boiloff rates

[Arkador]

I am gearing up to do my first outdoor boil, and am trying to get an idea of boiloff rates to avoid using topoff water.

1: Sanke Keggel
2: Banjo 55000BTU turky fryer
3: 85-95degree Tesas day

I am hoping someone will have an idea of how much volume i should try to do
a: 10gal final volume
b: 5gal final volume
with a 1hour boil.

My other option is to throw in a measured amount of water, and measure what comes out after a 1hour test boil.

 

[feedbag]

According to BrewSmith, assuming an average standard boil off rate of 9%, you would need 11.45 gallons for 10 final gallons, and 5.72 for 5 final gallons. That is assuming a 60 minute boil. I think most people round up a bit to count for trub and hop waste though.

 

[Vic_Sinclair]

Don't forget to figure in your extract into your initial volume figure. The first time I did a full boil, I ended up with 5 1/2 gallons because I failed to account for the cans of extract.

 

[The Pol]

Holey Moley...

#1. You cannot use a % as a boil off rate, unless you are comfortable assuming that you will boil off 2x as much on a 10 gallon brew as you do on a 5 gallon brew.... it simply doesnt compute. Doesnt make sense does it?

#2. Boil off is a constant

#3. In a Sankey, you can expect about 1.3gal/hr boil off

#4. With 13,140 BTUs going into my BK, I get 1.35gal/hr boil off

#5. With propane, your boil off will vary as it is unlikely that you will set the burner the same each time

#6. The best way to compute this, is to get about 7 gallons in your kettle and boil it for an hour, then meausure what is left.

DO NOT use % for boil off, and do not assume 9%, boil off rates are generally about 15-20%. Why some brew software uses a % is beyond me, but you cannot represent boil off rates, which are constant, as a %. If you boil off 1.3 gallons with a 5 gallon brew, you will boil off the same with a 10 gallon brew, all things considered equal.

 

[feedbag]

Holey Moley...

#1. You cannot use a % as a boil off rate, unless you are comfortable assuming that you will boil off 2x as much on a 10 gallon brew as you do on a 5 gallon brew.... it simply doesnt compute. Doesnt make sense does it?

#2. Boil off is a constant

#3. In a Sankey, you can expect about 1.3gal/hr boil off

#4. With 13,140 BTUs going into my BK, I get 1.35gal/hr boil off

#5. With propane, your boil off will vary as it is unlikely that you will set the burner the same each time

#6. The best way to compute this, is to get about 7 gallons in your kettle and boil it for an hour, then meausure what is left.

DO NOT use % for boil off, and do not assume 9%, boil off rates are generally about 15-20%. Why some brew software uses a % is beyond me, but you cannot represent boil off rates, which are constant, as a %. If you boil off 1.3 gallons with a 5 gallon brew, you will boil off the same with a 10 gallon brew, all things considered equal.

Thanks for that info, I didn't realize boil off rates could be that high.