Measuring boil off rate

[OmegaRed]

I have a 26 gallon kettle. Almost 20" opening.

That being said, I just hooked up natural gas to my BG14 burner, and trying to establish a good number for boil off rate. The first two brews on propane I got much more evaporation than I initially thought.

That being said, I put in 5 gallons and boiled for an hr. Got about 2.75 gallons of loss. I think it's crazy high. This was from heating until boiling, then I boiled for an hr.

Or should you heat with a lid on and then once it starts to boil take the lid off, essentially starting the timer or when you measure evaporation. Thanks

 

[HomeBrewMaster]

Thats a big kettle with a big opening the boil off you have doesn't seem to crazy to me. I have a 15 gal with a 18 inch opening and boil off 2 gal in an hour.

 

[sboyajian]

I always feel inadequate when it comes to boil-off rate .. My 10 gallon pot boils off about 3/4 of a gallon over an hour.

 

[d3track]

My 10g boils off almost 2g per hour, so I don't think it's too bonkers

 

[PrinceOfThePoint]

Whether or not it seems high, it's still correct data

It is possible that the boil off rate of water from real sweet wort, as opposed to pure water, could be slightly less due to slight boiling point elevation, but it's likely a negligible difference.

Your rate may be on the higher end of the spectrum but it sounds completely valid.

 

[OmegaRed]

Ok good to know. So when you guys measure boil off, you take your initial volume, and leave it uncovered while heating until boiling. Then once it reaches 212, start your hour timer?

I just wanted to make sure my evaluation method was similar.

 

[ScrewyBrewer]

I use a 15 gallon kettle that has a 15 inch diameter and my boil loss is 1.25 gallons per hour. I leave the lid off the entire time it's heating up and take a pre-boil volume reading right at the start of the boil. An hour later I take my post-boil volume reading to calculate the actual boil loss. Hope this helps.

 

[Hopper5000]

That's not too crazy. I usually get a boil-off of about 2.5gal in a 15gal pot doing a 5 gal batch. The more volume you have in there the less it will boil off. However, I would try to boil about 7.5 gal with your setup and see where it gets you. With that big of a pot just do 10gal batches!

 

[OmegaRed]

That's not too crazy. I usually get a boil-off of about 2.5gal in a 15gal pot doing a 5 gal batch. The more volume you have in there the less it will boil off. However, I would try to boil about 7.5 gal with your setup and see where it gets you. With that big of a pot just do 10gal batches!

I do BIAB 10 gallon batches, but just did 5 gallons for the boil off test.

Thanks for the help everyone, now for another test run and brew tonight.

 

[Hopper5000]

Gotcha . I think around a 20-30% boil-off rate is pretty standard.