Measuring pre and post boil volume

I've done a few AG batches and my system is pretty sound. I am having trouble with on area though and I wanted to understand what you guys do.

I sparge into a graduated bucket to measure my pre-boil volume and I also have a somewhat calibrated stick that I can insert into the boil kettle to measure volume.

Once I hit my pre-boil volume, I stop sparging and start boiling. I know that I need to boil off a certain amount. My problem is that at 45 minutes, I stick my immersion chiller into the boil and it raises the liquid level. At 60 minutes I shut off the flame but I am unable to measure my post boil volume.

When I rack off into the carboy's, I am getting more wort than I expected. I have my evaporation rate in beer smith set to 12%.

Here is my questions

1. How do you measure pre and post boil volume
2. what evaporation rate do you use to calculate boil off?

Linc

Why can't you lift the chiller for a few seconds and take a level reading with your stick?

I suppose I could get a glove and do that. After 15 minutes in boiling wort, the copper is to hot to touch.

Linc

Even an oven mitt would work I would assume

Or you could sanitize the IC in starsan or whatever and put it in at the end of the boil.......it doesn't HAVE to go in at 15min.....

But, ultimatly the source of your problem seems like calculations....play around with your brewing software a bit more and when you brew next try and write down all of the numbers....like what all your water amounts and gravity

1. How do you measure pre and post boil volume
Preboil: Same as you I think...I have one of those buckets with measurements on the side, so I take one measurement of the first runnings, then add the batch sparge runnings.

Post-boil: I have marked the inside of my boil kettle at 5 and 6 gallons, using a nail to scratch it into the aluminum. I'm sure you could find a better solution, but this works for me. If I'm WAY under, I'll sparge a bit more. If I'm WAY over, I keep boiling until I hit the 6 gallon mark. Most of the time, I end up right around 5.5 gallons. The real measurement comes when I transfer to the primary...I've got that marked so I can tell exactly how much post-boil volumne I have.

2. what evaporation rate do you use to calculate boil off?
My evaporation during the spring was 9%, but my last batch was closer to 11% due to hotter/dryer weather. I assume this will continue to rise, as we get very hot, dry summer weather around here. Since I use a 7.5 gallon turkey fryer pot, I usually have too much wort to put it all in at the beginning. I'll keep the extra in a pot during the brewing process, and if my evaporation is really high I'll add some wort to the pot.

I know my methods are pretty un-scientific, but I find that measurements of water...both in the mash and in the boil, are hard to pinpoint. There are just too many variables; grain types, grain amount, mash step length, humidity, ambient temperature, etc.

Yeah, lately for 5gal batches w/10lb of grain I've been mashing w/3gal and sparging w/6gal. 6gal is really too much but it's good bc I just keep running off until I have how much wort I want in my pot and the rest stays in the MLT. It makes it easier to dumb out the spent grain bc there is about a gallon or so of water in there to swish around.

For preboil I go up to ~6.5 gal if I'm boiling for 60min or 7gal for 90min. 7gal is right at the studs for my kettles handles....6.5 is about a half inch or so below...yeah I know really accurate

I ferment in a graduated bucket. I use the same bucket to measure the pre-boil volume. Hence, I always have consistent pre- and post-boil volume measurements. After that its just a matter of calibrating BeerSmith with the correct evaporation rate. Mine is set at 20%. I hit my target pre- and post-boil volumes almost exactly every single time.

My only other question then is how do you guys handle the displacement of the chiller? Or are you using a plate chiller or counterflow where there is no affect on your volume readings?

Maybe I'm over complicating things. Next brew I'm going to put the chiller in a hot star san solution and just let it sit until I am done boiling or try lifting it out of the boil pot.

The boil is my only variable that I haven't nailed down. I am getting pretty consistent efficiency out of my electric RIMS system and I have a new burner that can boil 10 gallons much better.

Thanks for the feedback

Linc

I tend to not be concerned about the volume. There are just too many variables to deal with to nail it everytime. Sure I anticipate evaporation (1G/H Summer, 1.5-2G/Hr Winter) but never check it prior to going into the fermenter.

Instead, I monitor gravity with my refractometer and I boil until I either hit a 60 minute minimum or I keep going til I get to my target gravity.

On the rare occasion I find that my fermenter is low in volume, well then I decide if I want to dilute and lower my gravity. On the typical brewday I am a gallon or 2 over my final volume and that wort gets canned for starters (most likely) or chucked into a jug and fermented with an experimental yeast, late addition (fruit, sugar, etc...), or a wild fermentation temp (rocket fuel).

The latter I find to be the most fulfilling as it afford some playfullness without the potential of sacrificing a full 5 gallons. If I like the end result then I can tweak it a bit and go full volume.

missing link said:

My only other question then is how do you guys handle the displacement of the chiller? Or are you using a plate chiller or counterflow where there is no affect on your volume readings?

Maybe I'm over complicating things. Next brew I'm going to put the chiller in a hot star san solution and just let it sit until I am done boiling or try lifting it out of the boil pot.

The boil is my only variable that I haven't nailed down. I am getting pretty consistent efficiency out of my electric RIMS system and I have a new burner that can boil 10 gallons much better.

Thanks for the feedback

Linc

Click to expand...

