What's an accurate evaporation rate for the hour long boil?

[Tankard]

I'm tweaking the Beersmith settings and the default evaporation rate is 11%. So I would collect 7 gallons of wort and boil down to 5.5 gallons in an hour. That sounds a bit high. Has anyone ever calculated this based on a turkey fryer setup? I have a 30 qt aluminum pot.

Or, what do you have your Beersmith evaporation rate set at? How close is it, typically?

 

[r2eng]

11% is my evap rate on our gas stove in the kitchen.

I took my straight-sided 7 gal kettle and added 3 gals of water, boiled for an hour and measured. Boil off is based upon temp and surface area exposed to the air.

Use this experiment to calculate for beersmith.

Eric

 

[Yooper]

I boil off about 6% in an hour in my turkey fryer pot and stove top set up. It really depends on how high your burner is going, and how dry it is in your climate.

 

[Chad]

Mine runs about 9% per hour. Whether I'm using a Bayou Classic SQ14 with 10psi regulator under a keggle or my crappy electric stove under a 32qt pot, it stays pretty consistent.

Chad

 

[makapol]

did everyone measure the evaporation at flame out (burner out) or after cooling to room temp, pitch temp?

 

[AnOldUR]

. . . . what do you have your Beersmith evaporation rate set at? How close is it, typically?

For my Bayou Classic SQ14 and an 11 gallon aluminum pot I have BS set at 15% for a 5+ gallon batch with .4 gallons lost to trub. When I do a 3+ gallon batch with the same equipment I use 18% evaporation rate and .3 lost to trub.

Mine runs about 9% per hour. Whether I'm using a Bayou Classic SQ14 with 10psi regulator under a keggle or my crappy electric stove under a 32qt pot, it stays pretty consistent.

Damn! I must be using too strong a boil

 

[stevecaaster]

For my Bayou Classic SQ14 and an 11 gallon aluminum pot I have BS set at 15% for a 5+ gallon batch

Damn! I must be using too strong a boil

I have the same problem going, I was losing like 19 percent per hour, but that sq14 can get mighty hot, and I always put it on FULL BLAST when i use it, which is a mistake...

from now on I am going to go FULL BLAST until i get a boil, then back off A LOT till just enough flame to keep the boil...

 

[jds]

I boil off about a gallon per hour (in Denver) from my keggle with a gently rolling boil. It doesn't seem to matter how much wort I have in the keg, so I have to fiddle the numbers to get accurate evaporation rates. That works out to be about 14% for 7 gallons of initial volume.

 

[Bobby_M]

Percent doesn't work for me. Boiloff is usually a fixed amount no matter how much liquid is in the same kettle. I lose about 1.5 gallons in 70 minutes in my keggle regardless if I start with 13 or 8 gallons.

 

[Tankard]

I tested my evaporation rate today. I lost a little more than a gallon during the hour long boil (About 1.2 gallons). Do I just divide 1.2 gallons by the amount I started with (7 gallons). That's about 17.1 percent. Does that sound normal?

 

[CHansen6]

I too have always found the boil off in percentages rather odd at times. In the same pot a gallon of water will boil off just as fast if there are 5 gallons in it or 10 gallons. I've down sized a few recipes from 10 or 20 gallons to 5 gallons, and the collection values and the volumes came out odd a few times. I think it depends much more on equipment.

There might have been some sort of boil off perfect storm on my last brew. I lost close to 2 gallons in a little over an hour of boiling. There was a slow cooling process, so I would imagine I lost more than usual to evaporation. I found out after I was boiling that my roommates lent away the large plastic tub we have that I usually cool the pot in. Trying to cool a 30qt pot in the sink did not go well or fast. I had to top it back off, but it seemed to come out just fine, well despite it blowing the top off the fermenter.

 

[skinfiddler]

For three brews, (for whatever reason) my boil-off has been 7% short from Beersmith numbers. Next time I plan to increase their numbers by that much in the pre-boil volume.

 

[TexLaw]

I tested my evaporation rate today. I lost a little more than a gallon during the hour long boil (About 1.2 gallons). Do I just divide 1.2 gallons by the amount I started with (7 gallons). That's about 17.1 percent. Does that sound normal?

From my experience, you are better off fixed volume per unit time, rather than a percentage. It sounds like you boil about 1.2 gallons/hr.


TL

 

[jay075j]

I've always just calculated mine at 1 gal per hour. It always seems to work out better by using a fixed volume rather than a percentage. IMHO of course.

 

[nathan]

I have a decent idea where mine should be as the boil goes, up until I stick the immersion chiller in it. So I take note with 15 min left and if I need to, I crank up the flame, but I prefer a gentle "simmer" for my boils instead, as the wort darkens less. I'd rather end up a tad under volume and add boiled water I've got stored to get to volume, then aerate and pitch.

