How many BTUs to boil 14 galons of wort

[jakee117]

I have decided to start doing bigger batches. I have a huge brew pot that should be able to accomodate 18 gallons. I would like to do a 14 gal batch of EdWorts kolsch.

1) Will I have sufficient BTUs using the standard Turkey fryer ( 55k BTU ) to boil? I could do a dry run with just water to see but I would appreciate it if anyone could share if they have used this set up for a bigger batch.

2) For this bigger batch my LHBS only had 1 smak pak Wyeast Kolsch. Is a starter mandaroty? Note : I will be breaking this down into two primary fermenters.

 

[Yuri_Rage]

I don't think I'd use a 55k BTU burner for that big a batch. Certainly do a test with water before committing to a brew.

I use a 300k burner (natural gas) to boil 17.5 gallons, and it works wonderfully. I wouldn't want to go too much smaller.

 

[RedSun]

That WYeast is good for 5 gallons so I'd go with a big starter for that much wort. You're fermenting nearly 3x as much wort as recommended for the pack, after all.

 

[z987k]

while 55k might get the job done, man oh man will you be standing there awhile.

 

[david_42]

1. You'll need a starter.
2. I've never seen anyone do 14-15 gallon batches with under 100,000 BTU (more often 200K), so a dry run is a very good idea.

 

[Orfy]

I'm too tired and druk plus I can't be arsed.

http://online.unitconverterpro.com/unit-conversion/convert-alpha/heat-capacity.html

1 kilojoule = the amount of work converted to heat that will raise the temperature of 1 pound of water 1°F is 778 foot-pounds; in metric units, 1 calorie, which raises 1 gram of water 1°C, equals 4.184 × 107 dyne-centimeters, which equals 4.184 joules.

1 kilojoule = 0.94781712 btu

Any one have an answer? = 0.94781712 btu

Any one have an answer?

 

[Scotty_g]

You can use as small a burner as you want as long as you 1) limit heat losses to the atmosphere (including steam) and 2) are patient. There is only so much you can do about #1 (unless you design some crazy-efficient burner), so your choices are waiting vs burner cost. You won't use appreciably more fuel to boil with a bigger burner, all other things equal.

It takes 1 btu/lb to raise water (or as a first approximation, relatively low-concentration wort) 1 F. Water weighs 8.3 lb/gal. So to bring your 14 gallons of water from 70 F to 212 F (close to the boiling point--this depends on dissolved solids) would be 14 x 8.3 x (212 - 70) = 16500 btu's. If you get all of the heat into the water (which you don't!) it will take a 55kbtu/hr burner a mere 0.3 hours (18 minutes).

Since the efficiency of the burner for getting heat into the water is probably < 50% (33%?), *and* the pot loses heat to the room, it's going to take three times that long (or worse). Keeping the lid on to minimize evaporation will help, if you want that.

Once the water/wort is boiling, the heat of vaporization is 1000 btu/lb (nominally). I can't tell you how much boiling is required to keep the water moving, but you can estimate how fast you will boil off the water from the burner size. The example burner of 55kbtu/hr @ 33% would boil 18 lb/hr (2.2 gallons) at full firing.

As I'm a card-carrying member of the International Association of Pedants, I will point out some flaws in this argument before someone else does:
1) wort will boil at a higher temperature because of dissolved solids, increasing heating needs
2) the heat of vaporization will increase as the wort boils (one reason that it's harder to evaporate the last lb of water than the first)
3) altitude and barometric pressure will matter

My response to these points is RDWHAHB. Assuming beer behaves like water is close enough.

Hm, now that I think about it, I should figure out how much beer I could make with the 350 million btu/hr boiler at work...

Edit: I find it ironic that an American answers an Englishman's question about *British* thermal units (no offense intended, of course).

 

[malkore]

I'd suggest getting a KAB5 burner for a brew kettle that large. 125,000 btus should do it.

 

[jakee117]

You can use as small a burner as you want as long as you 1) limit heat losses to the atmosphere (including steam) and 2) are patient. There is only so much you can do about #1 (unless you design some crazy-efficient burner), so your choices are waiting vs burner cost. You won't use appreciably more fuel to boil with a bigger burner, all other things equal.

