Science Q: how much water at 40 degrees would you add to boiling wort to hit a temp

[powwowwow]

Hi Everybody,
I want to do a partial cool post boil, in order to steep post boil additions at 170 to 180 degrees. So I'm thinking of brewing a few barrels short, then adding cold water after the boil until I hit my target temp. Then I'll let it pasteurize and steep at that temperature basically, before sending it through the plate chiller on the way to the fermenter.

But the question is, how much water do I have to add to hit my target temperature?

Is there a formula for how much water at temperature x to add to boiling wort in order to reach temperature y?

Thanks for your help,
Joe

[Scott M]

Geez, Joe....I got a D in Fluid Dynamics!!

Got anything easier...

I would give yourself at least 1/3 of your capacity to add the 40 degree water to, and; I would experiment with a kettle of water before risking product.

[beejay]

Not an expert at this, but a google search provided some useful links.

http://www.engineeringtoolbox.com/mixing-fluids-temperature-mass-d_1785.html

http://www.onlineconversion.com/mixing_water.htm

Assuming the wort is at ~212F I think you need to add roughly 25% of the original volume in 40F water to bring it down to 170-180F

So if you had 200 gallons of boiling wort and added 50 gallons of 40F water you should get to your target range.

[CPESystems]

To keep it simple assume your wort has a specific heat of 1 which is the same as water and a 250 gallon batch.

200 gallons X (212-177.5) x 8.34 = 57546 BTUs
50 gallons X (177.5-40) x 8.34 = 57337 BTUs



If you start with 200 gallons of wort at 212 and add 50 gallons at 40 F you will end up about 177.5 F.

Now, I believe wort has a specific heat of about 1.05 (brewers please correct me if I am wrong) so actually the final temperature will be closer to 179 F.
The ratio is 80% wort to 20% water.

If you want to get to the cooler end of your range try 185 gallons of wort and 65 gallons of water for a final temperature of 169 F
The ratio is 74% wort to 26% water.

A ratio of 75 to 25 will give you a final temp of 170.5 F.

[Larry Doyle]

QUESTION #2: If a beer truck leaves Chicago going 60 mph and another beer truck leaves Topeka going 72 mph where will they meet and does anyone really care?

[Scott M]

Only those who are lucky enough to be at the point of impact. ;-)

[CPESystems]

With a growler in hand.

[powwowwow]

thanks guys

winning thread on all fronts, number one first place, thanks all!

[sleeper]

pre-cool

adding water post boil seems to me a horrendous idea.

especially if this water contains chlorine.

lets not forget about adjusting all your IBU and OG math.

I run through the HX as i'm xfering to the WP and drop down to 180F ish to minimize SMS -> DMS formation and to steep.

If one was to insist on adding water, the math you want is a blending formula. Aa + Bb = Cc

Aa = Temp and weight of wort
Bb = temp and weight of water added
Cc = total temp and weight

some algebra will give you a volume by weight depending on the temp of the water in.

suppose x = b, c can be described as (a + x)

i think.

SKOL!

levi

[Jephro]

boil-off to the beer gods

As far as Chlorine goes i never found it to be a problem but i was only adding 5-10% of post boil volume. I added using City H2O line (via Particulate/Carbon cartridge Filters) while WP was running ASAP after flame out and in my experience the cl would gas off before KO.

I never aimed to add water post-boil and would not suggest it to be a SOP, for a host of reasons i wont waste electrons on. That said, in the rare instance of over boil(off) with higher than expected gravity it was a great tool for me- being very experienced on system (500+ brews on it) i didn't have to calculate anything, as long as i just did it w/o thinking. I was usually spot on as far as FV grav went. .....and NEVER, EVER, EVER did it to IPA :-)

[powwowwow]

bad idea?

For those who think this would be a horrendous idea, I would like to know why. I'm assuming that if I'm holding the wort at 180 for a half hour plus, any chlorine would gas off. These temperatures are well above pasteurization range, so there shouldn't be any microbial risks. Possibly the higher gravity boil could have an adverse impact on head retention? What's the piece of the puzzle I'm missing?

p.s. this is for pasteurizing honey without boiling off the aromatics... not for hops

[roc-craven]

Added water

I have a brewday timer I wrote for myself when I was home brewing. For the last 3 years of pro brewing it has grown to have some extra features I needed in the brewery. One of them being temperature of mixed fluids.

It may help. You can get it here. www.beerbelliesbrew.com It's free.

[Mike Elliott]

K.i.s.s.

For those who think this would be a horrendous idea, I would like to know why. I'm assuming that if I'm holding the wort at 180 for a half hour plus, any chlorine would gas off. These temperatures are well above pasteurization range, so there shouldn't be any microbial risks. Possibly the higher gravity boil could have an adverse impact on head retention? What's the piece of the puzzle I'm missing?

p.s. this is for pasteurizing honey without boiling off the aromatics... not for hops

I would hate to leave wort hot like that for so long because of the DMS concerns and loss of hop aromatics. I wouldn't mix city water because instead of gassing off, the chlorine will instantly halogenate all those nice phenols and you'll get terrible off-flavors. Why not just dose the honey in line when headed to the HX during knockout? Lacto and pedio D-values at 210F are vanishingly small, so even a few seconds of contact time is plenty for a multi-log reduction in CFUs. No infection, no loss of volatiles in a closed pipe, no complicated mixing, no chlorine, no huge time wasting at the end of the day. Easy peasy, lemon squeezy.

[OneMoreBrewer]

For those who think this would be a horrendous idea, I would like to know why. I'm assuming that if I'm holding the wort at 180 for a half hour plus, any chlorine would gas off. These temperatures are well above pasteurization range, so there shouldn't be any microbial risks. Possibly the higher gravity boil could have an adverse impact on head retention? What's the piece of the puzzle I'm missing?

p.s. this is for pasteurizing honey without boiling off the aromatics... not for hops

I was under the impression that we boil for and extended period of time to also help lower the pH of the wort. Wouldn't adding 25% more water at a higher pH (say 6.5) have an effect? I have no idea of the pH of our wort post boil right now, but I might check tomorrow. The pH is directly related to the microbiological risk as well, correct? I know these factors may not be a practical issue, however in principal.

Does honey need to be pasturized? I was under the impression it is a low pH?