I have been getting very high evaporation rates so I did a little experiment the other day. I put 7 gallons of water in my pot and cranked up the heat. It took a little while to get that much water from approx. 70 degF to boiling, probably 45 minutes. After it began boiling I let it go at full heat as if I were brewing for 15 minutes then measured my volume. Based on that volume reduction in 15 minutes my evaporation rate was 28% per hour, VERY HIGH, right? I continued to let it boil for another 15 minutes, measured, then another 15 minutes, measured and finally for another 15 minutes and measured. The evaporation rates for the last 3, 15 minute intervals was on average 15% per hour. This tells me that I am loosing liquid during the 45 minutes it takes to get to full boil. That all being said, is it ok to leave the lid on the brew pot until it comes to boil and then remove for the boil time. I know you are supposed to boil with lid off but I have never read anything about covering until you get to the boil. Thanks.