New kettle—didn't quite get to boil on stovetop

[Coolhand78]

Hi guys – Relatively inexperience brewer here (approx. 6 extract batches), looking to do my first BIAB. I recently got an 8gallon aluminum pot, and today I decided to do a test boil to build up an oxide layer and also have an idea of my boil off rate.

Well, it didn't go exactly as planned. I never quite reached a full boil. I started with 7 gallons in the pot, and I had the water up to 160 degrees within 30 minutes. At this point I was feeling pretty good; my gas stove has a 16,000 BTU "power burner" on it, and I figured I'd be able to get to a full boil in no time. However, 90 minutes later (2 hours total) I could only get the water up to 210, just on the edge of becoming a boil. I even put the lid on (partially), but that barely seemed to help.

Has anyone else dealt with this? Is it possible that a gas burner, running on full blast, can only get water up to a certain temperature without it ever getting any hotter? If I had continued to wait, would it have eventually reached boiling?

Any advice would be much appreciated. For various reasons, I prefer being able to brew in my kitchen and am not really looking to get an outdoor propane burner.

Thanks in advance!

edit: stove has 16,000 BTU, not 12,000.

 

[Gnomebrewer]

7 gallons would be outside the capability of most kitchen cook-tops. My three ring gas burner is about 35000btu and just maintains a boil with 8-9 gallons.

Basically, as the temperature of the water increases, the temp difference to the surrounding air increases resulting in greater heat loss to the environment. When the heat input (gas burner) matches the heat output (heat loss) you are at a sticking point. Also, extra energy is required to go from 212F (not boiling) to 212F (boiling) as it takes energy to change phase.

The solution - 1) higher output burner 2) Less water 3) insulate the kettle to prevent heat loss (this could be dangerous though as the flame from the burner could melt/burn the insulation material) 4) use electric elements

 

[troy2000]

When I was using a stove top, I straddled two gas burners with my boil kettle. Even though the kettle only reached to about the middle of each burner, it heated much faster than a single burner, and maintained a rolling boil with no trouble.

But my 8 gal kettle is as wide as it is tall, rather than being tall and narrow like a stockpot; I don't know what yours is shaped like.

Caution: if you have a porcelain stove top, you might want to lay down a layer of aluminum foil to protect the finish from the flames, just in case. It probably isn't necessary, but wives have probably killed for less than discolored porcelain...

 

[pricelessbrewing]

Already replied to your post on reddit, but for consistancy:

Depending on how wide your pot is, that's definitely possible.

You could look into getting or buying a small heat stick. I bought two of the ones below, my time to boil from ~130F was like 75minutes or so for 6~ gallons. Did a test run two nights ago with cold tap water (70~) and go to boil is about 40 minutes. Was about 3-4 degrees per minute, was super fast and I only had 1 plugged int. I suspect if I use both, I'll be at boil within 20 minutes easy. At the time they were only 6.79$ each. I would recommend waiting and buying at least one of these when the price drops again.

http://www.amazon.com/dp/B00FO8FY68/?tag=skimlinks_replacement-20

Should note, my stovetop is electric and while able to get to a full boil on its own for 6-6.5G of water it took way too long for my liking.

 

[Coolhand78]

Hmm, this is pretty disappointing. I was thinking that my gas stove is pretty new and could handle some decent size BIAB. I'm not sure my kettle is wide enough to reach the middle of the both the front and back burner. It's 14" wide and 12.75" high.

My water volume evaporated/steamed down to 5 gallons, but it still wasn't boiling. So, let's say I can only boil up to 4 gallons on my stove. What could be the largest batch size I could do? Approximately 3-3.5 gallons into the fermenter? Is there any way I can still brew a "big" beer?

 

[Coolhand78]

Interesting. I am not familiar with those. Do you use it (in addition to the stovetop burner) for the duration of the boil, or just to help bring it up to boil and from there the stove can maintain the boil?

Already replied to your post on reddit, but for consistancy:

Depending on how wide your pot is, that's definitely possible.

