Having trouble trying to mash a concentrated wort

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Jan 2, 2005
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Hi all,

For the second week straight, my attempts to brew a concentrated wort have failed miserably. Last week, my mistake was obvious. I followed Mosher's advice in Radical Brewing to multiply a 5-gal recipe by 1.4 for a 3-gallon boil, but I comically increased my water proportionately. So instead we just made 7 gallons of beer, did three boils, and spent 14 hours brewing. Good times.

Yesterday, though, having learned from my mistakes, I brought my water from 2.5 gallons up to 5 gallons and mashed with 16 lbs. of grain (some pale, some munich, and 2 lbs of crystal). The 2.5 gallons didn't even get all of my grain wet in my 50qt cooler / mash tun, so I doubled it early on, but my total water was well within 5gal batch limits, right? My wort's first running came out at 1.056, much lower than my anticipated 1.085. Fortunately I had the foresight this week to pick up some more stainless pots, and ran two 3-gallon boils on the stove simultaneously, total labor = 7 hours.

What am I doing wrong? I only got my mash temp to 143 deg. F for 60 minutes, if that has an effect. I don't think I'll try a concentrated wort again on my own, since simultaneous boils spaced 30 minutes apart seems to be working well for me, but when my friends get involved, we'll probably need to find a way (or buy more pots again).

Also, does anyone have advice for multi-pot boils? I'm surprised that I haven't heard much about this, since it seems to offer an excellent compromise between only being able to get about 3 gallons on a kitchen stove and the advantages of a full-boil. I tasted the batch we made last week as I racked it to a secondary, and I can't wait for it to be finished. It's going to be a huge beer. Is hop utilization linear with wort volume? Are there any other gotchas I should be mindful of? Spacing about 30 minutes apart is pretty effective with my single wort-chiller; that's about how long it takes to cool the first batch, rack it to the primary, and pitch the yeast, and then I'm ready to transfer the chiller and do it again.

Thanks for your input. I'll post again with results from these two batches.




Well-Known Member
Feb 8, 2005
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Pocatello, Idaho
As far as hop utilization is concerned, I think the primary factor is the gravity of the boil, regardless of volume. There is a good formula for predicting utilization based on the S.G. in Designing Great Beers, a must have book for anyone seeking to closely controll and predict the results of a recipe.

I often use a multi-pot boil, as I don't have a 7 gal stockpot, and have to boil on my kitchen stove. In the past, I have taken about 4 gals of first runnings into my primary pot (the one with a spigot in the bottom) and started that boiling while the grains in the tun are still flooded in sparge water. And about the time I see that initial runnings start to boil, I drain off the remaining wort on the grain bed, after it has rested for an additional 30 mins or so. This rest, which I have heard called "batch sparging" releases an extra boost of sugar, and increases mash efficiency. There is a thread on here somewhere that talks about batch sparging at some length. I am using a counterflow wort chiller, so I don't have to worry about transfering two separate batches of wort; I just run my first pot through it, then start adding the wort from my secondary pot to the first and continue till I have the volume I need. This whole process does complicate the issue of hopping, however, as you have to split the hops between two pots, with differing gravities (which could be helped a bit if you were to transfer portions of the two worts between pots, to even up the gravity). Hope this helps a bit!