Pre-boil volume?

[petrolSpice]

Going to be doing my first full boil brew, but still extract. I'd like to end up with 5.25gal after the boil, and I'll be using 7.5lb of LME in this recipe. The kettle is a 11 gal one from Bayou Classic.

What percentage boil-off should I expect per hour? I'll have to factor in the volume of the LME as well.

Thanks

 

[W0rthog]

I'd guess about 1 gallon an hour. Give or take a bit.


Sent from my iPhone using Home Brew

 

[dsaavedra]

Throw a couple gallons of water in your pot and bring it to a boil for an hour and measure how much you boiled off. It's really the only way to get a good estimate for your particular system. No need to bring a full 7+ gallons to a boil just to measure boil off rate, as the rate should stay constant regardless of volume because once water reaches 212 it boils (smaller volume will just reach a boil faster, it will not actually boil off faster).

Edit: I just bought that same pot off Amazon! Did you get the one with the steamer basket too? I did and I may steam crabs in it over the summer.

 

[petrolSpice]

Throw a couple gallons of water in your pot and bring it to a boil for an hour and measure how much you boiled off. It's really the only way to get a good estimate for your particular system. No need to bring a full 7+ gallons to a boil just to measure boil off rate, as the rate should stay constant regardless of volume because once water reaches 212 it boils (smaller volume will just reach a boil faster, it will not actually boil off faster).

Edit: I just bought that same pot off Amazon! Did you get the one with the steamer basket too? I did and I may steam crabs in it over the summer.

Good idea to measure the boil off. I got mine off Amazon too, showed up today. It's a nice piece! I did not get the basket, have no real need for it.

 

[william_shakes_beer]

Good idea to measure the boil off. I got mine off Amazon too, showed up today. It's a nice piece! I did not get the basket, have no real need for it.

The steamer basket provides a really good handle if you choose to mash with grains in a bag. Wish I had one for my Blichmann!!!

 

[petrolSpice]

The steamer basket provides a really good handle if you choose to mash with grains in a bag. Wish I had one for my Blichmann!!!

If (when) I switch to partial mash or all grain I suppose I'll pick up the basket.

 

[dsaavedra]

Yeah my main reason for getting the one with the basket was for doing BIAB, I figured the basket would make a nice handle and it would give me peace of mind about my grain bag not bursting. It was also much cheaper, only about $20 extra for the pot with the basket, v.s. buying the basket separately for $40-$60.

 

[CKing]

A 7 gallon pre-boil volume consistently nets me 5 - 5.25 gallons of bottled beer based on a 75 minute boil and accounts for all losses incurred from start to finish.

 

[RmikeVT]

I have a megapot 1.2 which is about the same dimensions and I lose about 1g/hour. I wouldn't worry about setting up a test and wasting an hour of your time and burning up $$ in propane. Instead put the time to use making beer. Plan for 1g boil-off and take a volume reading before boil and after boil, take notes and adjust accordingly. If you boil off .75g you get .25g extra beer if you boil off 1.25g you can just add some top off water to get to your desired volume.

 

[petrolSpice]

Thanks Mike. I was planning on 1gal/hr for my first brew and then seeing how it turns out. If too much boils off I'll add some top-off water. Not enough boils off I'll have more beer.

Going to try out a 15 minute boil recipe which means I'll lose about 0.25 gal, but I'm adding 7.5lb of LME, or about 0.6 gal (using 10.5 fl.oz/lb).

So 5.25 + 0.25 - 0.6 = 4.9 gal for my pre-boil volume.

 

[dsaavedra]

Thanks Mike. I was planning on 1gal/hr for my first brew and then seeing how it turns out. If too much boils off I'll add some top-off water. Not enough boils off I'll have more beer.

Going to try out a 15 minute boil recipe which means I'll lose about 0.25 gal, but I'm adding 7.5lb of LME, or about 0.6 gal (using 10.5 fl.oz/lb).

So 5.25 + 0.25 - 0.6 = 4.9 gal for my pre-boil volume.

I'm not sure if that math works out. I could be wrong but I would think the fact that extract dissolves in water means it doesn't contribute to your volume. Does anybody know if this is actually the case?

 

[petrolSpice]

I'm not sure if that math works out. I could be wrong but I would think the fact that extract dissolves in water means it doesn't contribute to your volume. Does anybody know if this is actually the case?

When you dissolve extract it water it does not disappear. The two volumes will sum to the new volume, or pretty close.

I'm going to add another 1/2 gal or so to the pre-boil volume to account for trub loss, so that puts me at 5.4 gal.

 

[dsaavedra]

When you dissolve extract it water it does not disappear. The two volumes will sum to the new volume, or pretty close.

I'm going to add another 1/2 gal or so to the pre-boil volume to account for trub loss, so that puts me at 5.4 gal.

Maybe LME will add a little bit of volume because it contains a certain percentage of water, but something like DME wouldn't add much in the way of volume at all I think. It's like how you can dissolve a full 5oz of priming sugar (which probably occupies a volume more than 1 cup) in 1 cup of boiling water without changing the volume. When it is dissolved, the crystalline structures that make the sugar occupy volume are broken down and you just have dextrose molecules floating around in water. Sure it might occupy some volume because like you said it doesn't just disappear, but it is probably not even noticeable to the naked eye and I wouldn't count on it adding enough volume to allow you to start with less water than you intend to end up with.

I would do some searching around on the forums or maybe even set up some little trials before you go boiling 4.9 gallons of water and expect to get 5.25 gallons of wort out of it.

 

[ajf]

If you take 1 lb LME, and mix with sufficient water to make 1 gallon, you will end up with a solution with a SG of 1.036 (according to Beersmith).
This means that the weight of the solution will be 8.3378 lbs * 1.036 = 8.638 lbs.
As you added 1 lb LME, the weight of water that you added would be 7.3378 lbs, or 0.88 gallons, so 1 lb LME occupies a volume of 0.12 gallons.

-a.

 

[Puddlethumper]

There are several factors that affect the boil-off loss including the dimensions of your kettle, the relative humidity, ambient temperature and the altitude where you live. The only way to get a good approximation for future brews is to do a trial run as suggested above. Although some of the variables will change with the seasons, you will get a good "rule of thumb" to help you get a grasp on your particular rate. Over time and experience you'll probably fine-tune this to a pretty accurate figure.

 

[petrolSpice]

Brewed today and decided to use 6 gal for pre-boil volume. The boil was only 15 mins and I added 7.6 lb of LME. I ended up with 5.75 gal in the fermenter with 1/8-1/4 gal of leftovers in the kettle.

I wrapped the wort cooler in a 5 gal paint strainer bag and siphoned the wort out of the center of the wort cooler into the fermenter. Worked very well to keep the hop material in the kettle so I got almost all of the liquid out of the kettle.