You could look into getting or buying a small heat stick. I bought two of the ones below, my time to boil from ~130F was like 75minutes or so for 6~ gallons. Did a test run two nights ago with cold tap water (70~) and go to boil is about 40 minutes. Was about 3-4 degrees per minute, was super fast and I only had 1 plugged int. I suspect if I use both, I'll be at boil within 20 minutes easy. At the time they were only 6.79$ each. I would recommend waiting and buying at least one of these when the price drops again.

http://www.amazon.com/dp/B00FO8FY68/?tag=skimlinks_replacement-20

Should note, my stovetop is electric and while able to get to a full boil on its own for 6-6.5G of water it took way too long for my liking.

 

[The Pol]

Sadly, it only takes about 11,000 BTUs to maintain a solid rolling boil for a 5 gallon brew.

Gas is just very ineffective, as much of the output is simply lost to ambient. The energy isn't well utilized. Gas burners on a kettle, are about 30% efficient. To get 11,000 BTUs into that kettle, you need to start at 33,000 BTUs at the burner.

 

[Coolhand78]

It makes me curious as to why so many people said I should get a ten gallon pot for stovetop biab. I only got an 8 gallon because of size constraints. Otherwise, I definitely would have got a 10 gallon. This makes it hard for me to believe that batches any larger than 2.5 gallons are even possible on stovetop.

 

[The Pol]

Think about this.

It takes 970 BTUs to create a single pound of steam. If you want to boil off a gallon of water in one hour, that is 8.34 pounds of steam. That alone is 8,000 BTUs. If your stove is 12,000 BTUs, and gas is very inefficient at heating due to losses to ambient, you will be hard pressed.

You are probably netting 4,000 BTUs, give or take. Meaning that you will evaporate about .5 gallons per hour, and never have a vigorous boil.

It's all math.

You'd only need 3500W of electricity to boil off that gallon in one hour, because it releases 100% do it's energy to the wort.

 

[pricelessbrewing]

Without using additional heat sources-
The short answer is, you're limited to your preboil volume as the maximum amount your stove can boil. If your store can only boil 4 gallons, then you're limited to 4-boil off.

The long answer is, you can get away with topping off with boiling water gradually from a small pot, but hop extraction may be limited to 80~ or so.
Example: boil off is .75 gallon. Max boil is 4 gallons. Pre boil starts at 4, then every 15 minutes you add (0.75/4) of already boiling water.

I used the one in addition to the stovetop. I would consider using it as the main source but it's cheap and has bad chrome paint that flakes off the first time you use it and it seems to be slightly higher watt density and will probably die a lot faster that way and the stove can maintain.

If I needed to maintain the boil, and had a gas stove, and lived at a house instead of the apartment, I would run a 220v outlet with 20amp gfi protection and use a single 3500-4500w element and go all electric. Or two elements to go to boil and one to maintain.

 

[Yooper]

It makes me curious as to why so many people said I should get a ten gallon pot for stovetop biab. I only got an 8 gallon because of size constraints. Otherwise, I definitely would have got a 10 gallon. This makes it hard for me to believe that batches any larger than 2.5 gallons are even possible on stovetop.

It depends on your stove. My "professional" burner on my stove can boil 6.5 gallons, although it takes a while to get to a boil, while other people struggle to boil 3 gallons.

Try boiling water again, and when you know the maximum your stove can boil, you can decide then to either live with smaller batch sizes, or calculate the recipe to allow for topping up with water. Lots of brewers have to do things like that to boil on their stove top. Others go outside with a turkey fryer burner because they can't boil on their stove. There are lots of choices here!

 

[Coolhand78]

Well I feel like an idiot, thinking that my gas stove was more capable than it really was. I guess I might be limited to 3G batches. Not sure I really needed to get this 8G kettle when I had a perfectly good 5G one. Hopefully I still can make some good all grain batches, and if I want to do something with a higher gravity, do PM and help it out with some DME.

Thanks everyone for taking the time to give input. If there is anyone else with advice for noobs going BIAB, it's much appreciated. Thanks!

 

[Black Island Brewer]

There is a possible solution that is elegantly simple. I saw this on a large scale right here on HBT but I can't find it now. You could fashion a simple skirt around the outside of the kettle out of sheet metal or aluminum. It would be open at the bottom, closed at the top, and leave maybe a quarter to a half inch of space between it and the kettle. The heat going up the sides of the kettle would by trapped in inside the skirt, providing additional heat from the sides of the kettle.