It takes 1 btu/lb to raise water (or as a first approximation, relatively low-concentration wort) 1 F. Water weighs 8.3 lb/gal. So to bring your 14 gallons of water from 70 F to 212 F (close to the boiling point--this depends on dissolved solids) would be 14 x 8.3 x (212 - 70) = 16500 btu's. If you get all of the heat into the water (which you don't!) it will take a 55kbtu/hr burner a mere 0.3 hours (18 minutes).

Since the efficiency of the burner for getting heat into the water is probably < 50% (33%?), *and* the pot loses heat to the room, it's going to take three times that long (or worse). Keeping the lid on to minimize evaporation will help, if you want that.

Once the water/wort is boiling, the heat of vaporization is 1000 btu/lb (nominally). I can't tell you how much boiling is required to keep the water moving, but you can estimate how fast you will boil off the water from the burner size. The example burner of 55kbtu/hr @ 33% would boil 18 lb/hr (2.2 gallons) at full firing.

As I'm a card-carrying member of the International Association of Pedants, I will point out some flaws in this argument before someone else does:
1) wort will boil at a higher temperature because of dissolved solids, increasing heating needs
2) the heat of vaporization will increase as the wort boils (one reason that it's harder to evaporate the last lb of water than the first)
3) altitude and barometric pressure will matter

My response to these points is RDWHAHB. Assuming beer behaves like water is close enough.

Hm, now that I think about it, I should figure out how much beer I could make with the 350 million btu/hr boiler at work...

Edit: I find it ironic that an American answers an Englishman's question about *British* thermal units (no offense intended, of course).

Thanks everyone. I of couse will try a dry run... or in this case a wet one. I came up with a similar figure of about 16k BTUs at 100% efficiency. I might put a aluminum foil shroud arond the circumference of the burner to see if this can be done. Im not really worried about the time it takes to et it up to the boil, however keeping it there and removing the lid to help drive off DMS has me concerned.

I also assume that wort will boil under 212 due to the dissolved solids. If the dry run dosent work its time for a burner upgrade.

I will try this within the next few weeks and post results ... maybe with a Temp vs Time graph?

 

[Lil' Sparky]

I've got a standard turkey fryer w/ 10 psi regulator. It works fine for 11 gal batches (~ 13.5 gal pre-boil). My average brew day takes < 4hrs from dragging equip out to having everything put away. I don't think it's really adding much time to my brew day.

 

[Scotty_g]

Dissolved solids will raise the boiling point of water. IIRC it's about 0.5 °C for each mol/L of nonionic solutes (sugar) and twice that for ionic solutes (salt). 6 lb of malt, assuming it's C6H12O6 (which it's not), in 5 gallons of water would cause a boiling point rise of about 0.7 °F. Your thermometer will probably not be able to measure that.

That said, our brew kettle hits boil about 208 F. We're only ~650 ft above sea level, which should cause a negligible drop in boiling point. I think our thermometer is off

 

[jakee117]

Thanks for all of the great advise and comments. I did my full big batch boil test. the results are tabulated below:

Time Temp ( F )

0 min 58

15 min 111

30 Min 156

45 Min 186

60 min full boil


Note this was covered ( lets face it I will be getting a new burner ). I uncovered it to simulate a a real boil at this point ( drive off DMS etc ). Had no problem holding this with ambient tem about 32F. I am not thrilled with the level of "bumping" of the boil. What I mean by this is you get localized blow offs of boiling watre. My brew pot is WIDE , I think I may need some boiling stones.

I guess this is an odd topic. When I worked in the Lab ( I am a Chemist in a former life ) and I had this type of boil I would use boiling stones ( I think they were pumice ) to the solvent. This produced a nice even streaming boil. What do you think about doing this in a brew batch? I could wash up some never been used pumince from my grill and use this for the boiling stones.

Just thinking out loud I used the boiling stones in the lab to stop... guess what boilovers. I wonder is this would be a simple cure for boilovers. With my set up it would be a perfect experiment as I dont have too much room at the top of my pot with 14 gallons.

anyone?

 

[Scotty_g]

An hour to get to boil? Yeah, a bigger burner would be in order.

I'm sure boiling stones would help promote boiling, but keeping them clean will be tough if they're porous. I don't know if AG brewing is different from extract brewing as far as hot break, but when we put the DME in our extract brews there is about a 5-minute period where that's some foamy stuff. I don't think boiling stones would fix that.

I wouldn't worry with the stones, just make sure you're extra-careful when it first gets to a boil. Keep the second homebrew in the fridge until that's done