The boil off rate is one of my bigger variables these days. I missed my mark by about a quart on the last few batches. This equates to about 4 gravity points. The beer is fine but I am stickler for hitting the OG target. I adjust the burner to acheive a vigorous rolling boil but visually the appearance doesn’t change that much when you get to a certain point. Typically I boil off about 1.3 gal per hour. Right now I am thinking that when the boil looks about right, turn the gas pressure up.
Anyone have any recommended procedures ?