I wish I could find that thread. The guy even had a video.

 

[Black Island Brewer]

I found it!

The distance is to the bottom of the chine.

To capture all of the heat you must make sure that the skirt is below chine. I added bolts to the chine to lift the keggle slightly. To cut holes accurately make a paper template first so there is no guessing.

Since using the pot skirt I don't have to turn the burner up very much at all. In fact I have to lower it quite a bit once it gets boiling. Also during flame out hop additions there is still a lot of heat in the keggle that I have to remove the welding blanket or it will keep simmering.

Here is a video of the boil, with the burner turned way down.

http://s94.photobucket.com/user/purple11haze/media/20130810_182016_zpse5864033.mp4.html

I think this could get you the boil you're looking for!

 

[TexasWine]

I BIAB 5 gallon batches on a cook top in a 9 gallon Bayou Classic pot. My pre-boil volume ranges from 6.5 to 7.5 gallons, depending on the boil length.

Just checked the specs, and the “power” burner I use on the cook top is rated for 17,000 BTU/hr. With that I can maintain a very rigorous boil and actually can’t run that burner full tilt due to boil over risks. But to bring things up from mash to boiling temps I straddle two burners like another poster mentioned for a total of about 23,000 BTU/hr. It doesn’t take much time to get from 150°F to boiling.

Addressing the need for 33,000 BTU/hr to boil 5 gallons, my personal experience is to the contrary. I can boil larger volumes than that with about half the BTU rating.

I would wager that your kettle is wide enough to at least partially straddle two burners. Give that a go and keep us posted!

 

[The Pol]

Well, you need approx. 11,000 BTUs, but how you effectively obtain those BTUs will vary.

In most testing, the best a gas burner would give, was around 40% efficiency with its output.

Of course, every burner, every pot and even ambient temperature will cause variation.

This is based on turkey fryers also, and we did this testing here on HBT some 5 years ago. Bottom line, when using gas, the BTU output falls short of the BTU input.

I like the heat stick idea. A single 3500W element will give you 11,000 BTU of utilization. So something half that size would boost your BTU input 5,000 BTUs!

For instance, a single 4500W element is 15,000 BTUs. It will reach a boil from 150F in 9 minutes! With only 15,000 BTUs!

 

[Coolhand78]

I looked at doing that, but don't think I can. If I have the "big" burner on full blast, the kettle will cover less than half of the smaller back burner. Flames going up the side of the kettle seems like a safety concern. Is there something I'm missing on this?

Ironically, my stove seems to be the same (or very similar) to Jake Keeler's in the BrewingTV episode on BIAB. He seems to say that he's limited to a 3 gallon batch in his 8 gallon pot. [ame]https://www.youtube.com/watch?v=o6WVul6IEKk[/ame]

I would wager that your kettle is wide enough to at least partially straddle two burners.

 

[TexasWine]

I looked at doing that, but don't think I can. If I have the "big" burner on full blast, the kettle will cover less than half of the smaller back burner. Flames going up the side of the kettle seems like a safety concern. Is there something I'm missing on this?

Yeah I have the same issue. I just scoot the pot over as far as I can, putting the edge of the flame of the power burner right at the edge of the pot. Even though the small burner isn't completely covered it's still helping a little.

Not sure what safety concerns you might have with not completely covering the burner. There's nothing to melt, and nothing to catch fire. Well, except for your own skin and clothing.

 

[TexasWine]

Well, you need approx. 11,000 BTUs, but how you effectively obtain those BTUs will vary.

In most testing, the best a gas burner would give, was around 40% efficiency with its output.

Of course, every burner, every pot and even ambient temperature will cause variation.

This is based on turkey fryers also, and we did this testing here on HBT some 5 years ago. Bottom line, when using gas, the BTU output falls short of the BTU input.

Oh I totally agree. Burning gas is very inefficient and there are a lot of variables that dictate just what that efficiency is. I just didn't want the OP to loose heart thinking that the numbers were absolute evidence that their system wouldn't work.

My system obviously works even though on paper it probably shouldn't.

