Element duty cycle - What do you run at?

I just listened to a BN podcast where Jamil and Tasty say that most homebrewers boil too vigorously, much more than they need to. So today I did an experiment. I normally boil at 70% duty cycle on my 5500 watt element in a converted keggle with 2 layers of reflectix insulation and get 1.25 gph boil off. Today I tried a 60% duty cycle and got about the same boil off at 1.20 gph. Then I tried 50%, this got me 1.1 gph. 40% gave me .9 gph boil off which is quite a big difference. I was amazed that I still got a good rolling boil at 40%. It wasn't leaping around, but it was definitely rolling. When I went to 30% I only got a rolling boil for a second or so after the element fired and the rest of the cycle it was just a simmer so 40% is the lowest I can really go on my system. But, if I can get my boil off down rate down from 1.25 gph to .9 gph then I am all for it. I only ran at 70% before because that's what Kal did and I assumed I should do the same. I'm going to brew tomorrow and will try 40% and see what the results are. Maybe using wort instead of plain water will make a difference?

So, what duty cycle do you run? Have you experimented with different duty cycles and if so did you notice any difference in your finished beers?

I do a 13 gallon boil to get down to 11.5 gallon in a 16 gallon pot, 43 % gives me a boil off rate of 1.5 over the 60 minutes

after the hot break I have been dialing it back to that it gives me a nice rolling boil but not to crazy

all the best

S_M

This is a great question Setesh. Did you by chance record your temperatures? The third paragraph here somewhat addresses affecting flavor: http://www.howtobrew.com/section1/chapter7-2.html

Though in theory, a full boil will be at the same temperature as a rolling boil, you just change the amount of water evaporation.

Sent from my Nexus 7 using Home Brew mobile app

I have been setting my boil element at 60% with 13 gallons & and a 5500watt camco.

Sent from my EVO using Home Brew mobile app

bonebrews said:

This is a great question Setesh. Did you by chance record your temperatures? The third paragraph here somewhat addresses affecting flavor: http://www.howtobrew.com/section1/chapter7-2.html

Though in theory, a full boil will be at the same temperature as a rolling boil, you just change the amount of water evaporation.

Sent from my Nexus 7 using Home Brew mobile app

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My PID only shows whole numbers, so 212 is that I got at every setting.

Setesh said:

I just listened to a BN podcast where Jamil and Tasty say that most homebrewers boil too vigorously, much more than they need to.

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Did they say what the problem is with too vigorous of a boil?

I run around 63% on my 5500 watt camco keggle. I think that is around 1.1 gph.

I don't use a PID, I use a PWM controller. I start at max power then based on the knob position I settle in at about 45%.

I've never had issues with possibly boiling too vigorously. I think what they're saying is that it's simply wasted energy/loss?

Setesh said:

I only ran at 70% before because that's what Kal did and I assumed I should do the same.

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I run at 85% and with a 60 min boil I start with 13.9 gallons and end up with 12 gallons.

I do do a vigorous boil. Is there a less vigorous boil I could use? Maybe. I haven't done any tests at lower duty cycles to see at which point I may start having issues (proteins not coagulated as much as they could, not driving off enough unwanted volatile compounds, hop alpha acid extraction not maxized, etc).

But my question is why? What's the savings? If you have a boil kettle that's on the small side and you want to reduce your boil off rate then it maybe worth looking into.

Cost savings is negligible where I live ($0.12/kWh electricity rate which is also the average US national rate). Boiling for 60 mins at 85% at $0.12/kWh costs me 56 cents. I could maybe save 20 cents if I greatly lower the duty cycle. So not worth it for most people on the cost savings front.

Kal

kevink said:

Did they say what the problem is with too vigorous of a boil?

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They thought that it would change the flavor through more melanoiddin production, harsher bitterness from the hops, on top of wasting lots of energy.

I'm with Kal on this one with respect to energy savings. With electric brew systems it's a non-issue, but with propane it becomes more of an issue. I don't think those guys use or have regularly used electric systems (at least they never talk about it and I haven't listened to an episode in a while), so maybe the big thing for them is energy savings.

