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Accounting for boilpot losses

yesterday I brewed what ended up to be 8 gallons of caribo slobber. I was trying to brew 10g. I used mash water 3.3 to come up with all the amounts of water to mash, water to sparge ect. I entered 1 gallon for the “boil pot loss”. After the “boil” and cooling the wort in a blichman 20g brew kettle equipped with the blichman hop blocker, I ended up with 2 gallons of stuff (wort filled with hopps) that couldn’t be sent to the fermentors. So does this mean I am going to have to increase the boil pot loss to 3gallon? If so how would that throw off my specific gravity? which by the way ended up at 1.06, where as the suggested sg for this recipe was 1.051. Is there any way to calculate if adding an extra 2g of water to boil would then hit the suggested sg of 1.051? thanks, Acbrews

If you know you lose 2 gallons of finished wort post boil, and you want to send 10 gallons to the fermentor, I would just put 12 gallons as the final volume and calculate accordingly. This will screw up some of your efficiency numbers, but if you enter those extra 2 gallons as if they’re boiled away then the worse situation will happen - your gravity will be screwed up.

(I suspect you’re using Beersmith - which I think is screwed up when it comes to your problem. But several people have tried to explain this problem on the Beersmith boards without success.)

The boil pot loss as you call it, is mostly protein with some amount of liquid. Only the liquid is carrying off some of your precious sugars. I think you might consider that half of the stuff at the bottom is wort. So if you left 2gal behind that means a gal of wort, so you need to increase your grain bill to account for that loss if you are shooting for a known volume of a know strength.

If you entered 1gal of loss, and got 2, but were still short 2gal (8 vs10), then something else was wrong with your calculations. Did you account for the liquid soaked up by the grain? Its 0.125gal/lb, so 10gal is going to grab 1.25gal that you won’t get back.

as I mentioned I used “mash water 3.3” not beer smith. This program does account for boil off which for an 18" diameter pot, which is 1.7 gal per hour, and it does account for the amount of water absored by the grain in the mash. the total amount of wort I sent to the boil kettle was 12.82 gallons, so with the 1.7g/hr boil loss, and the 2 gallons of wort that was full of sediment that couldn’t go to the fermentors, i ended up with about 8g to fermentors. So doesn’t it seem a little ridiculous to have to start the boil with 14.82 gallons to end up with 10gallons to the fermentor? or is that normal for other ag brewers? Given, the pot im using is a bit overkill for 10g batches.
Do the recipes from Ibrew master account for all these variables when they give you the recipe for a 10g batch?

I ran into a similar problem yesterday when brewing 5 gallons of Caribou Slobber as my first all grain batch. I ended up with exactly 4 gallons after boiling. However, I strain my wort before chilling to avoid clogging up my counterflow chiller.

I way underestimated the amount of boil off using my new 20 gallon pot. I figured there was no way Beersmith could be right, so I changed the numbers. OOps. Plus I boiled for a little longer than planned due to technical difficulties.

The gravity of the 4 gallons was high, so I ended up topping off the volume and the gravity was perfect.

There are three common sources of kettle losses:

  1. kettle geometry dead space
  2. Hop absorption
  3. Break material (coagulated proteins)
    You can measure the first one by draining water from your kettle, then measuring how much is left once your pickup tube stops draining. I’ve seen equations on this board to calculate the second based on how many ounces of hops you use and if they are whole or pellets. The third is dependent on what malt you use, how much of it, the pH of the water, how vigorous the boil, how quickly you cool, and probably many other factors as well. I’ve never seen an equation to figure that, but there must be some typical number you can use per pound of malt that would be close.

Only one other factor that you should be aware of. Kettle geometry is not additive with the other two; it is more like a minimum loss parameter. If Hops and break add up to less than what your kettle geometry dictates, just use kettle geometry. If they add up to more, just use them.

as I mentioned I used “mash water 3.3” not beer smith.<<<

Sorry I missed that.