 

[The Pol]

Nothing in brewing is absolute

 

[pricelessbrewing]

Half way through a mash.
2 heat sticks + stovetop. Got to strike temp in 15 minutes. 80F to 170F (Overshot strike temp, thermometer was apparently in a cold spot).

 

[purplehaze]

Here you go... https://www.homebrewtalk.com/f11/kettle-shroud-heat-retention-343355/

:rockin:

 

[Yooper]

How about building a heat stick? That is cheap, and fairly easy, and should be able to "boost" your power without spending much money.

 

[Coolhand78]

Thanks everyone for your helpful advice. I have a follow-up question — is it ok to have the lid on the boil kettle while bringing it up to boil, and then remove it to be uncovered (or partially covered) once a boil is reached?

Also one correction — my "power burner" on my stove is 16,000 BTUs (not 12,000). I've seen other posts from people with similar stovetop burners who can boil 6.5 gallons, so I'm not sure what my problem was.

 

[wilserbrewer]

I have a follow-up question — is it ok to have the lid on the boil kettle while bringing it up to boil, and then remove it to be uncovered (or partially covered) once a boil is reached?

Yes it is fine to leave the lid on as you approach boil. Boiling partially covered is not ideal, but likely fine as well, I think you want to achieve approx 10-15% boil off.

 

[TexasWine]

Also one correction — my "power burner" on my stove is 16,000 BTUs (not 12,000). I've seen other posts from people with similar stovetop burners who can boil 6.5 gallons, so I'm not sure what my problem was.

Let us know when you get this figured out. I'd think you could boil 6.5 gallons no problem with a cook top rated at that.

Not that it has an impact, but are you running off natural gas or propane?

 

[Brew_G]

I also have a gas power boil burner - I'm pretty sure it puts out 18000 BTUs. I'm brand new and just bought a 9-gallon pot to do AG BIAB after having done a small boil extract batch a few weeks ago. I currently have a 4-gallon pot, and I can get 3.5 gallons boiling in pretty good time. I have slight concerns about getting 6.5 gallons to a boil, but I'm confident I can get there. If not, I'll just add boiling water here and there to reach my full volume.

 

[Coolhand78]

Ok, thanks! And BTW, I was a person you emailed this morning about shipping my bag out today. Looking forward to doing my first BIAB!

Yes it is fine to leave the lid on as you approach boil. Boiling partially covered is not ideal, but likely fine as well, I think you want to achieve approx 10-15% boil off.

 

[Coolhand78]

It's natural gas. Last night I "boiled" just one gallon in my new 8 gallon aluminum pot, with the lid on and then partially on. I actually used 3 burners for a while, and it only got up to 210. Granted, I only tried for about a half hour, but Im not sure what the deal is. Does wort boil easier than water?

EDIT: I've had no problem boiling 2.5-3 gallons of wort in my 5 gallon stainless steel pot (using just one burner). Could my problem have something to do with the new pot being aluminum in a much larger size?

Let us know when you get this figured out. I'd think you could boil 6.5 gallons no problem with a cook top rated at that.

Not that it has an impact, but are you running off natural gas or propane?

 

[The Pol]

It is acting like a heatsink

 

[TexasWine]

It's natural gas. Last night I "boiled" just one gallon in my new 8 gallon aluminum pot, with the lid on and then partially on. I actually used 3 burners for a while, and it only got up to 210. Granted, I only tried for about a half hour, but Im not sure what the deal is. Does wort boil easier than water?

EDIT: I've had no problem boiling 2.5-3 gallons of wort in my 5 gallon stainless steel pot (using just one burner). Could my problem have something to do with the new pot being aluminum in a much larger size?

Man that is bizarre. I don't understand why it's not boiling. Sure you'll loose more heat because of the larger pot, but not being able to boil one gallon of water seems impossible.

I think I'm out of ideas.

