Calculating boil off rate

[Gonefishing]

Amazon should be delivering a 10k watt SCR controller to me on Monday. I plan to use it to control the 5500 watt element in my BK. I have never used this BK before (in truth, it isn't put together yet) so I don't know the boil-off rate. My question is, can I determine that using straight water? If I only boil a known quantity for an hour one time and determine how much I boiled off would I have a good handle on the rate, or will I need to do a "practice boil" a few times to know that?

 

[triethylborane]

Yes, you can estimate using water, which will give you a rate that will work just fine for your brewing. Repeat a few times if you are really anal.


Ambient conditions (altitude/humidity/pressure), kettle dimensions, heat source power output will all change it boil off rate, but this is home brewing not NPN transistor doping.

 

[Gonefishing]

Thanks for your reply, triethylborane.
There's little danger of my being called anal because I'm normally the most disorganized person around. I'm just hoping that most of the time I could hit my planned numbers and have the ability to repeat a brew if all goes well. So, maybe I'll boil water a couple of times before I decide what the rate is but I'm not planning to do it so many times that I could create a spreadsheet or anything, I just need a number to put into the recipe planner.

 

[Sailingeric]

I think it comes down to doing a few batches to see what you average out. My cheap 7.5 gallon pot would do about an gallon an hour but my 15 gallon SS pot is closer to two gallons an hour so for my preboil volume at 7 gallons and it comes out dang close to 5 gallons into my bucket every time.