Get your HBT Growlers, Shirts and Membership before the Rush!


Home Brew Forums > Home Brewing Beer > All Grain & Partial Mash Brewing > Measuring pre and post boil volume
Reply
 
LinkBack Thread Tools
Old 06-13-2008, 08:04 PM   #21
FlyingHorse
Formerly Bike N Brew
HBT_LIFETIMESUPPORTER.png
Feedback Score: 0 reviews
 
FlyingHorse's Avatar
Recipes 
 
Join Date: Mar 2007
Location: Evanston IL
Posts: 1,864
Liked 10 Times on 10 Posts

Default

Quote:
Originally Posted by cmgray View Post
If you boild longer than 60 minutes just to get correct gravity, aren't you throwing off your hop additions? i.e. creating higher IBU?
Quote:
Originally Posted by GilaMinumBeer View Post
Maybe, I am not convince yet that an extended boil increases isomerization efficiency. Sure I have read about it, I am just not convince it's that pronounced. I mean, after 60 minutes at 212*F I think I have extracted and isomerized just about everything I can. Not scientific fact but a perceived opinion.
The 60-minute additions wouldn't be a problem...there's very little additional isomerization from 60 to say, 90 minutes.

The problem would be with your flavor and aroma additions. BIG difference between a 10-minute addition and a 40-minute.
__________________
No signature required.
FlyingHorse is offline
 
Reply With Quote Quick reply to this message
Old 06-13-2008, 08:08 PM   #22
Beerthoven
Feedback Score: 0 reviews
 
Beerthoven's Avatar
Recipes 
 
Join Date: May 2007
Location: Cary, NC
Posts: 2,176
Liked 11 Times on 10 Posts
Likes Given: 2

Default

Quote:
Originally Posted by missing link View Post

...

My goal is to get the right volume pre-boil at the right gravity, boil off the right amount and get the correct post gravity at the correct volume.

So if I need 7.5 gallons at 1.042 pre-boil and I boil for an hour, I want to breally close to 6 gallons at 1.052.

A few of my past brews, I have hit my pre-boil gravity and volume, but totally missed my post boil gravity by as much as 10 points and I had more wort than I could fit in the bucket I just don't know how much more.

I'm going to try adding my spritzed with star san IC after the boil is done and measured.

Here is another question. What is more improtant then - is it boiling for exactly 60 minutes and getting the proper hop utilization or is hitting your OG more important?

Linc
Since you are hitting your target pre-boil volume and gravity, all that's left is to figure out your evaporation rate. Once you nail down your evaporation rate you'll be able to hit your target post-boil volume and gravity.

Fill up your kettle with 7 gallons of water and boil it for 60 minutes, just as you would if you were making beer. At the end of the hour measure how much water you have left. Your (hourly) evaporation rate is equal to

[ (pre-boil volume - post-boil volume)/(pre-boil volume) ] X 100

Enter that into BeerSmith, or whatever program you use to help you make recipes. This should be a good approximation to how much you boil off in an hour. Use this figure on your next brew day and if you hit your pre-boil gravity and volume, I bet you will be very close to your post-boil targets too.

Because I know the boil-off rate of my kettle, if I hit my pre-boil volume and gravity I know that I'll hit my target post-boil vol and grav before I even begin the boil.
__________________

Primary/Secondary: --
Kegged: #114 Oatmeal Stout, #115 American Amber
Planned: APA, IPA, Nut Brown

Beerthoven is online now
 
Reply With Quote Quick reply to this message
Old 06-13-2008, 08:26 PM   #23
GilaMinumBeer
In yo' garage, steelin' yo parts.
HBT_LIFETIMESUPPORTER.png
Feedback Score: 0 reviews
 
GilaMinumBeer's Avatar
Recipes 
 
Join Date: Jan 2008
Location: Oblivion
Posts: 48,868
Liked 4956 Times on 4522 Posts
Likes Given: 60

Default

Quote:
Originally Posted by Bike N Brew View Post
The 60-minute additions wouldn't be a problem...there's very little additional isomerization from 60 to say, 90 minutes.

The problem would be with your flavor and aroma additions. BIG difference between a 10-minute addition and a 40-minute.
Good catch. I was reffering strictly to bittering additions.
__________________
GilaMinumBeer is offline
 
Reply With Quote Quick reply to this message
Old 06-14-2008, 02:43 PM   #24
FlyGuy
Feedback Score: 0 reviews
 
FlyGuy's Avatar
Recipes 
 
Join Date: Jan 2007
Location: Calgary, Alberta
Posts: 3,618
Liked 136 Times on 42 Posts
Likes Given: 7

Default

Quote:
Originally Posted by missing link View Post
My only other question then is how do you guys handle the displacement of the chiller?
If you are REALLY concerned about measuring post-boil volume accurately, then simply chill to about mash temp, remove the chiller (it is cool enough to handle now), and take your volume reading. That way the pre- and post- volumes are measured at the same temp.

Regarding gravity, hop utilization, and boiling times, I always make sure that my pre-boil volume and gravity is at target levels (can adjust with water and/or DME if it is really off), then boil for a fixed length of time, pre-determined for the recipe. The hop utilization is calculated for that boil time in the recipe, so it always stays fixed. As long as you know your evaporation rate (or close to it), your post-boil volume becomes a predictable consequence of your process (i.e. one should not change the boil process to reach a particular volume on-the-fly because it could throw your gravity and bitterness out).
FlyGuy is offline
 
Reply With Quote Quick reply to this message
Old 06-14-2008, 05:21 PM   #25
korndog
Feedback Score: 0 reviews
 
korndog's Avatar
Recipes 
 
Join Date: Nov 2007
Location: westlake village, ca
Posts: 1,123
Liked 7 Times on 5 Posts

Default

Quote:
Originally Posted by ajf View Post
To see how much the IC displaces the water in the kettle, fill the kettle with 5g cold water, add the immersion chiller, and then re-measure.
I always start the boil with 6.75g water, and boil for 75 minutes. I end up (after evaporation, hop absorption, dead space etc.) with 5.25g give or take a pint.
I have promash set up with an evaporation rate of 15g/hour. Just goes to show how much I use the water usage calculators.
-a.
Yep. Dual calibration for the old stick.

I have had wild swings in my boil off rate in the past and ended up missing big too. I usually do 90 minute boils with the first hops at 60. If they are at 60 minutes, it's easy enough to check my boil-off rate prior to the first hop addition and adjust if I am off. If FH are at 90 minutes, then I'm stuck with a little extra time for that addition if my evap. rate is low. The hop isomerization rate drops off big at like 30 minutes, so the extra bittering would be minimal in either case but less so for the 90 minute first hops.

KD
__________________

"..can the human soul be glimpsed through a microscope? Maybe, but you'd definitely need one of those very good ones with two eyepieces."


Twitter: LarryKonis

korndog is offline
 
Reply With Quote Quick reply to this message
Reply



Quick Reply
Message:
Options
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Looking for advice - measuring brew kettle volume zbonaker All Grain & Partial Mash Brewing 26 03-05-2014 01:44 PM
Measuring Oats by volume Johnny9 General Techniques 1 03-27-2009 02:21 PM
Low Post Boil Volume gpogo All Grain & Partial Mash Brewing 5 10-14-2008 05:30 PM
Measuring Hops by volume not weight. RC0032 Recipes/Ingredients 6 09-30-2008 04:48 PM
Measuring volume in boil kettle... greg75 Equipment/Sanitation 18 01-28-2007 04:29 PM



Newest Threads

LATEST SPONSOR DEALS