When Not Enough Power Is Still Plenty.

[Thirsty Boy]

I brewed a double batch of pilsner today - 50L pre boil volume. It took about 20 - 30 mins after i hit volume to get it boiling. I continuous sparged for about 75mins and the mash was brought to a mashout before sparging began.

And here's a video to show that you dont need to point the arse end of a Saturn V at your kettle in order to be able to brew a bigger batch. I have no choice - only 10A available for me to use in my brewery. But i manage to run an all electric brewery on that. 2400W is plenty for a single & just enough for a double - if you are willing to be a little patient about heat up times.



Ended up boiling off at about 8% per hour which is bordering on too low, but I always boil for 90mins anyway, so that makes up for a bit of it. And as you can see from the picture, with something floating in the boil to cut the heat loss a bit, the vigor of the boil was fine. It did tend to drop back to an insipid simmer without the floaty though.

So, no need to go for massive amounts of grunt if you mainly brew singles and only want to flirt with bigger batches every now and again - you can make do with a lot less than you might think.

 

[RdeVjun]

And here's a video to show that you dont need to point the arse end of a Saturn V at your kettle in order to be able to brew a bigger batch.

Ok, so no Saturn V for the doubles- we're all in complete agreement. What about a Saturn 1 then?

I only jest! As is the norm, a helpful and informative post TB! :icon_cheers:

 

[QldKev]

So with the single 10amp socket for a 50L you hit minimal boil off using floaties on top of the pot. Maybe if the element was deeper in the boil and a few more kw you may have hit a good boil off rate; rather than boiling just the surface layer? You post a lot of good stuff on here from your experience at the brewery; but I miss understanding this one.

 

[argon]

Thanks for the assurance TB. I'm looking at adding a 2200w element to my kettle to maintain the boil. I too am limited to 10amp. I do double batches with 41L preboil with a pre-ferment top-up.

I'll still have the rambo on stand by for ramping up to boil to cut the ramp times, then when boiling have the element take over. Feels like a good compromise of time and efficiency.

I assume you're using an immersion element like this one 2400w immersion which reaches to the bottom of the pot and boils the entire volume of the wort.

 

[Thirsty Boy]

So with the single 10amp socket for a 50L you hit minimal boil off using floaties on top of the pot. Maybe if the element was deeper in the boil and a few more kw you may have hit a good boil off rate; rather than boiling just the surface layer? You post a lot of good stuff on here from your experience at the brewery; but I miss understanding this one.

Actually, the element is resting about half a centimeter off the bottom of the pot, the entire volume of the liquid from top to bottom was boiling with good bubble formation and great wort velocity with a terrific rolling pattern from the offset heat source. The boil was minimal only in its evaporation rate - which would be a concern for driving off volatiles, except that it was minimal at around 8% per hour, but not actually inadequate.

So, you did misunderstand this one - i wasn't saying that you could make a pot boil with a single element, but its not really any good - I was saying that you can make 50L boil with a single 2400W element and with the exception of getting there slowly, it can be made to give a boil that is satisfactory (although admittedly slightly below optimum IMO) in every way.

So while if you were regular double batch brewer, i would think you were making a rod for your own back by trying to do it with just one element, you would only be making your life hard rather than compromising your beer quality. And so i personally wouldn't waste money on a big heat source when i do mostly single brews and only occasional larger batches.


Argon - as i said above. Works, works properly, but not optimally. And i dont know that the difference between 2400W and 2200W might not be the difference between works and doesn't work. Absolutely sure 2400W is OK for single batches - for doubles, if thats what you are doing all the time - i'd get more grunt. Although, if you are limited to 10A i suppose you dont have a choice.

 

[Maxt]

I use a 50L keggle and find that 2 x 2400 elements gives me serious boilover, so I usuualy use both to get to a boil, and then cut it to one for the rest of the time.

I have also been lucky in that the last 4 places I have lived have all had sheds that coped well with 2, 2400w elements, various fridges and lights running at the same time.

