How much does boil kettle size matter? (small batch in a keggle)

[MMBB]

It has been three years since I have done an extract batch of beer and I am going to help a friend brew for his second time tomorrow. My question is if a keggle, or a smaller 10gal kettle, would be appropriate for boiling the wort. Would there be too much evaporation with either of these during the boil? IIRC the kit doesn't give instructions for a full volume boil but only for adding water after the boil.

 

[mjdonnelly68]

Until you test out the specific kettle, you won't really know the boil off rate.

I've found that a good assumption rate is 1 gallon per hour at a rolling boil.