Boil volume

[YukonLT]

Hey guys, last weekend I did my first brew day. I did a 5 gallon batch from a brewers best kit that was an IPA. Everything went well, but I think I boiled off more than a gallon in my 6 gallon boil. It looks like I have about 4.5 sitting in my carboy. It was an hour long boil. I have read that you can lose between 1-1.5 gallons per hour, so I guess I was on the high end a bit, though I did spill a little bit in the transfer to the fermenter. I'm getting ready to do the Pliny clone this weekend, and want to make sure I get the volume correct. It's got a 90 minute boil, so should I start with 6.5 gallons to be safe, or go to 7 even? What factors effect evaporation the most? Thanks in advance guys, I appreciate any responses.

 

[duboman]

Are you boiling inside or outside? Ambient temperature, humidity, wind, geometry of the kettle, etc will all effect boil off rates. Also, once the boil begins you can drop the heat to maintain a nice rolling boil, the wort does not need to be jumping out of the pot

I lose a full 2 gallons in a 90 minute boil outside set up. You would be best to put a pre-measured volume of water in a pot and boil it for 90 minutes, measure what's left and you'll know your boil off rate.

 

[brent77]

You can always top off with bottled water to bring it back up to the 5/5.5 gallons etc.

 

[fuzzy2133]

...You would be best to put a pre-measured volume of water in a pot and boil it for 90 minutes, measure what's left and you'll know your boil off rate.

^^^ This; it sounds like the OP is doing full volume boils.

You can always top off with bottled water to bring it back up to the 5/5.5 gallons etc.

Topping off is fine if the kit was designed for partial boil (hop utilization and extract addition times). Adding water possibly could dilute the taste and mouth feel with a full volume boil.

 

[LovesIPA]

There are too many impossible to measure factors that contribute to boil-off rate. The only way to find out is to follow the above advice and see how your equipment performs. With my setup, I lose about 1.8 gallons per hour. It seems to be on the high side but others report even higher rates.

 

[YukonLT]

Yeah I'm doing full boils. Thanks for the tips guys, that's what I was thinking as well. I don't know how much research I will do though with this kettle because I plan to go to all grain very soon, and will be going to another set up.

 

[BryceL]

Based on your last brew it sounds like you boiled off 1.5 gal/hr. If your doing a 90 minute boil on your next one, I would plan for 1.5g x 1.5hr = 2.25 gallons.