Brew Boss / Boil rate question

[brewswithshoes]

Looking for any help from other Brew Boss owners or those familiar with boil off rate calculations.

I did a wet run on a new BB 15G system, but only did 30 minute boil thinking i could get the hourly boil rate by just doubling.

However, i noticed on trying to get more calculations, the water cooled & shrank so in trying to get my cooling rate/percentage i'm thinking i maybe should have boiled the whole hour so i would have known the actual ending volume.

Here is what i got on the wet run:

Starting Volume: 8G
Starting temp:72 degress
Time to boil temp (211 degrees for me): 34 mins
30 minute boil volume: 7.35G (.65G)
Cooled back to ambient volume: 6.7G

Do I have to start over and do a full hour boil, to get the true cooling percentage? or can i still figure that out from this??

 

[Nmnbrewer]

Cooling should be 4% or .294 gal. So boiloff is around .35 gal per 1/2 hr or .7 gal per hr. What % do you have your pwb set at? Thats low compared to mine set at 70% pwb. I get about 1.25 gal per hr boiloff at 70% pwb.

 

[Nmnbrewer]

If my calculations are incorrect please correct them anybody.

 

[Nmnbrewer]

Btw. I do use the BB controller but have a spike kettle 20 gal. Same element as on on the BB systems as well.

 

[brewswithshoes]

i think my hourly boil off rate is 1.3G/hr since i lost .65 in the 30 minute boil. I was just surprised that the volume drop so low when cooling. granted, i just let it sit uncovered and settle back to ambient over several hours, but that it went from 7.35G from when i stopped the boil, to the 6.7G after it was cooled back to ambient. i seem to have lost more in cooling from a percentage view than i did with the boil. that is what is messing me up when trying to do any calculations as that cooling rate doesn't seem right.

Did i maybe lose an unusually high amount to evaporation during cooling since i just let it sit for several hours to go back to ambient??

 

[brewswithshoes]

i've left my pwb at 63% as that seemed to be a decent/slightly low rolling boil for me