Boil-off rate???

[Allekornbrauer]

Hello how would one go about testing there boil-off rate??

 

[Pkrd]

Fill your kettle to your expected pre boil volume, boil for an hour, measure the change in volume. Thats gonna be close to your gal/hr boil off rate (it will be a little different to wort).

 

[Silver_Is_Money]

Fill your kettle to your expected pre boil volume, boil for an hour, measure the change in volume. Thats gonna be close to your gal/hr boil off rate (it will be a little different to wort).

Cooling will shrink it another 3.5% to perhaps 4%. So be sure to measure cooled post-boil volume vs. cooled pre-boil volume. My wort boil off rate is consistently about 1.12 gallons per hour (4.24 Liters per hour).

 

[RM-MN]

Make a batch of beer. Measure how much wort you have before you start the boil. Measure how much is left after the boil. The difference is the boil off. Doing it with wort you end up with good data and beer. Doing it with just water, you end up with good data and hot water. What will you do with a bunch of hot water?

 

[Dgallo]

Cooling will shrink it another 3.5% to perhaps 4%. So be sure to measure cooled post-boil volume vs. cooled pre-boil volume. My wort boil off rate is consistently about 1.12 gallons per hour (4.24 Liters per hour).

*edit* I stand corrected

 

[Big Monk]

Ideally you want the measurement for your boiloff to be a percentage not gallons or liters. That being said, if you’re only brewing one batch size for all your beers then certainly knowing the boil off in a volume measure would be beneficial.

You want to know the value in l/hr or gal/hr.

This won’t change due to batch size. Percentage based boil-off is extremely flawed for anything except tracking.

For instance, if I use the same kettle for all batches, and my known boil off for a 60 minute boil is 4 liters, then for a preboil volume of 28 liters that’s 14% boil off. Now if my preboil is 20 liters, that’s 20% boil off. That don’t jive.

Percentage based boil off is an inferior metric for determine evaporation volume, which for a constant kettle size but variable volumes is the same value.

 

[Dgallo]

You want to know the value in l/hr or gal/hr.

This won’t change due to batch size. Percentage based boil-off is extremely flawed for anything except tracking.

For instance, if I use the same kettle for all batches, and my known boil off for a 60 minute boil is 4 liters, then for a preboil volume of 28 liters that’s 14% boil off. Now if my preboil is 20 liters, that’s 20% boil off. That don’t jive.

Percentage based boil off is an inferior metric for determine evaporation volume, which for a constant kettle size but variable volumes is the same value.

I’m mistaken then

 

[Big Monk]

I’m mistaken then

I look at it this way: The amount of evaporative loss as a percentage is still a very useful tracking metric.

Let's say that I am very conscious about the intensity of the boil as it relates to thermal stress on the wort. I boil of 2 l/hr on a 22 l pre-boil volume. On a 60 minute boil, that's 9% boil-off.

Now let's that I need a batch with a larger volume, say 36 l Pre-Boil. That's 5% boil-off. Knowing that metric can add value for me in the sense that I may not get the desired results from a lower %. Maybe I use that value to increase the power input from my heat source to boil more intensely.

Knowing it for that reason is valuable as opposed to basing your evap loss (in l or gal) on it.