What is your Boil Off?

[Hamaki]

I also have a problem with the 15% thing. Is this 15% of pre or post boil volume? For 5.5 gal at the end of the boil you're looking at a little under a gallon boil off either way. Also, if I boil off 15% per hour I can never boil the pot dry, can I? I haven't measured but I suspect that for a given kettle and a given heat input under the same environmental conditions I'd boil off a little more per hour doing a 5.5 gal batch vs 11 gallons.

 

[TheZymurgist]

I've had almost 25% boil off (1.5 gallons/hour with a 6.5 original boil volume) and have never had any issues with attenuation or caramelization or "bready" characteristics, and can't tell the difference between my beers and beers brewed on other systems with lower rates of boil off, so I call BS. Not saying it's not possible to negatively affect your beer with too rigorous a boil, but to make a rule based on boil off percentage is complete crap.

 

[acidrain]

The pod cast that the article was written from is here: http://s125483039.onlinehome.us/archive/bs_melanoidin_7-19-08.mp3
If you want to get to the good parts:
12:15 to 28:40 they talk about flavors.
32: to 46:10 they talk about decoction vs. extended boil vs. ingredients.
48:00 + Boil off rates and at over 15% per hour, will everything taste like a boch? The answer is all equipment is different, but generally speaking, a vigorous boil caused by excessive thermal loading will create undesirable melanoidins.
25% is definitely too much.
20% with undesirable maltiness would indicate too vigorous of a boil.
By controlling the heat, you should be able to control the boil off.
Those guys shoot for no more than 15% per hour.

I use a turkey fryer burner that is not very adjustable.
I have noticed caramelization on the bottom of by BK in the shape of the flame.
Having had problems with what I will call a sickening sweet flavor, I can certainly see how those flavors could have been caused by melanoidins created by excessive thermal loading of the BK.

Listen to the pod cast and decide for yourselves.
I think cjgenever has brought up valid and important info. Thanks!

 

[max384]

I also have a problem with the 15% thing. Is this 15% of pre or post boil volume? For 5.5 gal at the end of the boil you're looking at a little under a gallon boil off either way. Also, if I boil off 15% per hour I can never boil the pot dry, can I? I haven't measured but I suspect that for a given kettle and a given heat input under the same environmental conditions I'd boil off a little more per hour doing a 5.5 gal batch vs 11 gallons.

It is 15% of preboil. When figuring boil off rate, you always do it as a percent of starting volume. Using a percent per hour figure, you technically can't boil the kettle dry... However, as a brewer, we're only concerned with the boil off rate for one hour, or maybe 90 minutes with some brews, so that little technicality is a non-issue. It does, however, make more sense to measure boil off rates in volume/unit of time (ie. quarts per hour) than a percentage IMO.

And in actual practice, I lose far more volume on the second 30 minutes of my boil than the first 30 minutes, which tells me that the boil off rate is not a linear value.

 

[TheZymurgist]

The pod cast that the article was written from is here: http://s125483039.onlinehome.us/archive/bs_melanoidin_7-19-08.mp3
If you want to get to the good parts:
12:15 to 28:40 they talk about flavors.
32: to 46:10 they talk about decoction vs. extended boil vs. ingredients.
48:00 + Boil off rates and at over 15% per hour, will everything taste like a boch? The answer is all equipment is different, but generally speaking, a vigorous boil caused by excessive thermal loading will create undesirable melanoidins.
25% is definitely too much.
20% with undesirable maltiness would indicate too vigorous of a boil.
By controlling the heat, you should be able to control the boil off.
Those guys shoot for no more than 15% per hour.

I use a turkey fryer burner that is not very adjustable.
I have noticed caramelization on the bottom of by BK in the shape of the flame.
Having had problems with what I will call a sickening sweet flavor, I can certainly see how those flavors could have been caused by melanoidins created by excessive thermal loading of the BK.

