Calculations: Dual Boil Evaporation Rate - Home Brew Forums

 Home Brew Forums > Calculations: Dual Boil Evaporation Rate

12-12-2012, 06:29 AM   #1
JoshJoshua
Recipes

Mar 2012
Mesa, Arizona
Posts: 44
Liked 2 Times on 2 Posts

Im currently running a dual boil after I collect my runnings, and I feel like I'm missing my post boil volumes. If my batch is being split to ~3/gals a pot(x2 5gal pots) should I change my evaporation rate to double?

Right now in BeerSmith Im set at .5 gal/hr evaporation, but if I'm boiling in two pots should it be up'd to 1 gal/hr? I dont know, it might just be me and the numbers not playing out right in my head, but any insight into this would helpful.

Thanks

12-12-2012, 07:25 AM   #2
erikpete18
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Apr 2009
Seattle, WA
Posts: 830
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Your boil rate is going to partially depend on the size of your pots, so going from one bigger pot to two smaller pots would probably increase the boil off. I don't know that it would necessarily be twice as much, but its certainly something you're going to have to figure out. For now, figure out how far off you're batches are currently, and change the beersmith settings to reflect what its looking like. You might have to change it around a little bit after a few batches to dial in your system, but then you should be fairly good.

12-12-2012, 08:06 AM   #3
mattd2
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Sep 2009
Papamoa, New Zealand
Posts: 3,799
Liked 323 Times on 257 Posts

You should boil 3 gallons in each pot for an hour, the same way you would do your beer. Check how much has evaporated from each pot... that is you boil off rate for each pot.

12-12-2012, 02:12 PM   #4
Dave the Brewer

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Sep 2007
Nederland, TX
Posts: 253
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.5 gal/hr sounds like a mild boil in any pot to me, I would think with two pots you would be losing atleast 1 gal/hr. The best thing to do would be to do what Matt said and boil 3 gals of water in each pot for an hour as an experiment to find out your evaporation rate.
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12-12-2012, 03:01 PM   #5
Bobby_M
Vendor and Brewer

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Aug 2006
Whitehouse Station, NJ
Posts: 23,403
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If you're achieving a good rolling boil, I'd expect at least .75-1 gallons per hour per pot so start with about 3.5g per pot. Boiloff has a lot to do with wort surface area and yes, two 5g pots will have more surface than one 10g.
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