So doesn’t it seem a little ridiculous to have to start the boil with 14.82 gallons to end up with 10gallons to the fermentor? or is that normal for other ag brewers?<<<

I lose about 1 gallon between hop absorption and kettle deadspace, so I plan my recipes for 6 gallons in order to get 5 gallons to the fermentor. I also boil off about 1.7 gallons per hour, and thus start my boils around 7.75 gallons.

I typically start off with 7 or 7.5 gallons for a 60 or 90 minute boil, and end up with 5.25 gallons in the fermentor and 5 gallons of finished beer. Less in the end for very hoppy beers, and less for beers that have a huge amount of break material, but I don’t worry about the exact amounts too much.

Do you top off at then end or just let it go?

Do you top off at then end or just let it go?[/quote]I generally don’t when I have a situation like that, as long as the gravity is close to what was anticipated. I’ll top off if my gravity is too high due to the lower volume, but that is usually the result of a water volume miscalculation. When I brew beers with a lot of hops I scale my recipe up by a half gallon to account for the hops absorbing more and leave it in the kettle.

“I ended up with 2 gallons of stuff (wort filled with hopps) that couldn’t be sent to the fermentors.”

In my estimation that’s 2 gallons of waste? I would recommend taking as much liquid over to your fermenter as possible, of course I don’t know the ins and outs of your system, but I always take every last drop. Not sure if you are leaving this behind because you think it will effect the final product? I have never noticed that it does. When I started out I would ferment in multiple vessels, having one with cold break and all the mess and one without, never detected a difference. What finally convinced me was when I did a light delicate lager, I let the cold break settle in the fermenter, then pulled the clean stuff off into another fermenter, I took that 3/4 gallon of trub and pitched yeast into it and got two 16oz. beers out of it that were identical to the rest of the batch. Again, there are many reasons you would leave the 2 gal’s behind, but taste shouldn’t be one. good luck and cheers!

Do you top off at then end or just let it go?[/quote]I generally don’t when I have a situation like that, as long as the gravity is close to what was anticipated. [/quote]
Same here. Most of my beers tend to be in the 1.040 to 1.060 OG range, and I’m pretty good at hitting the target within a point or two for that range. Higher gravity beers are more variable for me, probably because I don’t brew them often enought to dial the process in. The only time I’ll top up is if I’m brewing a very low gravity beer, and then I’ll sometimes make a concentrated boil to make the mash, sparge, hop utilization numbers easier to hit before watering it down at the end to hit the OG.

To be clear, I’m much more interested at hitting the OG, IBU and SRM numbers than I am in hitting the volume target.

Yea, although I underestimated the boil off and it messed up my gravity and volume and when I adjusted, both were right.

You might call it shameless, ghetto, or brackish, but I am not against straining some (sometimes most) of the hop/break “infested” wort at the bottom of the kettle, to collect as much wort as possible (especially if we’re talking 2 gallons!), using a sanitized fine-mesh wire strainer propped above my fermenter bucket when collecting from the kettle. I also often strain out some of the hot break during the boil to reduce the amount left after chilling. Hops in the fermenter aren’t terrible - I’m more concerned about the hot and cold break, but honestly, with temp controlled fermentation usually finishing pretty fast (7 - 15 days), I don’t notice off flavors. If I’m going to cold condition/bulk mature, it’s in a keg or secondary after primary fermentation so the beer doesn’t sit on trub very long anyway. YMMV depending on the recipe.

To find the exact amount of boil off loss for my system, I did a boil with water only in my pot for 60 minutes. After cooling I drained the pot just as I would during a normal session. This will not account for trub and hop absorption but it put me in the right direction.
I have found that I leave 1 gallon in my brew pot on a normal brewday. I set my promash software to brew 6.5 gallons so I send slightly more than 5 gallons to the fermenter.

As a carryover from my extract brewing, I strained my wort before chilling. I used to have problems with hops and hot break clogging up my CFC, so I started pouring from my large boil kettle into a strainer with cheese cloth over by smaller kettle with a valve. This stopped all my clogging and allowed my to not leave any wort in the brew pot. My trub is clear of hops for yeast harvesting, etc.

I strain my wort before chilling also (don’t want my plate chiller to clog - impossible to clean out if that happens). But I use a screen in my kettle so that there is no extra step involved

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