Listen to the pod cast and decide for yourselves.
I think cjgenever has brought up valid and important info. Thanks!

From the posts above, I think many would disagree that 25% is *definitely* too much. Again, I, and others, can't tell a difference in taste between my beers and those done on other systems with lower boil off rates.

My local club just did a Wee Heavy barrel project where 10 of us brewed the exact same recipe, and each batch was tasted before being put into the barrel. I didn't have any issues with attenuation or caramelization, and there was no noticeable taste difference between my batch and the other batches that were brewed, at least not relating to maillard reactions.

 

[Setesh]

Converted kegs, 5500 watt elements
~1.15 g/h at 70% duty cycle (gentle rolling boil)
~1.25 g/h at 75% duty cycle (vigorous rolling boil)
~1.40 g/h at 80% duty cycle (leaping boil)

 

[Safa]

And in actual practice, I lose far more volume on the second 30 minutes of my boil than the first 30 minutes, which tells me that the boil off rate is not a linear value.

Well that is logical. If you don't adjust you heat down through the boil, you are introducing the same amount of heat to a smaller volume of water, which would increase the vigor of the boil, thereby increasing boil off rate.


Sent from my iPhone using Home Brew

 

[danorocks17]

I lose about a gallon an hour

 

[acidrain]

From the posts above, I think many would disagree that 25% is *definitely* too much. Again, I, and others, can't tell a difference in taste between my beers and those done on other systems with lower boil off rates.

My local club just did a Wee Heavy barrel project where 10 of us brewed the exact same recipe, and each batch was tasted before being put into the barrel. I didn't have any issues with attenuation or caramelization, and there was no noticeable taste difference between my batch and the other batches that were brewed, at least not relating to maillard reactions.

You seem defensive.
Isn't a wee heavy supposed to have some mailard reactions? Recipes I'm seeing are for a 180 minute boil.
Maybe a better test would be with a Blond or a Pale Ale.


Personally, this is kind of an Ah Ha moment... I just ordered two new Banjo Burners.

 

[Hopper5000]

I have a bayou classic propane burner and a 15gal kettle. I boil off about 2.5 - 3 gal in that hour with a pretty aggressive boil.

 

[Setesh]

The pod cast that the article was written from is here: http://s125483039.onlinehome.us/archive/bs_melanoidin_7-19-08.mp3
If you want to get to the good parts:
12:15 to 28:40 they talk about flavors.
32: to 46:10 they talk about decoction vs. extended boil vs. ingredients.
48:00 + Boil off rates and at over 15% per hour, will everything taste like a boch? The answer is all equipment is different, but generally speaking, a vigorous boil caused by excessive thermal loading will create undesirable melanoidins.
25% is definitely too much.
20% with undesirable maltiness would indicate too vigorous of a boil.
By controlling the heat, you should be able to control the boil off.
Those guys shoot for no more than 15% per hour.

I use a turkey fryer burner that is not very adjustable.
I have noticed caramelization on the bottom of by BK in the shape of the flame.
Having had problems with what I will call a sickening sweet flavor, I can certainly see how those flavors could have been caused by melanoidins created by excessive thermal loading of the BK.

Listen to the pod cast and decide for yourselves.
I think cjgenever has brought up valid and important info. Thanks!

That is a great podcast. Before listening to that I had always thought the more vigorous the boil the better. Now I go for a rolling boil and that is it. I don't try to get the wort jumping up at me anymore. Scoop the foop before/during hot break and I can leave even a full kettle unattended without worry. Before if a cap developed on top of that raging boil it would boil over in a heartbeat so I had to watch it like a hawk, spray bottle in hand. I don't miss those days one little bit! Saving energy is a bonus too.

 

[max384]

Well that is logical. If you don't adjust you heat down through the boil, you are introducing the same amount of heat to a smaller volume of water, which would increase the vigor of the boil, thereby increasing boil off rate.


