Boil off rate is HIGHLY variable! :ugh:

[Jayhem]

Normally I have a pretty good idea of what my starting volumes need to be pre-boil in order to end at the right volume of wort at flame out.

Well, lets throw in the variables of humidity, outside temp and wind speed into the mix....

Last night I brewed a Kolsch and should have boiled off about 1.5 gal/hour under normal conditions but we had low humidity and high winds (I boil outside). I lost 1.5 gallons in the first 35 minutes! Ended up having to add over 3 quarts of water before flame out to get close to the right volume and still ended up 2 quarts shy with a higher than desired OG. that means I was boiling off more than 2 gallons/hour :smack:

I guess figuring out your equipment profile needs to be adjusted to account for current weather conditions.

 

[Yooper]

Yes, that does happen.

I brew indoors, but I have a different boil off in the winter when it's much drier than in the summer when it's more humid, even inside at roughly the same temperature and same power setting.

Adding water after the boil to lower the OG and bring up the volume is fine, though. It's much better than having way too much wort at the end and having a too-low OG so it's not too bad to aim low and top up.

 

[Jayhem]

Yes, that does happen.

I brew indoors, but I have a different boil off in the winter when it's much drier than in the summer when it's more humid, even inside at roughly the same temperature and same power setting.

Adding water after the boil to lower the OG and bring up the volume is fine, though. It's much better than having way too much wort at the end and having a too-low OG so it's not too bad to aim low and top up.

Thanks for the comment.

Yea I'd rather undershoot and top up. I had to do a good 90 min boil on this one because it's a Kolsch using Pilsner malt and I want to be rid of DMS. I always do 90 min boils though and usually only lose 2 gallons in that time.

 

[dtwhite]

For me it's mostly the wind's fault. Windy days mean I lose WAY more water.

 

[Spartan1979]

I had the opposite problem last weekend. I brewed a Maibock and after the boil I was only at 1.050 with too much volume. I had to boil for another half an hour to get to 1.067. I was only a quart short on my volume. My 60 minute hop addition boiled for 90 minutes and my 30 for 60 minutes.

 

[jCOSbrew]

Consider using a "calibrated" spoon for the BK with volume marks. Check the volume after about 30 minutes and add or remove heat for the remainder of the boil to adjust the boil off rate.

 

[Jayhem]

Consider using a "calibrated" spoon for the BK with volume marks. Check the volume after about 30 minutes and add or remove heat for the remainder of the boil to adjust the boil off rate.

I do use a brew paddle with marks at each gallon mark in my specific kettle. I track the loss of wort to boil off ever 10 minutes and it was simply going MUCH faster in windy, dry conditions than usual. I like that idea though. at the half way mark through my boil time I should have lost exactly 50% of the wort I need to lose in order to hit flame out volume target. It's best to boil off too fast and top off at the 30 min mark so I hit my target!