 

[QldKev]

Actually, the element is resting about half a centimeter off the bottom of the pot, the entire volume of the liquid from top to bottom was boiling with good bubble formation and great wort velocity with a terrific rolling pattern from the offset heat source. The boil was minimal only in its evaporation rate - which would be a concern for driving off volatiles, except that it was minimal at around 8% per hour, but not actually inadequate.

So, you did misunderstand this one - i wasn't saying that you could make a pot boil with a single element, but its not really any good - I was saying that you can make 50L boil with a single 2400W element and with the exception of getting there slowly, it can be made to give a boil that is satisfactory (although admittedly slightly below optimum IMO) in every way.

So while if you were regular double batch brewer, i would think you were making a rod for your own back by trying to do it with just one element, you would only be making your life hard rather than compromising your beer quality. And so i personally wouldn't waste money on a big heat source when i do mostly single brews and only occasional larger batches.


Argon - as i said above. Works, works properly, but not optimally. And i dont know that the difference between 2400W and 2200W might not be the difference between works and doesn't work. Absolutely sure 2400W is OK for single batches - for doubles, if thats what you are doing all the time - i'd get more grunt. Although, if you are limited to 10A i suppose you dont have a choice.

Now I get it; thanks for posting the extra info. :beer:

QldKev

 

[bear09]

I have found this very interesting.

My 2400w immersible gets 30L just to a rolling boil - JUST. By the time it has evapped a bit it gets going.

Perhaps the plastic lid on top really helps? I could not tell from the video if that pot was insulated - was it?

For me 2400w is barley enough to get 30L up and running let alone 50 - well done.

 

[raven19]

Great thread TB.

I am able to use a 3600W immersion with my 15A plug in the shed - but your info above is good to know nonetheless.

 

[Thirsty Boy]

I have found this very interesting.

My 2400w immersible gets 30L just to a rolling boil - JUST. By the time it has evapped a bit it gets going.

Perhaps the plastic lid on top really helps? I could not tell from the video if that pot was insulated - was it?

For me 2400w is barley enough to get 30L up and running let alone 50 - well done.

The pot is lightly insulated (silvered bubble wrap) and absolutely the lid floating on top is there to make it work. Its is a pretty insipid boil even in 30L without it.

I am using the food grade bucket lid - but i think it was manticle recently pointed out that a tinfoil baking tray would do the same job and remove the plastic in the boil foodgrade question completely. I am on the lookout for a big pie tin next time i m in the supermarket. Anything that can take the heat, floats and can cut down the surface area of the pot will do the trick.

 

[jonocarroll]

I am using the food grade bucket lid - but i think it was manticle recently pointed out that a tinfoil baking tray would do the same job and remove the plastic in the boil foodgrade question completely. I am on the lookout for a big pie tin next time i m in the supermarket. Anything that can take the heat, floats and can cut down the surface area of the pot will do the trick.

I have a couple of questions regarding your ingenious lid method (gladly attributed to you, I've not seen anyone do this before I saw this):

- Do you still aim for/get the same boiloff/hr that you might expect without the lid, or do you compensate?
- Do you predict the same or less driving off of unwanted volatiles?
- Do you find a lot of hop material getting stuck on the lid?

Purely out of curiosity. Sounds like a great way to get some more boil efficiency (in minimisation of losses) out of a system, provided the above aren't a problem.

 

[Thirsty Boy]

No, you dont get the same boil off, that of course is why (i think) it works. Cuts down the heat losses due to evaporation at the surface, leaves that spare heat to contribute to direct vaporization at the heat source and therefore to boil vigor. Also concentrates the "flow" of the bubbles and convection through a smaller area (not so much with a small point heat source like an immersion element though) which increases wort velocity/vigor. The evaporation doesn't even out though and i get quite a bit less total liquid loss than an equivalent boil vigour with more energy, or even from the dogey simmer that happens without the floaty.

I primarily use it as a tool to allow me to cope with my non-adjustable heat source, but do and have advocated something along these lines to cut down the heat flux through high surface area kettles, which normally need a really grunty heat source to get a decent rolling boil. Basically, it allows you to boil with less energy going into the system, and less energy travelling through your wort is better for beer quality. To a point of course.