Sent from my iPhone using Home Brew

I do actually adjust the heat down a bit to keep a fairly constant boil. The bigger issue is there is a larger percent of surface area compared to volume in contact with the heat source (bottom of kettle) when there is less liquid in the kettle.

 

[TheZymurgist]

You seem defensive.
Isn't a wee heavy supposed to have some mailard reactions? Recipes I'm seeing are for a 180 minute boil.
Maybe a better test would be with a Blond or a Pale Ale.


Personally, this is kind of an Ah Ha moment... I just ordered two new Banjo Burners.

If I seem defensive, it's only because I'm defending against the spread of incorrect information that gets proliferated when someone listens to a podcast and latches on to one phrase or sentence and spouts it off as gospel, without taking into account the fact that the information they're spreading *might* be situational or anecdotal.

Whether maillard reactions are supposed to be a part of a recipe or not is irrelevant. By your statement that "25% is definitely too much" I would have had more caramelization the the rest of my brewing partners, wouldn't I have? So at what point do you take into account the fact that I didn't?

I brewed a saison over the summer with a 120 minute boil that saw three gallons of boil off. That's 1.5 gallons per hour for a five gallon batch. With an 8 gallon original boil volume, that's 37.5% boil off rate. If, like you said, "25% is definitely too much," I would have experienced noticeable caramelization and/or attenuation issues, of which I had neither.

The reason why my boil off is so high is that I'm using a 15.5 gallon keggle for 5 gallon batches. I have more surface area than most others that are using 8 or 10 gallon pots for the same size batch. If I were doing 2 gallon batches in a three gallon pot on my stove and getting boil off rates of 25% or more, then I might agree with you, that, in that situation, 25% is excessive.

My only point is to be careful of the information that is spread, as so much of what we do varies from system to system, and person to person. Try to avoid using hard-and-fast blanket statements, especially if it's out side of your experience. Remember, YMMV.

 

[Grannyknot]

If I seem defensive, it's only because I'm defending against the spread of incorrect information that gets proliferated when someone listens to a podcast and latches on to one phrase or sentence and spouts it off as gospel, without taking into account the fact that the information they're spreading *might* be situational or anecdotal.

Whether maillard reactions are supposed to be a part of a recipe or not is irrelevant. By your statement that "25% is definitely too much" I would have had more caramelization the the rest of my brewing partners, wouldn't I have? So at what point do you take into account the fact that I didn't?

I brewed a saison over the summer with a 120 minute boil that saw three gallons of boil off. That's 1.5 gallons per hour for a five gallon batch. With an 8 gallon original boil volume, that's 37.5% boil off rate. If, like you said, "25% is definitely too much," I would have experienced noticeable caramelization and/or attenuation issues, of which I had neither.

The reason why my boil off is so high is that I'm using a 15.5 gallon keggle for 5 gallon batches. I have more surface area than most others that are using 8 or 10 gallon pots for the same size batch. If I were doing 2 gallon batches in a three gallon pot on my stove and getting boil off rates of 25% or more, then I might agree with you, that, in that situation, 25% is excessive.

My only point is to be careful of the information that is spread, as so much of what we do varies from system to system, and person to person. Try to avoid using hard-and-fast blanket statements, especially if it's out side of your experience. Remember, YMMV.

Well said.

 

[Setesh]

I do actually adjust the heat down a bit to keep a fairly constant boil. The bigger issue is there is a larger percent of surface area compared to volume in contact with the heat source (bottom of kettle) when there is less liquid in the kettle.

I wonder if adjusting the heat down throughout the boil could cause noticeable inconsistencies from batch to batch. The theory being that unless you adjusted the heat to the same levels at the same times your process would be different. You might end up missing your end volumes, and therefor gravity, because your boil off changes from batch to batch. I can't see it being that big of a difference, just a thought.

 

[max384]

If I seem defensive, it's only because I'm defending against the spread of incorrect information that gets proliferated when someone listens to a podcast and latches on to one phrase or sentence and spouts it off as gospel, without taking into account the fact that the information they're spreading *might* be situational or anecdotal.