 

[madscientist451]

I have an electric range and shoot for about 4 gallons of wort in the fermenter. I mostly brew in the winter and at night and don't want to be outside brewing.
I have two pots, a 6 gallon and a 3 gallon.
I mash in a 5 gallon cooler and run directly into the brew kettle.
The sparge water is already heated in my smaller pot and I dump that in the cooler, then run the first batch sparge into the kettle, and the kettle goes on the stove with maybe 4.5 gallons of water in it.
My second batch sparge goes into the small pot with about 2 gallons, which I then also put on the stove. I divide my hops by the appropriate amounts, and boil away. After about 30 mins, I've lost some water to evaporation and the small pot is dumped into the large one.
I usually end up with about 4.5 gallons of wort in the pot. I set the pot on the back porch overnight to chill and siphon off 4 gallons of wort to the carboy, leaving behind about 1/2 gallon of trub.
I got the small pot from Walmart for about $12.
I think your specific problem is that your pot geometry is such that its letting go of heat faster than you can add heat.
If the pot was a smaller diameter and taller, perhaps that would help, I don't know if aluminum dissipates heat faster than stainless steel but that could be adding to the problem.
My 6 gallon brew kettle is stainless steel and doesn't look as wide as yours.

 

[purplehaze]

Someone else had a similar issue and was able to figure it out, which is why I posted the link to his thread.

Most of the heat from the burner hits the bottom of the pot and then dissipates. Using the Aluminum flashing retains the heat by forcing it up the sides of the pot. The flashing is very cheap and can be bought at any big box store.

I have modified what he did and use it outside on my propane burners.

A heat stick will work but that would be more expensive and difficult to build than an aluminum skirt.

 

[Coolhand78]

Thanks for this idea. I think I'll try this if it looks like I don't have any other options.

Someone else had a similar issue and was able to figure it out, which is why I posted the link to his thread.

Most of the heat from the burner hits the bottom of the pot and then dissipates. Using the Aluminum flashing retains the heat by forcing it up the sides of the pot. The flashing is very cheap and can be bought at any big box store.

I have modified what he did and use it outside on my propane burners.

A heat stick will work but that would be more expensive and difficult to build than an aluminum skirt.

 

[Devilsnight]

I battled with this for quite awhile. my solution was a new kettle. I had a really nice 4 gal. stainless kettle that I started with. It was really tough to get a rolling boil with 3 gallons of wort. For some reason I decided to buy the el cheapo 5 gallon kettle from my lhbs, it probly weighed half as much (even being bigger in size) My only problem now is worrying about boil over. The difference is night and day. Don't even have to think about putting a lid over it, it gets up and goes.
I searched high and low to find a solution, thought about a stick or propane but that didn't really make sense, hope this helps. It's got something to do with heat transfering through the bottom of the kettle I guess

 

[Brew_G]

It's natural gas. Last night I "boiled" just one gallon in my new 8 gallon aluminum pot, with the lid on and then partially on. I actually used 3 burners for a while, and it only got up to 210. Granted, I only tried for about a half hour, but Im not sure what the deal is. Does wort boil easier than water?

EDIT: I've had no problem boiling 2.5-3 gallons of wort in my 5 gallon stainless steel pot (using just one burner). Could my problem have something to do with the new pot being aluminum in a much larger size?

Any luck?

I have a GE range with a similar setup as yours. For my first brewday with my fairly thin-walled SS 9-gallon pot (this past Saturday), I ended up just using the power boil burner. I did experiment for a few minutes with extending the pot over three burners, but I felt I was losing more heat from the power boil than I was gaining from the other two burners. I got 6.25 gallons of cold tap water up to 163F in 40 minutes, then mashed in. After sparging to get my boil volume (~6.75 gal), my water temp was 151F. I hit the burner and was at a boil 35 minutes later. I had no issues keeping that boil rolling for the remainder.

It's not an ideal situation to have to use a gas range burner for fairly high volumes (though brewing inside on a cold day is nice!), but power burners should do the job.

 

[flars]

"However, 90 minutes later (2 hours total) I could only get the water up to 210, just on the edge of becoming a boil. I even put the lid on (partially), but that barely seemed to help."

At an elevation near 1,000 feet in Sun Prairie, boiling will be less than 212°. Still 90 minutes is a lengthy amount of time.

 

[Coolhand78]

I haven't had time to try a brew yet, but this morning I did post a thread on a SMASH recipe to try for my first biab (thread:First time BIAB, SMASH - Check my recipe before I give it a shot).

I'll report back once I brew. Thanks!