Way too much boil off

[JoeSpartaNJ]

So today was the first run in my new 15 gallon brew kettle. I am still running my typical 5.5 gallon batches.

When I was done today, I only had 3.5 gallons make it into the fermentor. I also tried my friends bayou classic burner as opposed to my regular turkey fryer set up.

Same type of rolling boil and boiled for 70 minutes which I calculated for.

Would the increased kettle size cause this? Weather today is about 68 degrees, lower humidity and a bit windy if that helps.


Thanks,

Joe

 

[BBL_Brewer]

If the new kettle is of a larger diameter than the old one, that's your biggest culprit. More surface area = more boil off. Just use your new numbers on the next brew and you'll be gold. Even if you use your burner next time, use the same boil off you got this time and you should be real close.

 

[JoeSpartaNJ]

Thanks. Will fo


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[Snafu]

I typically boil off 1.5 gal/hr in my kettle.

 

[JoeSpartaNJ]

I boiled off at least 3 or more



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[Snafu]

Wow, even on the driest day, Ive never come close to that. I even use the blickmann burners.

 

[JoeSpartaNJ]

It wS also the first time I brewed out in the open. I usually boils at the entrance to my garage so it gets blocked from the wind somewhat


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[MikeInMKE]

All you boiled off is water. If you boiled off too much, add water to top off your BK to the desired post-boil volume. The still-hot wort will more than pasteurize the top-off water.

 

[VikingChrisColby]

I agree with Mike above, you can always add water in the last few minutes of the boil if you've boiled off too much. If you have a calibrated dipstick -- I use a long-handled plastic spoon with hash marks drawn on with a Sharpie -- you can see how your volume is at any point in the boil.


Chris Colby
Editor
http://beerandwinejournal.com/

 

[JoeSpartaNJ]

Wouldn't adding straight water at the end of the boil kill your OG numbers?


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[BBL_Brewer]

Wouldn't adding straight water at the end of the boil kill your OG numbers?


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No, not in this case. Since you boiled off too much, adding some back won't hurt anything. Since you were shooting for 5 gallons and only got 3.5, your OG was higher than anticipated. Adding back 1.5 gallons would have set things strait.

 

[JoeSpartaNJ]

No, not in this case. Since you boiled off too much, adding some back won't hurt anything. Since you were shooting for 5 gallons and only got 3.5, your OG was higher than anticipated. Adding back 1.5 gallons would have set things strait.

Is there a way to calculate what the estimated OG would have been if I had topped off?

My calculated OG for 5.25 gallons was 1.045. My measured OG for 3.5 gallons was 1.051.

 

[johngaltsmotor]

51(OG) * 3.5(gal) = X(OG) * 5.25(gal)

X = 34 so if you'd have stopped at 5.25 gallons (or diluted back to 5.25) your OG would have been 1.034

 

[JustLooking]

It's a direct proportion:
3.5 / 5.25 = .67
.67 x 51 = 34

so, if you had topped the 3.5 gallons to 5.25 your gravity would have been 1.034



edit:
too slow, that's what happens when you answer the phone while replying. :cross:

 

[JoeSpartaNJ]

Glad I didn't top off. That OG would have been too low.


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[JustLooking]

Yeah, but using the same proportion backwards:

51 / 45 = 1.13
1.13 x 3.5 = ~4

so, if you had topped your 3.5 gallons up to 4 gallons you would have hit your gravity.

 

[rlmiller10]

Wouldn't adding straight water at the end of the boil kill your OG numbers?


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If your target OG is calculated to 5 gallons and you boil to 3.5 gallons you should have been way over your target OG. example if you had a target OG of 50 points (1.050 OG) in 5 gallons that is 50X5 = 250 points. Those points of sugars were in there at the start of the boil (assuming no extract added during boil). They are in at the end but now 250/3.5 = 71.4 per gallon. So you should have had an OG of 1.071 with the 3.5 gallons. Topping up with water (0 points per gallon) would bring it back to the target OG.

 

[JoeSpartaNJ]

If your target OG is calculated to 5 gallons and you boil to 3.5 gallons you should have been way over your target OG. example if you had a target OG of 50 points (1.050 OG) in 5 gallons that is 50X5 = 250 points. Those points of sugars were in there at the start of the boil (assuming no extract added during boil). They are in at the end but now 250/3.5 = 71.4 per gallon. So you should have had an OG of 1.071 with the 3.5 gallons. Topping up with water (0 points per gallon) would bring it back to the target OG.

Maybe. Recipe calculated for 5.25 gallons @ 1.045 OG and measured OG was 1.051 @ 3.5 gallons. I know my efficiency tanked on this batch, but that is a conversation for another day.



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[MikeInMKE]

Glad I didn't top off. That OG would have been too low.

That's why I check gravity when I'm at my pre-boil volume (I may need to boil off excessive sparge water first, or add top-off water if I'm short) to get to my desired pre-boil volume, and then possibly add DME to get to my desired pre-boil gravity.

 

[JoeSpartaNJ]

This is the first time this has happened to me in 40 plus batches.