Whether maillard reactions are supposed to be a part of a recipe or not is irrelevant. By your statement that "25% is definitely too much" I would have had more caramelization the the rest of my brewing partners, wouldn't I have? So at what point do you take into account the fact that I didn't?

I brewed a saison over the summer with a 120 minute boil that saw three gallons of boil off. That's 1.5 gallons per hour for a five gallon batch. With an 8 gallon original boil volume, that's 37.5% boil off rate. If, like you said, "25% is definitely too much," I would have experienced noticeable caramelization and/or attenuation issues, of which I had neither.

The reason why my boil off is so high is that I'm using a 15.5 gallon keggle for 5 gallon batches. I have more surface area than most others that are using 8 or 10 gallon pots for the same size batch. If I were doing 2 gallon batches in a three gallon pot on my stove and getting boil off rates of 25% or more, then I might agree with you, that, in that situation, 25% is excessive.

My only point is to be careful of the information that is spread, as so much of what we do varies from system to system, and person to person. Try to avoid using hard-and-fast blanket statements, especially if it's out side of your experience. Remember, YMMV.

Although I agree with what you said, I'd be remiss if I didn't point out an error in your reasoning.

You said your boil off rate was 37.5%. That's actually a boil off amount, not a rate. A rate must be per unit time. Your rate would be only half of that per hour (18.75% per hour). The boil off rates, not volumes were what was being discussed, and what you were comparing yours too. So ultimately, you were comparing your 18.75% rate to 25% to prove that it was not excessive.

 

[max384]

I wonder if adjusting the heat down throughout the boil could cause noticeable inconsistencies from batch to batch. The theory being that unless you adjusted the heat to the same levels at the same times your process would be different. You might end up missing your end volumes, and therefor gravity, because your boil off changes from batch to batch. I can't see it being that big of a difference, just a thought.

I don't have much of a choice but to do that in order to avoid a boilover. I don't have any problems with missing my end volumes doing it this way. Although I obviously don't make the exact same adjustments and the exact same times, it's close enough not to make a noticeable difference in my brewing operation.

 

[TheZymurgist]

Although I agree with what you said, I'd be remiss if I didn't point out an error in your reasoning.

You said your boil off rate was 37.5%. That's actually a boil off amount, not a rate. A rate must be per unit time. Your rate would be only half of that per hour (18.75% per hour). The boil off rates, not volumes were what was being discussed, and what you were comparing yours too. So ultimately, you were comparing your 18.75% rate to 25% to prove that it was not excessive.

Good point, my math was wrong. It's a good thing I'm not an accountant...

 

[acidrain]

By your statement that "25% is definitely too much"

That's not my statement... just paraphrasing what was said in the pod cast.

The reason why my boil off is so high is that I'm using a 15.5 gallon keggle for 5 gallon batches.

Me too

My only point is to be careful of the information that is spread, as so much of what we do varies from system to system, and person to person. Try to avoid using hard-and-fast blanket statements, especially if it's out side of your experience. Remember, YMMV.

I qualified my post with "Listen to the pod cast and decide for yourselves", just like you qualified your post with "YMMV".

I love challenging the accepted rules. I do it all the time. You are doing it to me. I enjoy it.
There is no wrong or right way in brewing. There is only what works for you.

Honestly, this was the first time I've ever heard anything like that. I was sure we were all going to call shenanigans on cjgenever, but hey, turns out there is something to this. You can't deny there is something to it. Maybe it doesn't affect you, but it could, right?

 

[cjgenever]

I'd be interested in the citation as well. When I used propane I boiled off 1 gal/hr. With an electric keggle I'm a bit over 2 gal/hr. I don't think I've noticed a significant difference in finished product but did not save any from the same recipe batches for side by side comparison.

Citations are hard I got a lot of info from brew strong with Palmer and Zainasheff. I know there was an episode on melanoidins. I'm not sure what episode the boil off figures were mentioned.

