questions on hitting post boil volume

I've recently switched to a larger boil kettle and haven't quite tuned in hitting a perfect final volume of 5.5 gallons.

My questions is how do you all do this? I see there being two choices.

A) I could do a test boil for an hour with 6 gallons and then measure exactly how much boiled off and then increase my boil time if I need to end up with less wort or add more water if necessary.

or...

B) Limit how much wort I extract during mashing/sparging.


I see problems with choice B in not hitting planned OG's.

Do you always mash and sparge with a fixed amount of water per pound of grain or vary it per recipe?

I usually mash with 1.25 or 1.5 qts/lb depending on the types of grain and batch sparge with 1.5 qts/lb. My original problem was coming up with less than 5.5 gallons and lately I've had extra wort given I've just had larger grain bills on my last few batches.

How do you all hit your desired post boil volumes given everchanging grainbills?

Experience...hah just kidding. Speaking for myself, I just boil to a final volume and vary the boil time. I actually dont even time my boils any more, they usually run 75 minutes plus minus.

Do a test run with just water to determine how much you boil off. Mind you, this will change with the weather conditions. I burn off more in the winter than the summer. It takes practice and a 'feel' for your system to guesstimate how much your pre-boil volume should be. Another variable is the amount of hops your using in a recipe. The hops absorb some of the wort...so when doing an IPA you may need to increase the pre-boil amount. Good notes are essential. I usually shoot for 1.25 +/- ratio for grain/water. I use a marked Ale Pail to catch my runnings from the MLT. Larger grain bills shouldn't mean more wort.... Measure your first runnings. Subtract that amount from your preboil estimate. Divide by two and use that as your sparge water amounts. Getting your pre-boil volumes right will make the post volume amounts easier to predict. I've also found it's easier to hit your OG if your short in the kettle than higher. Adding a bottle of spring water to bring the OG down (and your volume up) is alot easier than boiling longer and screwing up your hop schedule. You won't be able to notice the hop utilization difference.

It's pretty easy, once you've done it about twice. You can plan on starting with 6 gallons or so, and if you boil too much off you can always add some water if your OG is too high.

Your mash thickness should be "set" at the same ratio, but you can vary your sparge volume.

For example, you can use 1.5 quarts per pound of grain. In a 10 pound batch, that's 15 quarts. The grain will absorb about 1.5 gallons (6 quarts) (.1 gallon per pound) so I should get 9 quarts or 2.25 gallons out of the mash. This will change, based on the amount of grain that is used.

Since I'll be getting 2.25 gallons out of the first runnings, and my boil volume will be 6 gallons, I need to sparge with 3.75 gallons to reach the 6 gallons.

The sparge volume can change to reach your boil volume- that's the easiest way to do it.

If you batch sparge, you can draw off your first runnings and measure them to be sure exactly how much sparge water you'll need.

Once you do it a couple of times, you'll know your boil volume and how much dead space you have in your MLT. Everybody's system is different.

bgraham said:

My original problem was coming up with less than 5.5 gallons and lately I've had extra wort given I've just had larger grain bills on my last few batches.

How do you all hit your desired post boil volumes given everchanging grainbills?

Click to expand...

Break the brew process into 2 steps... 1) creating your 'extract' (mashing/lautering), and 2) the boil. You don't go forward with 2 until you get the numbers you want for 1.

If you make sure to always underestimate your mashing efficiency, you should never have a problem reaching your planned preboil gravity and, at minimum, your planned preboil volume. So your first step is to determine how consistent your mashing efficiency is, and undershoot that. The more experience you have, the closer you can get - so the less wasteful you can be. But so long as you never overestimate your efficiency, you'll never have a problem with 'step 1'. If you get a better efficiency than expected (which would give you a higher gravity than planned), you simply dilute w/ plain water until you hit your numbers & then dump out the extra wort to hit your preboil volume.

So - coming into 'step 2', the boil... you have your gravity & volume on lock. Which means that the only thing that could really throw off your post-boil volume and gravity - assuming your calculations are correct and you've accounted for deadspace in your system - is the evaporation rate. In this case, you could hit your numbers whether you undershoot or overshoot the evaporation rate. If you underestimate, you can simply add boiling water near the end of the boil to make up the volume. If you overestimate, you can boil off more. However, a longer boil has the potential to greatly change the character of the beer, and depending on how far off you are, you could be boiling for quite a bit more time than expected. So I suggest you do the same thing as with the mash... underestimate. Just assume an evaporation rate to the point where you're sure you'll boil off at least that much, and make up the rest if required w/ boiling water. Again, the closer you can get at first the less wasteful you'll be. So doing a test boil certainly wouldn't hurt if you don't have a feel for how much you're boiling off now.

Subscribing. I would like to read others' thoughts on this. I am usually pretty consistent with my extract rates (batch sparger). But I have recently increased the size of my brewpot and have had issues with evaporation rate.

I usually collect 7 gallons and go with around an 80 min boil. If I use a full, rolling boil, I will almost always lose more wort than anticipated. I have to keep it at a light boil in order to hit my final volume.

One other "wort stealer" in my process is intentionally self inflicted. My LHBS (both of them) deal almost exclusively in pellet hops. Even with a whirlpool, I have not been able to strain enough pellets out of my wort for my taste. So I have taken to using the disposable mesh bags. Those soak up a significant amount of liquid that robs from my final volume.

winvarin said:

Subscribing. I would like to read others' thoughts on this. I am usually pretty consistent with my extract rates (batch sparger). But I have recently increased the size of my brewpot and have had issues with evaporation rate.

I usually collect 7 gallons and go with around an 80 min boil. If I use a full, rolling boil, I will almost always lose more wort than anticipated. I have to keep it at a light boil in order to hit my final volume.

One other "wort stealer" in my process is intentionally self inflicted. My LHBS (both of them) deal almost exclusively in pellet hops. Even with a whirlpool, I have not been able to strain enough pellets out of my wort for my taste. So I have taken to using the disposable mesh bags. Those soak up a significant amount of liquid that robs from my final volume.

Click to expand...

It's my understanding leaf hops absorb alot more wort, just sayin...

not disputing leaf vs. pellet for liquid absorbption. I use pellet. What I was saying is that in order to reduce the amount of material I have to siphon around/over/through, I use hop bags. I know there is an absorption factor here that I have to account for. I can rarely get leaf hops locally so i almost never use them