We are getting ready to brew the Ace of Spades extract. We just got a new Mega pot 10 gal kettle and would like to do a full boil. What should our pre-boil volume be? Is there a rule of thumb amount, or is it always dependent on what your brewing?
My 10gal pot usually boils off about 1 - 1.5 depending on how fast it boils. I shoot for 5.5 or 6 in the fermenter. So I boil 6.5 to 7. If your boiling 7 gal in a 10 gal pot you have to stay on top of it. If you are using a kit you may want to shoot for exactly 5 gal in the fermenter since I think that is how the recipe was designed. If it were me I’d boil 6 gallons for a 5 gal extract kit or an all grain kit for that matter.
Lots of variables to determine boil-off but the biggest is kettle geometry and how hard you boil. If you don’t mind wasting a little propane, fill your kettle up with water to around the 7 gallon mark and boil it for an hour. This will give you an idea of the boil-off your system. This is very important when moving to all-grain so you know how much water to mash/sparge to end up with your desired pre-boil amount.
Also don’t forget that if you are using extract to account for the volume of the extract when you are figuring your pre-boil volume. 6 lbs of LME is roughly 1/2 gallon. So if you boil-off 1 gallon per hour and want a final volume of 5 gallons and your kit includes 6 lbs of LME, you would only need 5.5 gallons of water before you add the extract to get 6 gallons total. I didn’t think to account for that in my first few kits and ended up slightly low on OG because I ended up with more wort than target volume. :oops:
I screwed up on my first extract full boil and forgot to account for the volume of extract and almost had a boil-over. I had to boil an extra 45 minutes to get the volume down.
I always start out with 5.75 gallons of water and then add extract. I always seem to come very close to 5 gallons after the boil. I shoot to come out just a bit shy of the full 5 gallons so that I can accurately add the exact amount to hit 5 gallons in the fermenter.
You’ll need to determine you boil off rate, as mentioned by others, but you’ll also need to enter your recipe into a beer recipe calculator and determine your hop additions to match the IBU’s at a lower volume boil.
You might boil off 1 gallon per hour, so start with 6 gallons for a 5 gallon batch.
Your hop additions might change based on the amount you start boiling with.
Try checking the all grain recipe for that beer (if there is one).
If you want to keep it fun, don’t worry about the hops, or the boil off and just boil with 5 gallons, cool and fill back to 5 gallons. Record your boil off while you’re at it.
Thanks to everyone for the advice. It is all duly noted and will come in handy.