Yes, you might be overcomplicating things a little bit...

I sanitize my immersion chiller with starsan a minute or two before I need to use it. There is no need to heat your starsan solution or let your chiller sit in starsan for a long time [thread=68731](see this thread)[/thread]. Starsan works with a 2 minute contact time, that's all you need.

missing link said:

My only other question then is how do you guys handle the displacement of the chiller? Or are you using a plate chiller or counterflow where there is no affect on your volume readings?

Maybe I'm over complicating things. Next brew I'm going to put the chiller in a hot star san solution and just let it sit until I am done boiling or try lifting it out of the boil pot.

The boil is my only variable that I haven't nailed down. I am getting pretty consistent efficiency out of my electric RIMS system and I have a new burner that can boil 10 gallons much better.

Thanks for the feedback

Linc

Click to expand...

Try this instead. Fill your kettle with 2 gallons of water and boil it full tilt for an hour. Measure whats left. Sure the sugars will effect boil of to some degree but, on the other hand, humidity will have a more profound effect.

There you have it. You can real world test the boil off and no chillers have to be involved.

Easy Peasy.

I don't measure post-boil until it's in the fermenter. I'm not going to change how long I boil based on the volume that's remaining, b/c that would mess up the hop schedule. I fthe volume is too high, not much I can do. If it's too low, I can top up in the fermenter (or not) just as easily as in the kettle.

It helps that my boil-off is pretty predictable and repeatable at 1 gal/hr, but I'm not sure what I'd do if I had a post-boil measurement that was "off" in the kettle anyway.

Even if you want to sanitize you IC in the chiller, you do not have to boil it for 15 minutes. That's overkill upon overkill. If you dropped it in right after cutting the fire and give it a few moments or a minute, that's good enough. The bugs you are worried about aren't that tough.

And, I just use a calibrated plastic spoon for my volume measurements. My boiloff is right around 1.5 gallons/hr.


TL

I just measure my volume with my mash rake that I have premarked right before I put the IC in the kettle, 10 min. of boil will be of little significance at this stage, I end up almost dead on in the fermenter, hope this helps

Bike N Brew said:

I don't measure post-boil until it's in the fermenter. I'm not going to change how long I boil based on the volume that's remaining, b/c that would mess up the hop schedule. I fthe volume is too high, not much I can do. If it's too low, I can top up in the fermenter (or not) just as easily as in the kettle.

It helps that my boil-off is pretty predictable and repeatable at 1 gal/hr, but I'm not sure what I'd do if I had a post-boil measurement that was "off" in the kettle anyway.

Click to expand...

In this case, you miss out on correcting some variables. How do you know how much is left in the boil pot?

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

GilaMinumBeer said:

Instead, I monitor gravity with my refractometer and I boil until I either hit a 60 minute minimum or I keep going til I get to my target gravity.

Click to expand...

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?

missing link said:

In this case, you miss out on correcting some variables.

Click to expand...

I measure gravity and volume preboil. There's no variable I can correct in the kettle at the end of the boil that can't be corrected either preboil, or in the fermenter.

How do you know how much is left in the boil pot?

Click to expand...

I know what I started with, and my boil-off is very predictable. Even if it weren't, I don't care. Again, if it's too little, I can top up in the fermenter. If it's too much, there's nothing I can do...more boiling kills the hop schedule.

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.

Click to expand...

Mine too.

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.

Click to expand...

Not sure how this is possible, at least based on the example you gave above. You're starting with 7.5 gallons at 1.042, shooting for 1.052, and ending up around 1.042 (10 points off)?

I just don't know how much more.

Click to expand...

To me, this is the core of your problem. If you don't know how much you have post-boil, then you don't know you're boiloff rate and you can't adjust for future batches.

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

Click to expand...

If you're ending up with too much wort to fit in your fermenter, then whether or not you're measuring with/without the IC is irrelevant. You're not boiling long enough.

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?

Click to expand...

Both. It's knowing how long you need to boil to hit your target OG and fermenter volume, and using a hop schedule that fits that boil time and your desired IBUs/flavor/aroma additions. All my hop schedules start at 60 min, but my boil time may need to be longer than that to get the right volume/OG. The extra boiling has to take place before the hops are added..which means you need to be able to accurately predict the length of your boil...which means you need to know your boiloff rate.

cmgray said:

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?

Click to expand...

Never tested it and have yet to taste a problem with it.

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.

On the flip side of this equation tho', if I bittered for say 1.080 OG and my mash result was say 1.070 then I'd expect that if I didn't concentrate the sugars I would be too bitter to begin with and the act of concentrating the sugar would further balance the wort, would'nt you say? as to when I actually add the hops for bittering, meh.

Kinda like FWH. Tests show that the method has a 10% (or somethinh like that) increase in extraction efficiency but taste panels describe a smoother bitterness but no perceived increase in bittering.

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.

cmgray said:

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?

Click to expand...

GilaMinumBeer said:

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.

Click to expand...

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.

missing link said:

...

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

Click to expand...

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.

Bike N Brew said:

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.

Click to expand...

Good catch. I was reffering strictly to bittering additions.

missing link said:

My only other question then is how do you guys handle the displacement of the chiller?

Click to expand...

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).

ajf said:

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.

Click to expand...

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