You do need to make sure that you are still getting the minimum required evaporation to drive off volatiles - ergo checking to make sure that you are still evaporating between 8 & 15% of your starting volume per hour. If you are doing that, even on the low end, you are doing enough. Naturally a lid on the pot would do much the same thing - but because with a lid you have an issue with volatiles refluxing back into the pot, the combo of that with significantly reduced total evaporation is a definite potential area for quality issues. The floater however, lets you cut down the evap & thefore heat required to boil, but ensures that what gets boiled off stays boiled off. And you can also see whats going on in there and its easy to make additions, skim off gunk if you want to etc etc.

A bit of protien goo and some hops do get stuck to it, not too bad though. The bucket lid is a crappy option because it has all sorts of nooks and crannies - a nice smooth surface would be easy though. I boil for 90 mins, so i tend to give the lid a rinse under the tap to get off any googe thats built up before i throw in my hops at 60min - then they dont stick very much at all.

Its not ideal, it is a decent workaround for the fact that homebrew kettles mostly dont have great geometry though. Works for my situation.

 

[jonocarroll]

Its not ideal, it is a decent workaround for the fact that homebrew kettles mostly dont have great geometry though. Works for my situation.

Looks like given that you've addressed the main issues, it's actually pretty darn great. The pie pan might be one step better (as you've said, removing the plastic issue, plus being lightweight it will not require too much energy to heat the pan vs the lid, not that it's a large concern over the total energy input).

I'd say it's giving a better roll than my 4-burner. 'On ya.

 

[MarkBastard]

TB, does this only work when something is floating on the surface? I take it it's not the same as having the lid half on the pot?

 

[Fourstar]

I am on the lookout for a big pie tin next time i m in the supermarket. Anything that can take the heat, floats and can cut down the surface area of the pot will do the trick.

Ikea pizza tray should do the trick.

 

[Thirsty Boy]

TB, does this only work when something is floating on the surface? I take it it's not the same as having the lid half on the pot?

Floating on the surface Seems to work best - but to be honest i havent done much full scale brewing with lids partially on.

I have done small scale trials, and while a lid partially on (tested through to almost all the way on) helps, it doesn't seem to help "as much" and then you have the reflux issue too. I have no doubt you could probably sort something out with a normal pot lid, and its probably the easiest thing to try first. Just make sure you remain well inside the 8-15% boil off range and even a bit of reflux wont be much of a problem.

For me floating something on the surface seems easier and more intuitively "right" and my brewery is kind of cramped, so not having a square foot or so of lid hanging off the pot and taking up standing room is important too.

Just another alternative - not like its the new "right" way to manage your boil or anything.

 

[MarkBastard]

The reason I ask is because I'm thinking I wonder if you could have a lid that looked like an upside down funnel, so the surface area is considerably lower than the pot width. Obviously the boil-off should be reduced, the loss in heat should be reduced, but the bad compounds you'd think should still boil off?

Then if you wanted to maybe you can attach a hose and fan to the opening to extract the air directly outside.

And if you could vary the speed of the fan, could you vary the amount of boil off?

Just thinking out lout really

 

[Thirsty Boy]

The reason I ask is because I'm thinking I wonder if you could have a lid that looked like an upside down funnel, so the surface area is considerably lower than the pot width. Obviously the boil-off should be reduced, the loss in heat should be reduced, but the bad compounds you'd think should still boil off?

Then if you wanted to maybe you can attach a hose and fan to the opening to extract the air directly outside.

And if you could vary the speed of the fan, could you vary the amount of boil off?

Just thinking out lout really

Just the same as you get when you cut a hole in a keg shaped kettle - hole considerably narrower than the body of the boiler. And yep, it helps a decent bit.

Make a drawing of what you just described - and you will have pretty much drawn a picture of a stock standard domed top or cone topped boil kettle that you can see in any commercial brewery. So i kind of suspect it wold work very well indeed.