Sent from my SCH-R970 using Home Brew mobile app

 

[619Brewer]

619brewer would you say you do a pretty vigorous boil?

Sorry for the delay, but no, I use a Banjo 10" burner cranked up all the way to get it to around 200 degrees F then I turn it as far down as I can get away with and still have a rolling boil. I have a big ass pot and I live in Southern Cali.

 

[Hamaki]

Citations are hard I got a lot of info from brew strong with Palmer and Zainasheff. I know there was an episode on melanoidins. I'm not sure what episode the boil off figures were mentioned.

Sent from my SCH-R970 using Home Brew mobile app

Because of lousy internet I can't do video very well but I did do some on line searching and found some info that supports what you say and some seemingly conflicting info as well. I was not able to find the 15% rule, however.

In order to be as consistent as possible I crank my pwm controlled 5500 W element all the way up for a boil and lose just about 9 quarts in 60 minutes out of my keggle. I start with 8 gallons so that's a little over 28% boil off. This is a vigorous boil but not jumping. I think I'll try setting the control to just maintain a mild rolling boil and do a test boil on water to figure loss, hopefully not more than the 15% target. Then I'll repeat my last couple of batches (the IPA currently keg conditioning & the hef in primary) so I can do a side by side taste test.

 

[sigurdur]

Hmmm it gave me 1.85 gph. Not sure I've seen that yet. I am still trying to dial in my kettle and such but I thought last time I lost just under 1.5 but maybe I am wrong and therein lies some of my issues.

My kettle is 1.00mm thick and 18" in diameter. I use propane.

Hey man.
I wrote this calculator .. and it sure does a lot of assumptions. It's meant for easy "go-to" figure, but not a be-all end-all calculator.

There are a lot of factors that come into play with how much you boil off per hour:
1. Relative Humidity in the air around you
2. Boil vigor (how much the liquid moves around, this ties into the input power of your system)
3. Air vigor (how well the humidity escapes from the pot)
4. Altitude/Air pressure in the ambient air

And as far as maillard reactions go, you can reduce the boil-off by reducing the opening of the pot but the maillard reactions will remain the same.

The calculator assumes a lot and gives you a simple number that should be around the actual boil-off, but not always dead-on.

So, to try to give you a simple answer:
If your experience is that your system boils off 1.85 GPH, then that's how your system is .. no shame in that
I would only reduce the input power (opening on the propane tank) if your boil is very vigorous. If it is not vigorous, there may be other external factors that increase your boil-off rate (maybe RH%?)

Good luck!

 

[cjgenever]

Because of lousy internet I can't do video very well but I did do some on line searching and found some info that supports what you say and some seemingly conflicting info as well. I was not able to find the 15% rule, however.

In order to be as consistent as possible I crank my pwm controlled 5500 W element all the way up for a boil and lose just about 9 quarts in 60 minutes out of my keggle. I start with 8 gallons so that's a little over 28% boil off. This is a vigorous boil but not jumping. I think I'll try setting the control to just maintain a mild rolling boil and do a test boil on water to figure loss, hopefully not more than the 15% target. Then I'll repeat my last couple of batches (the IPA currently keg conditioning & the hef in primary) so I can do a side by side taste test.

The podcasts are available. I downloaded most of them over my cell phone network with poor reception. No video, just audio.

Sent from my SCH-R970 using Home Brew mobile app

 

[The_Glue]

I think my boil-off rate is around 50% with 90 minute boils. Is that means that the amount of salts gets doubled in my finished water? Is it possible that my starting amount of 40mg/l Magnesium perhaps can get too high by the end of the boil? (80mg/l)

 

[aqualung23]

I brew outside, so it varies. I'd say about a gallon an hour for a vigorous boil in mild temperatures. But when I brewed last weekend on a windy 35 degree day, I boiled off almost 2 gallons in an hour.