Question on boiling volumes

So I'm about to brew the saison recipe from the may-June 2012 edition of byo magazine and was curious if it is possible to boil 6.75 gallons of wort in a 7.5 gal bk? I just finished building my all grain setup with a 7.5 gal bk, 45,000 btu burner and 10 gal mlt (using the mlt build in the diy section here on HBT.) If it is gonna be close, are there any tricks to prevent a boilover?

 

Yes. Boil at 101C.

 

I wasn't asking if the burner was capable of boiling 6.5 gal. I was asking if it was a guaranteed boilover or not?

 

I understand what you were asking, but you didn't understand my reply. Boil overs occur when you are boiling too far beyond the boiling point of 100C. Do you use a thermometer in your BK? If not, please do and hold it at a steady 101C. The boil shouldn't create a huge bubbling cauldron of wort. A boil at 101C appears very gentle to the eye, almost like it isn't boiling at all, but it is because science says so.

You are certainly cutting it close, but you should be fine as long as you don't blast it with too many BTUs initially. Start on a lower heat setting and gradually bump it up until you reach 101C.

 

I'm always boiling 12.5 gal in 13.2gal kegel, i have to be very careful at the beginning of the boil and when adding 60 min hops but after that is no problem so I guess u should be fine

 

O.K. I understand now. Thought you were just being a smart a$$. As this is my first time boiling with this setup I will be sure to watch the temps. Thanks alot

 

That is the key. Be very careful in the beginning. In other words, if you can maintain a boil at 101C using 50% of your system's BTUs, you definitely should not start at 100% until it boils because you will probably boil over which can happen in less than 5 seconds.

You should also use a sharpie to mark the position on your gas valve where a temp of 101C can be maintained.

 

You're welcome and I'm often a smart a$$ in a playful way, but this is not one of those times. Good luck with the brew.

 

My bk only comes close to boiling over when the hot break happens and that's usually as I get to about 200, which is under boiling temp so the temp being too high doesn't come into play there. Keep a spray bottle full of water with you while you boil... Helps me keep it down if the boil starts climbing up too high.

 

Get a spray bottle, put super cold water in the bottle, if you see the wort about to boilover, spray the wort for acouple of seconds...
or fermcap....
igotsand

 

It is possible to boil over a 7 gallon wort in a 10.5 gallon BK. I came very close my first time. I used way too many BTUs initially and realized that 45,000 BTUs are complete overkill for a gentle boil.

 

The cold spray bottle method apparently works. I've never tried it because reducing your level of BTUs when you see the wort start to rise quickly can prevent a boil over just as quickly as you can reduce your BTUs.