2.5 gallon boil off rate

[msujay]

I'm planning a 2.5 gallon small AG batch today and wanted to get some input on boil off rates. Assuming I boil off 1 gallon per hour for a 5 gallon batch, using a standard turkey fryer setup, what should I assume for a 2.5 gallon batch boil off using the same equipment?

 

[Yooper]

The same. It's not really a % that boils off, it has more to do with the size of the kettle. So, for a 10 gallon batch in the same pot, you'd get about the same boil off as a 3 gallon batch, or a 5 gallon batch.

So, if you boil off 1 gallon an hour in a 5 gallon batch, in the same pot you should boil off about 1 gallon an hour.

 

[joety]

Agreed, don't know where you live but my boil off rate is wayyyy different in the winter than the summer as well. Summer is about 1 gallon/hour, winter is 1.5 or more.

 

[peterdulay]

Oh man. I brewed a 6 gal batch last night. ( i always do a little more for these types of instances) I used a new 10 gallon kettle for the first time. This one is stainless and my normal one is a 10 gallon aluminum. I lost 2.6 gallons during my boil. So frustrating because my o-gravity was off by 12 pts too. I took it before I added a gallon of water back in to make up the volume. Could this volume problem be a winter thing? Could boil off effect my gravity this much too?

BTW here was my bill:

15lbs 2-row pale
1 lb. Canadian Wheat Malt
1 lb. Munich Malt
2 oz. Cara-munich
1.5 lbs Cane Sugar

I always increase my base malt by 3lbs more than what most recipes call for because my BH efficiency has been so low in the past.

 

[pinback]

Why not keep on sparging until you hit the gravity you are looking for. Then considering your boil off rate, you can sort of get it close in terms of volume, although you may have to boil longer.

 

[peterdulay]

yeah boil was already 90 minutes. I'm not so sure I wanna heat up water again. I'd rather just go back to mu equip. I looked up various reasons for excessive boil off in here in HBT. It seems its (boiling down to )
1) thickness of kettle and,
2) BTUs used with
3) a marginal effect from humidity level changes.

going to invest in stainless kegs.