 

[blacklab]

From my experience, you are better off fixed volume per unit time, rather than a percentage. It sounds like you boil about 1.2 gallons/hr.


TL

Exactly. The boiloff rate is related to the surface area of wort exposed to the environment, and the temp of the boil. A % implies that this will vary with volume, which it can't. Regardless of your volume, your boil off will remain constant in the vessel you are using, if you boil at a consistent temperature. My system is 7 gallons to 5.5 gallons @ ~212 every time.

 

[EdWort]

The Blichmann Boilermaker 20 gallon kettle will boil off 2 gallons in 90 minutes. I'm attributing that to the larger diameter of the kettle compared to a keggle.

 

[blacklab]

The Blichmann Boilermaker 20 gallon kettle will boil off 2 gallons in 90 minutes. I'm attributing that to the larger diameter of the kettle compared to a keggle.

showoff!

 

[WBC]

I don't think ED has a Blichmann and he is just pushing your button but .....
Did you buy one ED?

 

[chillHayze]

I figure 3 gallons for boil-off, chill loss (contraction), and trub losses, so I usually boil 8-8.5 gallons (I am picky about not getting the break protiens in the fermentor). It is not really relative to initial boil volume as others have said. Pretty much flat rate for a normal batch.

No doubt there is a point where the curve swings rapidly, just not in the area us HBers are working.

 

[neldred]

Is trub loss generally the same regardless of 1, 2.5, or 5 gallon batches? Will trub amount effect ABV or Gravity, since its actually a solid (or are you precalculating in beersmith to compensate for trub)? Thanks...just getting back into brewing after taking a year break.

 

[RedHouse]

I boil off almost 2 gallons in an hour. I figure on almost 8 gallons into kettle, 6 after the boil, 5.5 into fermenter, and 5 into bottling bucket.

 

[cswank]

I have an automatic brewery that I've been using for 7 batches now. It is all enclosed in a attempt to retain heat during the mash, and to not get my basement all steamy when I brew (all electric). I have a duct fan that vents out the window. This time I started with 6.5 gallons before the boil, and after 60 minutes I was shocked to find I had lost 3 gallons! My OG was 1.080 and I didn't have a yeast starter ready. I have a bad feeling about this batch.

The difference between this batch and the previous 6 is that I took the lid off of the boiler for the entire boil. Before I would leave it on, but off to the side a bit so about ~30% of the boiler was uncovered. I don't know if the vent fan increases the evaporation rate when I have no cover on the boiler but I'm going back to covering it to avoid disasters such as this (I presume it will be a disaster, but I'll have to wait until I drink it to make sure).

Moral of the story: If you have an enclosed brewery contraption with a duct fan attached, don't boil without a lid

Maybe I'll try again without the lid, but not boil so vigorously and leave the duct fan off.

 

[tesilential]

Why don't you add water to your fermenter to dilute closer to your intended OG?

 

[cswank]

Good god, why didn't I think of that? Thanks!

 

[05willys]

Good god, why didn't I think of that? Thanks!

You should leave the lid off to allow dms to evap, but get a less powerfull fan. Imho.

 

[TrogdorTheBrewinator]

I have a 15 gallon stainless and my loss is a bit over 2 gal per hour.

 

[FredTheNuke]

I have an automatic brewery that I've been using for 7 batches now. It is all enclosed in a attempt to retain heat during the mash, and to not get my basement all steamy when I brew (all electric). I have a duct fan that vents out the window. This time I started with 6.5 gallons before the boil, and after 60 minutes I was shocked to find I had lost 3 gallons! My OG was 1.080 and I didn't have a yeast starter ready. I have a bad feeling about this batch.

The difference between this batch and the previous 6 is that I took the lid off of the boiler for the entire boil. Before I would leave it on, but off to the side a bit so about ~30% of the boiler was uncovered. I don't know if the vent fan increases the evaporation rate when I have no cover on the boiler but I'm going back to covering it to avoid disasters such as this (I presume it will be a disaster, but I'll have to wait until I drink it to make sure).

Moral of the story: If you have an enclosed brewery contraption with a duct fan attached, don't boil without a lid

Maybe I'll try again without the lid, but not boil so vigorously and leave the duct fan off.

Don't forget that completely covering it traps the Dimethyl Sulfide instead of letting it boil out of the wort...

 

[bobbrews]

It's different for everyone and depends on many factors, including kettle diameter, boil strength, altitude, etc.

I lose 0.80 gallons per hour under a vigorous boil. For my partial mash process, I only lose about 0.20 gal to trub. So that makes things easy calculations wise

 

[frailn]

I was losing 0.9 gallon/hour in my 7 gallon aluminum turkey fryer. When I switched to a 15 gallon SS kettle, I started losing 1.75 gallon/hr. It just depends on your equipment.

I did a test run with plain water to measure my boil off. Then, I check it every time I brew to dial into an average.