High boiloff rate compensation

[panka16]

For my last batch, a rye pale ale, I lost over 4 gallons to boiloff. I am using an 80 quart aluminum kettle with a very wide opening (about 20''). I know this isn't ideal and is a huge part of the problem. I am planning a high gravity stout for this weekend, 2 gallons. To compensate for the ridiculous boiloff, I calculated I will need about 21 lbs of grain to hit an o.g. of 1.075. Does this sound feasible? I'm having a hard time wrapping my head around this.

Prost!

 

[EdWort]

Just add more water at the end of your boil to make up the difference.

 

[Changeduser123]

I am not sure why you would need to compensate your boil off rate by adding more grain .... Would you mind sharing your thoughts behind this ? Please detail your process and water volumes.

 

[EdWort]

I am not sure why you would need to compensate your boil off rate by adding more grain .... Would you mind sharing your thoughts behind this ? Please detail your process and water volumes.

Exactly. With the higher boil off, your gravity will be higher already, hence my recommendation to add water at the end of the boil to make up for excess evaporation. My Blingmann 20 gallon kettle does the same if I crank it to a roiling boil, so I will add at the end to hit my volume numbers and reduce the gravity.

 

[StMarcos]

Turn the power down.

 

[emetcalf]

For my last batch, a rye pale ale, I lost over 4 gallons to boiloff. I am using an 80 quart aluminum kettle with a very wide opening (about 20''). I know this isn't ideal and is a huge part of the problem. I am planning a high gravity stout for this weekend, 2 gallons. To compensate for the ridiculous boiloff, I calculated I will need about 21 lbs of grain to hit an o.g. of 1.075. Does this sound feasible? I'm having a hard time wrapping my head around this.

Prost!

21 lbs for 2 gallons is WAY too much. How did you get that number? Assuming you get 70% efficiency (shouldn't be hard since you will be able to use a TON of sparge water) you should only need around 6 lbs. Your boil off rate doesn't change how much grain you need to use, it changes how much water you should use.

 

[panka16]

Ahhhh...gotcha. I'm a bit of a noob to all grain, I must have gotten my wires crossed somewhere. Thanks for clearing it up. Here's my recipe, any suggestions? http://hopville.com/recipe/925814/wood-aged-beer-recipes/super-bowl-bourbon-stout

 

[emetcalf]

Wait, are you still going for 2 gallons or did you change it to 5? It's showing a batch size of 6.5 gallons.

 

[panka16]

Yep, I switched it to 6.5 gallons, brewed it on Saturday. Missed my O.G. by about .01, I'm chalking it up to not quite hitting my sparge temp. Also, I really toned down the heat for the first 30 minutes of the boil and realized I was going to have way too much at the end of 60 minutes, so I ended up doing a 90 minute boil with it wide open for the last half hour. Nailed it right on 6.5 gallons. SO, it tuns out my ridiculous boiloff rate was due mainly to too much heat. Another batch, another lesson or three learned! I'm pretty psyched to try this one. I will post tasting notes on hopville. Thanks for the help.