Did Jamil and Tasty give any specific examples of brews they did where they noticed off flavors due to too vigorous of a boil? Were any experiments done or is it just a hunch of theirs? Those guys are great and they know a lot about brewing, but they sometimes have opinions that they don't substantiate.

Did they explain the hop bitterness thing? I mean, an easy boil and a really vigorous boil are the exact same temperature, so they are implying that the harsh bitterness is due to more hop movement in the BK. That seems strange to me. Maybe I should just listen to the episode. Do you know which episode it was?

kal said:

There are no issues that will be caused by boiling too vigorously. I think what they're saying is that it's simply wasted energy/loss.


I run at 85% and with a 60 min boil I start with 13.9 gallons and end up with 12 gallons.

I do do a vigorous boil. Is there a less vigorous boil I could use? Maybe. I haven't done any tests at lower duty cycles to see at which point I may start having issues (proteins not coagulated as much as they could, not driving off enough unwanted volatile compounds, hop alpha acid extraction not maxized, etc).

But my question is why? What's the savings? If you have a boil kettle that's on the small side and you want to reduce your boil off rate then it maybe worth looking into.

Cost savings is negligible where I live ($0.12/kWh electricity rate which is also the average US national rate). Boiling for 60 mins at 85% at $0.12/kWh costs me 56 cents. I could maybe save 20 cents if I greatly lower the duty cycle. So not worth it for most people on the cost savings front.

Kal

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That's true, the cost savings is negligible. But as you pointed out it can make sense for smaller vessels. I'm using keggles and to do a 1.5 hour boil for a 12 gallon batch I had to have 14.5 gallons in the boil kettle. The lower my BOR the lower the pre boil volume and the easier it is to manage.

kevink said:

I'm with Kal on this one with respect to energy savings. With electric brew systems it's a non-issue, but with propane it becomes more of an issue. I don't think those guys use or have regularly used electric systems (at least they never talk about it and I haven't listened to an episode in a while), so maybe the big thing for them is energy savings.

Did Jamil and Tasty give any specific examples of brews they did where they noticed off flavors due to too vigorous of a boil? Were any experiments done or is it just a hunch of theirs? Those guys are great and they know a lot about brewing, but they sometimes have opinions that they don't substantiate.

Did they explain the hop bitterness thing? I mean, an easy boil and a really vigorous boil are the exact same temperature, so they are implying that the harsh bitterness is due to more hop movement in the BK. That seems strange to me. Maybe I should just listen to the episode. Do you know which episode it was?

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I'll try to go back and figure it out. It was one of the Brewing With Style episodes where they were cloning another beer and they went off on a rant. I don't remember them referencing any specific studies or experiments or talking about comparisons though. It may just have been a hunch.

kal said:

I've never had issues with possibly boiling too vigorously. I think what they're saying is that it's simply wasted energy/loss?


I run at 85% and with a 60 min boil I start with 13.9 gallons and end up with 12 gallons.
Kal

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Sorry, I could have sworn it was your videos that I got that starting number from, it must have been someone else. I wish I would have bought boilermakers like you but I tried to save some money and go with recycled kegs. They work but not well for larger batches with long boils. I do absolutely love having your panel though!

Setesh said:

That's true, the cost savings is negligible. But as you pointed out it can make sense for smaller vessels. I'm using keggles and to do a 1.5 hour boil for a 12 gallon batch I had to have 14.5 gallons in the boil kettle. The lower my BOR the lower the pre boil volume and the easier it is to manage.

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Now that's a benefit I can agree with. The last batch on my old system which used a keggle was a 14.5 gallon pre boil volume. Not fun!

kevink said:

Now that's a benefit I can agree with. The last batch on my old system which used a keggle was a 14.5 gallon pre boil volume. Not fun!

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That's right up to the rim!

I throttle back my elements after reaching hot break as my kitchen extraction system can't keep up with 100% boil and quickly becomes a beer-flavoured sauna ...

As crazy as it sounds, I sometimes think I should have gone with 30 gallon Boilermakers for 12 gallon post-boil batches. If I'm boiling for 90 mins I'm at just under 15 gallons pre-boil and with all the foam at hot break, with my 20 gallon kettles I have to continuously stir it sometimes for ~10 mins straight until it drops. With 30 I probably wouldn't have do anything. Is that just being lazy?

