[tomsawyer]

You went from 7.5gal to 5gal in 1.5hr.  That is quite a bit but with a hard boil and a lot of surface area I would imagine its possible.  Or it could be an indication that you didn't have 7.5gal to begin with. ;P

Tubercle I thought about that, the readings would be off by the same value and the math wouldn't work out either.

[Will's Swill]

I'm with the Weaz, I boil in a dry climate and it wouldn't be terribly unusual for me to lose 2.5 gallons in 90 minutes.  Especially for big beers where I'm trying to lose volume.

[bluesman]

Boiling 2.5 gal or 33% of the wort off in 90 min is really not necessary, unless of course that's your ultimate goal. I think we all can agree it's possible to boil off at that rate, as it looks like it really happened, assuming his volumes are accurate. Evaporation rates can vary frm the desert to the swamps but can also be somewhat controlled by the energy applied.

A hydrometer should be calibrated using distilled or RO water at the original calibration temp which should be marked somewhere on the hydrometer scale.

I recommend taking accurate water/wort volume measurements into the mash tun and kettle. This will help you better understand your efficiency and also help target your pre and post boil gravity. In addition, I also recommend monitoring your boiloff rate in order to accurately target your volume post boil.

BTW...did you measure your mash pH?

[cheba420]

Boiling 2.5 gal or 33% of the wort off in 90 min is really not necessary, unless of course that's your ultimate goal. I think we all can agree it's possible to boil off at that rate, as it looks like it really happened, assuming his volumes are accurate. Evaporation rates can vary frm the desert to the swamps but can also be somewhat controlled by the energy applied.

A hydrometer should be calibrated using distilled or RO water at the original calibration temp which should be marked somewhere on the hydrometer scale.

I recommend taking accurate water/wort volume measurements into the mash tun and kettle. This will help you better understand your efficiency and also help target your pre and post boil gravity. In addition, I also recommend monitoring your boiloff rate in order to accurately target your volume post boil.

BTW...did you measure your mash pH?

Ron,
No sir, I was not trying to boil off that much. I was trying to boil off about 1.5 G and figured I'd boil off about a gallon per hour. My boil was low and controlled. Would it be helpful to keep track of my boiling temp and keep it as close to 212 as I can. I would assume that if I have it up at 225* I'm going to boil off a lot more than I would at 225*
I'll calibrate my hydrometer tonight and see where that gets me. I always measure water into the tun and wort into the kettle accurately. Somehow, my calcs were off by 2 qts of sparge water. Noted. Wont be doing that again. (hopefully). I've been using 5.2 in my mash recently...so the PH should have been pretty dialed in but no, I didnt actually check it.

[tubercle]

Would it be helpful to keep track of my boiling temp and keep it as close to 212 as I can. I would assume that if I have it up at 225* I'm going to boil off a lot more ....

 You can't get the temp above 212* under the perssure of 1 atmosphere. It doesn't matter if you are using a turkey frier burner or a Pratt & Whitney. Ain't gonna happen. You can increase the intensity of the boil but not the temp.

[bluesman]

Considering that you live in Mesa, Arizona your evaporation rate will be higher than normal but if you keep the boil to a steady "rolling over" type action that should be plenty. As long as you are constantly exposing new surface (turning over) area of the wort during the boil you will be volatilizing the pre-cursers to DMS, encouraging maillard reactions, as well as generating melanoidins during the boil. This action will suffice, and you will also minimize the evaporation rate as well.

[bluesman]

Would it be helpful to keep track of my boiling temp and keep it as close to 212 as I can. I would assume that if I have it up at 225* I'm going to boil off a lot more ....

 You can't get the temp above 212* under the perssure of 1 atmosphere. It doesn't matter if you are using a turkey frier burner or a Pratt & Whitney. Ain't gonna happen. You can increase the intensity of the boil but not the temp.

+1

[morticaixavier]

you could get the temp a little over 212 with a strong sugar syrup. I don't know exactly how much above 212, not much I would guess but some

[Tristan]

What temperature was the wort when you measured pre-boil volume?  For a long time I didn't realize what a difference this makes.  For example volume measures 5% higher at boiling than at room temperature. 

