk:

Mash in kettle.
Pull and let drain into kettle, give a little squeeze. Flame on.
Dunk the drained bag into room temp sparge water in 5gal bucket. Open bag, give a mix.
Close bag, pull and let drain.
When the flow slows enough to not make a mess, I move the draining bag back over the kettle. Pour sparge water into kettle. Bag continues draining over the kettle until it runs 'dry'.

In this pic I've just finished the dunk and am letting it drain before moving the business back to the kettle.

Check out www.dennybrew.com for info on batch sparging. The only difference between batch sparging and a dunk sparge is whether you remove the wort from the grain or the grain from the wort.

 

[DBhomebrew]

When most people talk about BIAB, they are referring to a full-volume mash. All the water in the whole batch goes into the mash. This makes the mash volume the limiting factor in output volume.

By adding a sparge step, dunk or pour over, you're moving the limiting factor to the preboil volume.

With no sparge I was maxing out at 2.7G or so into the fermenter @~1.050. Adding the dunk increased my fermenter volume by ~30%. The difference would be even more with big beers.

You also get a bump in mash efficiency when you add a sparge step.

 

[Immocles]

When most people talk about BIAB, they are referring to a full-volume mash. All the water in the whole batch goes into the mash. This makes the mash volume the limiting factor in output volume.

By adding a sparge step, dunk or pour over, you're moving the limiting factor to the preboil volume.

With no sparge I was maxing out at 2.7G or so into the fermenter @~1.050. Adding the dunk increased my fermenter volume by ~30%. The difference would be even more with big beers.

You also get a bump in mash efficiency when you add a sparge step.

Hoisting the bag with that hook in the back of the cabinet was a clever move. I like it. Getting that volume out of a 5G kettle is impressive.
I did the same with my stovetop set up as far as a dunk sparge, especially when shooting higher gravity. I actually debate going back to it on my current set up, but haven't tried yet. I kinda miss that bump sometimes.

Off topic:
I notice you mentioned using a pretty low rolling boil, Do you ever have trouble with DMS in pilsner malts?

 

[DBhomebrew]

I notice you mentioned using a pretty low rolling boil, Do you ever have trouble with DMS in pilsner malts?

I've used exclusively Maris Otter thus far. But, in my reading leading up to my crossing the Channel soon, I'm not too concerned by it. At least one reputable source suggests a hard boil is excessive. One needs only to be sure the wort is moving well throughout the kettle, each molecule having it's turn at the surface.

 

[Immocles]

I've used exclusively Maris Otter thus far. But, in my reading leading up to my crossing the Channel soon, I'm not too concerned by it. At least one reputable source suggests a hard boil is excessive. One needs only to be sure the wort is moving well throughout the kettle, each molecule having it's turn at the surface.

I never had trouble with it on my stovetop, but I was boiling off closer to .75G/hr. I was just curious. Had a bit of bad luck on my new system the first time I used pilsner malt on it, and had narrowed it down to a weak/shortish boil.

 

[DBhomebrew]

I never had trouble with it on my stovetop, but I was boiling off closer to .75G/hr. I was just curious. Had a bit of bad luck on my new system the first time I used pilsner malt on it, and had narrowed it down to a weak/shortish boil.

https://www.homebrewtalk.com/threads/thoughts-on-boil-off-rate.674162/

 

[Brownyard]

With a 5G kettle and single cool water dunk sparge in a 5G bucket, I've been putting ~3.75G into the fermenter. Preboil volume is the limiting factor and I'm pushing the envelope at ~4.5G. If you're using gas and keep a close eye on it you should be fine. I keep a barely rolling boil in order to maximize post-boil volume. ~.3250gal/hr evaporation.

My usual beers are about ~1.045. With a very fine grind I'm getting a reliable 90% mash efficiency. With 5-6lbs of malt and mash/sparge volumes split to provide equal 1st and 2nd runnings, mash volume is not a limiting factor at all.

My biggest beer so far was 1.094 OG, 3.6G into the fermenter. Mash volume on that was getting a little iffy with 13.25lbs. Won't stop me from bumping it up a touch to try to hit the recipe's 1.097.

In short, use the kettle you've got.

You mention you're getting 3.75G into the fermenter. Are you gauging your recipe for that amount? Just wondering how much water you're sparging with and how much is in the dunk.

 

[DBhomebrew]

You mention you're getting 3.75G into the fermenter. Are you gauging your recipe for that amount? Just wondering how much water you're sparging with and how much is in the dunk.

Yep. I use BrewCipher as my workhorse recipe software and it figures everything based off Volume In Fermenter (VIF) as its target. It uses certain 'brewhouse' data to work everything out and while it starts with default settings you'll want to dial those in to match your system. For example, the common default for the amount of water lost to absorption in the grain is .12gal/lb. On my system, with my grind, etc, I lose only .088gal/lb. Any software needs this dialing in.

I'm now 16 batches into all-grain and have dialed my numbers in rather well. To do so, I use a stainless steel ruler to measure the height of the kettle contents at various stages in the brew day. Using metric (because it's just so much easier) I measure the height to nearest mm and plug that into the formula for the volume of a cylinder. My volumes are within an ounce or so and using them I've figured the rest of my brew house data.

Ok, back to your question of figuring strike/sparge volumes.

VIF is the target
VIF + kettle dead space = Post-boil Vol
Post-boil Vol + Boil off = Pre-boil Vol
Pre-boil Vol = 1st & 2nd Runnings

For best efficiency, you want the runnings to be roughly equal. 50:50, 40:60, 60:40, it's all good. In addition to the 1st run volume, the strike water volume includes the water lost to grain absorbtion.

So, for a recent brew:
90% Mash Efficiency
1.043 OG
3.72 VIF
4.82 Total Water
2.63 Strike (mash)
2.19 Sparge (dunk)
4.36 Pre-boil
4.07 Post-boil
2.1007 qt/lb mash ratio
5lb grain (+.25 non-mash invert sugar)
.0811 gal/lb loss to grain
.2897 gal/hr boil-off
.3456 kettle dead space

Note, these are all volumes at room temp. Due to thermal expansion, pre-boil was actually 4.53, just over an inch from the kettle edge.