Kal

kal said:

As crazy as it sounds, I sometimes think I should have gone with 30 gallon Boilermakers for 12 gallon post-boil batches. If I'm boiling for 90 mins I'm at just under 15 gallons pre-boil and with all the foam at hot break, with my 20 gallon kettles I have to continuously stir it sometimes for ~10 mins straight until it drops. With 30 I probably wouldn't have do anything. Is that just being lazy?

Kal

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Maybe, but I agree that I wouldn't want to have to do it. That seems like a perfect reason to lower you duty cycle. The more heat you put in the more it's going to try to boil over. Just like the propane guys, turning down the heat until it calms down works great. A few drops of foam cap will solve it too, that stuff works great.

From a physics standpoint, assuming an actual boil and not a simmer the boil will be at 212F, not higher or lower.
Does the increased agitation of a vigorous boil do anything that a gentle boil doesn't? The oils, proteins and such should be affected by the temperature, pH and other chemical factors but shouldn't be affected by the physical agitation of the boil. Has anyone noticed different? Has anyone looked into it? Does the more vigorous boil produce more foam/break?
It appears that once a boil is reached, you can dial your burner up or down to change the rate of boil off or to (marginally) save some electricity, but what else do you get?

Ayuir said:

From a physics standpoint, assuming an actual boil and not a simmer the boil will be at 212F, not higher or lower.
Does the increased agitation of a vigorous boil do anything that a gentle boil doesn't? The oils, proteins and such should be affected by the temperature, pH and other chemical factors but shouldn't be affected by the physical agitation of the boil. Has anyone noticed different? Has anyone looked into it? Does the more vigorous boil produce more foam/break?
It appears that once a boil is reached, you can dial your burner up or down to change the rate of boil off or to (marginally) save some electricity, but what else do you get?

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I thought the rolling action on the surface helped to volatilize certain compounds and that was the whole point of the rolling boil.

Well, I gave up on finding Jamil's comments on the downside of too vigorous a boil after going back through several episodes. But today as I listened to the 11-05-06 episode of the Sunday Session Mitch Steele (head brewer at Stone) talks about how they had to modify their recipes when they moved to their new system because the boil was so much more vigorous. He said they had to reduce their bittering hops because they got more extraction out of them due to the vigor of the boil. He said they had to move to more hopping in the whirlpool or dry hopping to get more flavor and aroma since they volatilized more of those compounds during the boil.

Yup, every setup is different so you often have to compensate. For example, homebrewers might hear that a commercial brewer adds hops at flameout and think they should do the same, but on the commercial level the hops will often steep for 20+ mins while they whirlpool because the system is so big. So a flameout hop on one commercial system may be more like a 20 min addition on the homebrew scale. It's all relative to the system.

Kal

Our first brew, we boiled at 45-50% duty. This resulted in less boil off than we originally accounted for so we missed our gravity, but the beer overall turned out awesome. The second brewday, we dialed it up to 75% duty, saw significantly more boil off, but nearer to the numbers we had in Beersmith for the recipe we designed.

Boiling is boiling, I think as long as you nail down the boil off number so you hit your OG, you're probably in fine shape.

Regarding Kettle Size: I regret choosing 15g Blichmanns for my system (intended to do 5g brews initially), should have gone to 20 immediately. Live and learn, we'll run these for now and likely upgrade to larger down the road.

hunter306 said:

Regarding Kettle Size: I regret choosing 15g Blichmanns for my system (intended to do 5g brews initially), should have gone to 20 immediately. Live and learn, we'll run these for now and likely upgrade to larger down the road.

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Same here. 20s are my next upgrade for sure.

hunter306 said:

Regarding Kettle Size: I regret choosing 15g Blichmans for my system (intended to do 5g brews initially), should have gone to 20 immediately. Live and learn, we'll run these for now and likely upgrade to larger down the road.

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I to purchased smaller kettles from the jump... However I am near the end phase of the exact Kal electric build, only exception is I have 55 Gallon Blichmans, as will as Large Nano March Pumps instead of the recommend size. Using these with the 50A panel, with 2 x 5500 Watt heaters..

Going to be interesting...