Lesson learned


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[Hopper5000]

You changed a lot of factors in your brew day so it's not surprising everything didn't go as planned. Yes a 15gal pot what is wide will boil off a lot more. I usually boil off about 3 gallons per hour if not a little more in my 15gal, outside, on a turkey fryer burner. No you know and you can adjust your recipe which would probably equate to a bit more strike and sparge water. Agreed with others that taking a pre-boil reading should give you a good idea of what your OG might be. However, kettle efficiency and brew house efficiency are a bit different so just be aware of that. Kettle tends to be higher.

 

[JoeSpartaNJ]

What calculators is everyone using for Mash and Sparge Calculations? I am a batch sparger.

I have been using http://www.copycalc.com/bob/BatchSparge and Sparge pal on my iphone. Both have been dead on until the last batch due to the variables.

For the next batch, I am going to change the evap rate from 10% to 25% and see how it goes.

 

[VikingChrisColby]

If you boiled enough that your wort volume was low, the wort in the kettle would have a higher specific gravity (SG) than your target (assuming you hit your numbers in the mash). Adding water to dilute the wort to your target wort volume would also lower the SG to your target OG.


Chris Colby
Editor
http://beerandwinejournal.com/

 

[JoeSpartaNJ]

If you boiled enough that your wort volume was low, the wort in the kettle would have a higher specific gravity (SG) than your target (assuming you hit your numbers in the mash). Adding water to dilute the wort to your target wort volume would also lower the SG to your target OG.


Chris Colby
Editor
http://beerandwinejournal.com/

There must have been efficiency issues as well considering my measured post boil OG was 1.051 @ 3.5 gallons when my calculated and expect post boil OG was 1.045.

All things to consider. I am going to brew a hefeweizen this weekend. I am going to change back to my original burner setup and boiling location. I am also going to estimate for at least 25% evaporation.

I am also going to make a volume measuring stick on friday night before brew day.

 

[VikingChrisColby]

Is it possible you collected less wort than you normally would have? That would explain both the volume and efficiency issues.


Chris Colby
Editor
http://beerandwinejournal.com/

 

[peterj]

I use the calculators on brewersfriend.com. I also measure boil off in gallons per hour. Using a percent evaporation isn't very accurate. The amount you boil off doesn't depend on the total volume, it goes at a constant rate. My boil off is about 1.5 gallons/hour. If I boil 6.5 gallons of wort for 1 hour I end up with 5 gallons which is 23% boil off. But if I boil 4 gallons for 1 hour I end up with 2.5 gallons which is 38% boil off. The amount boiled off is the same but the percentages are drastically different.

 

[helibrewer]

I always take a gravity reading before I start sparging. If my reading is in the low to mid 90% of this chart value, I know my conversion went fine:

Any issues downstream will due to lautering and/or boil off. For lautering you can use this chart to see what was left behind (as a percentage loss), just add cold water to the desired ratio and use that column of the chart:

 

[JoeSpartaNJ]

Is it possible you collected less wort than you normally would have? That would explain both the volume and efficiency issues.


Chris Colby
Editor
http://beerandwinejournal.com/

It's possible. Since I didnt measure actual kettle volume and being my first time with this kettle, I did not know what to expect.

 

[JoeSpartaNJ]

I use the calculators on brewersfriend.com. I also measure boil off in gallons per hour. Using a percent evaporation isn't very accurate. The amount you boil off doesn't depend on the total volume, it goes at a constant rate. My boil off is about 1.5 gallons/hour. If I boil 6.5 gallons of wort for 1 hour I end up with 5 gallons which is 23% boil off. But if I boil 4 gallons for 1 hour I end up with 2.5 gallons which is 38% boil off. The amount boiled off is the same but the percentages are drastically different.

While I could not measure accurately the boil off, It appeared from the volume I collected I had boiled off around 3 gallons. I usually end up with 6 gallons post boil and lose 1/2 gallon to kettle loss. I usualy have 5.5 gallons going into the fermentor.

 

[DrunkleJon]

I have found that I can drastically reduce boiloff (and save a lot of gas) by bumping down the gas on my burner to the point where I am still boiling but not super vigorously. I dont feel that you have to be on full blast the whole time, just enough to keep the wort moving seems to be enough and I have noticed zero difference in hop utilization or anything else.

 

[Clonefan94]

I use the calculators on brewersfriend.com. I also measure boil off in gallons per hour. Using a percent evaporation isn't very accurate. The amount you boil off doesn't depend on the total volume, it goes at a constant rate. My boil off is about 1.5 gallons/hour. If I boil 6.5 gallons of wort for 1 hour I end up with 5 gallons which is 23% boil off. But if I boil 4 gallons for 1 hour I end up with 2.5 gallons which is 38% boil off. The amount boiled off is the same but the percentages are drastically different.

Great post. I never understood why calculators even use a % for boil off. No matter how much water I have in my pot, I boil off 2 gallons per hour. Seems strange to have a percent when that will change with the amount of wort.


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[JoeSpartaNJ]

I brewed again today. I went back to my old burner and moved it back in the garage, used the same 15 gallon pot, and increased my calculated evaporation to 20%. I am happy to say that my final volume was a calculated 5.5 gallons and had about 1/2 gallon of hot break left in the pot.

Thanks everyone on the guidance.