I always assume I'll have my burner going as soon as bottom of the boil vessel is covered with wort.  I know Beer Smith has a setting for "cooling lost percentage" under "Equipment."  I usually put this at 4-5% because I assume the wort will be quite hot when I measure volume (in the upper 100s/lower 200s).  I think this is 4% by default.

If you measured 7.5 gallons at high temperatures it would be less going into the fermentor in addition to how much you boiled off.  If measured near boiling it would actually be 7.125 gallons at room temperature. 

In your example, you still would have had to had a 20% boil off rate and measured your pre-boil at near boiling to get that kind of loss.

[cheba420]

What temperature was the wort when you measured pre-boil volume?  For a long time I didn't realize what a difference this makes.  For example volume measures 5% higher at boiling than at room temperature. 

I always assume I'll have my burner going as soon as bottom of the boil vessel is covered with wort.  I know Beer Smith has a setting for "cooling lost percentage" under "Equipment."  I usually put this at 4-5% because I assume the wort will be quite hot when I measure volume (in the upper 100s/lower 200s).  I think this is 4% by default.

If you measured 7.5 gallons at high temperatures it would be less going into the fermentor in addition to how much you boiled off.  If measured near boiling it would actually be 7.125 gallons at room temperature. 

In your example, you still would have had to had a 20% boil off rate and measured your pre-boil at near boiling to get that kind of loss.

Tristan, I pulled all of my wort into the kettle before I put the flame to it. So, the wort was measured at mash temps, slightly cooler do to the time involved and the gradual cool down. 140's - 150's or so....

[morticaixavier]

Seems like the boiloff amount is reasonable, if a little high but explainable by low humidity, surface area. The big question here is still the disapearing sugar. as tomsawyer pointed out, the post boil gravity should have been much higher. Unless there was ALOT more wort left in the hops/break material in the kettle post boil. if there was 1.25 gallons left at the bottom of the kettle instead of the stated .25 that would work out just about right. 430 points / 6 is 1.071

**EDIT** combine that with the volume increase/decrease caused by temp differncial and you get closer to that 1.5 gallons per hour number as well.

[cheba420]

Man....This forum truly is awesome. You guys are all so resourceful and you need to know how much your insight is appreciated. I will be paying very close attention to my boil off moving forward and will ultimately shoot for more wort in the kettle pre boil so I can wind up with my desired 6 G to the fermenter.

Morticaixavier- As for the break material left in the kettle, I dumped it out into a measuring picture to make sure. It was 1 qt, exactly.

I have not calibrated my hydrometer yet. Didnt have any distilled water @ home last night. I'll test it tonight. I can see how the little slip of paper inside with the scale on it could slip down the inside tube of the hydrometer and effect accuracy. What a pain in the ass. I would have thought that tool was on point all the time, no questions. Been at this for a while now and still learn new stuff all the time. I'm pretty sure if I adjust my pre boil volume to compensate for my boil off and I dial my hydrometer in....I should be in business! Whats the word on refractometers? I've bought a few hydrometers over the last five years. I think if I have to spend any more money to measure sugar, I may as well make the jump to the refractometer and stop wasting time and money on the hydrometers. Are they more accurate? Durable? Thoughts?

[tomsawyer]

A refractometer is a fine tool for measuring OG, its a pain in the a$$ to use for FG and not that accurate.  I have the refrac because I make wine and I do love it for the initial measurements.

[tubercle]

 Don't invest in distilled water just yet. Tap water at room temperture will give you a good indication if you need to research further. If it is way off with tap water it will be way off with distilled water. If it real close. within a couple of 00,s, then you might want to get distilled water and test at the exact calibration temp.

  If it is off a good bit then trash it; they're cheap and not worth doing all the calculating.

 Tip of the day: If you just have one, you will break it soon. Buy 2 and it will last forever.

[Hokerer]

Tip of the day: If you just have one, you will break it soon. Buy 2 and it will last forever.

+1  And applies to way more than just hydrometers