[Hdguy]

I am planning to do my first all grain recipe. I have an 8 gallon kettle for brewing. According to my calculations I will need to start with 7.5 gallons of run off for a 90 minute boil. I am concerned with boil over at the beginning of the boil. Can I fill the kettle with 6 gallons of run off and start the boil and add the rest of the run off as it boils down? Should I just fill up the kettle and try to keep a gentle boil at the start and increase the boil as the level drops?

[RPIScotty]

What is your boil off rate in gal/hr? What is your batch size? Why do you need to boil for 90 minutes?

There are many variables here: process, equipment specific losses, etc. if you could provide some more details you will most certainly get some good responses here.

[denny]

I am planning to do my first all grain recipe. I have an 8 gallon kettle for brewing. According to my calculations I will need to start with 7.5 gallons of run off for a 90 minute boil. I am concerned with boil over at the beginning of the boil. Can I fill the kettle with 6 gallons of run off and start the boil and add the rest of the run off as it boils down? Should I just fill up the kettle and try to keep a gentle boil at the start and increase the boil as the level drops?

Yeah, that's one solution.  When I was in that situation, I decreased the efficiency I used for recipes calculations so I made a smaller volume of stronger wort, then topped up after the boil.

[Stevie]

I've done the top-up method as well. One benefit is quick cooling if the top-up water is cold and sanitization enough to add straight to the kettle.

[Hdguy]

The recipe I have calls for a 90 minute boil to end up with 6.0 gallons. I don't know my specific boil off rate. I guessed at 1.5 gallons per hour. It may be more or less than that but I had to start somewhere. My elevation here in Washington is 200 feet so that may affect the boil off rate from what I was used to when I lived in Nebraska at about 3000 feet.

I don't know a lot about figuring efficiency etc. The recipe I have says efficiency is 75%.

My main concern is will it drastically affect the final product if I top off during the boil or add water to the primary fermenter to achieve the 6 gallons of beer.

I've always done extract brewing so I just added water to the primary fermenter to achieve the desired volume.

[Stevie]

Will topping-up have an effect? Sure. Will it be significant at the volume you are adding? Doubt it.

I would play it safe for the first batch and plan on topping up with a gallon. From there you can better understand your kettle and adjust from there.

[Hdguy]

Will topping-up have an effect? Sure. Will it be significant at the volume you are adding? Doubt it.

I would play it safe for the first batch and plan on topping up with a gallon. From there you can better understand your kettle and adjust from there.

Thanks. I was planning on keeping the extra runoff from the tun separate and adding it to the kettle as it boils down. It would amount to about a gallon. I know how messy boil overs can be so I wanted to keep the volume in the brew kettle low enough to prevent it. The other option I considered was adding it to the fermenter after cooling the wort.

[Stevie]

I've added additional runnings in the past and felt it was too much of a PIA. Keeping an eye on the evaporation and adding the additional runnings bit by bit is just too hands on for me. Adding cold sanitary water is my preference.

[denny]

I've added additional runnings in the past and felt it was too much of a PIA. Keeping an eye on the evaporation and adding the additional runnings bit by bit is just too hands on for me. Adding cold sanitary water is my preference.

Same here.  And the ribbons on my attest that it doesn't negatively affect beer quality.