Low brewhouse efficiency

[xben]

Hi,
I brewed my 4th all grain batch yesterday. Using beersmith for all my previous batches, my equipment profiles are getting very close to reality. All the batches I made so far were giving me a mash & brewhouse efficiency of 65% & 57%. This time, I decided to try malt conditioning and crush finer, while designing my recipe with 60% efficiency. The worst that could happen is to finish with higher alcohol..

The results :

Estimating pre-boil gravity : 1.054 (60% mash eff.)
Measured pre-boil gravity : 1.066 (75% mash eff.)
Estimated & measured pre-boil volume : 6.6 gal. (right on number)

Boiled 1 hour.....

Estimated OG : 1.070 (60% brewhouse eff.)
Measured OG : 1.073 (60.8% brewhouse eff.)
Estimated batch size : 5 gal.
Measured batch size : 4.9 gal (almost on...)

So, according to beersmith, the boiling should give me a rise of 16 "points" of gravity, but I only got 7.. before I start the boil, I expected to have an OG of at least 1.080.

Any idea of what's wrong? I read the hydrometer and sample temp. at least 5 times to BE SURE the reading was good!

Thank you!

 

[billl]

Are you cooling the wort before taking a gravity reading? Are you leaving any liquid behind in the brew kettle?

 

[BrewKnurd]

Hi,
I brewed my 4th all grain batch yesterday. Using beersmith for all my previous batches, my equipment profiles are getting very close to reality. All the batches I made so far were giving me a mash & brewhouse efficiency of 65% & 57%. This time, I decided to try malt conditioning and crush finer, while designing my recipe with 60% efficiency. The worst that could happen is to finish with higher alcohol..

The results :

Estimating pre-boil gravity : 1.054 (60% mash eff.)
Measured pre-boil gravity : 1.066 (75% mash eff.)
Estimated & measured pre-boil volume : 6.6 gal. (right on number)

Boiled 1 hour.....

Estimated OG : 1.070 (60% brewhouse eff.)
Measured OG : 1.073 (60.8% brewhouse eff.)
Estimated batch size : 5 gal.
Measured batch size : 4.9 gal (almost on...)

So, according to beersmith, the boiling should give me a rise of 16 "points" of gravity, but I only got 7.. before I start the boil, I expected to have an OG of at least 1.080.

Any idea of what's wrong? I read the hydrometer and sample temp. at least 5 times to BE SURE the reading was good!

Thank you!

You mentioned that you read the sample temp at least 5 times... but not what the sample temp was or if you corrected for it.

Anyways, depending on what temp the wort was when you measured it, your 6.6 gallons preboil could be anywhere from 6.3 (if the 6.6 was at boiling temp) to 6.6 (if the 6.6 was measured at room temp) gallons at room temp. Boiling that down to 4.9 gallons (assuming room temp for final gravity) would be anywhere from 1.085 to 1.089 post boil gravity, and you were nowhere close to that.

I notice you have a brewhouse efficiency set equal to mash efficiency in your estimated numbers. So you get every drop from the kettle into the fermenter? Not saying you don't, certainly lots of people dump everything from the kettle to the fermenter, just pointing out that if you don't, that's where you can lose some sugars.

Put another way, you can only directly relate a change in volume to a change in gravity if all of the change in volume is due to boiloff. Otherwise you need to do some extra math to account for the loss of volume to other factors.

I hope that made sense.

 

[peterj]

The numbers you gave aren't adding up right. If you boiled 6.6 gallons of 1.066 wort down to 4.9 gallons you would have to have an OG of around 1.089. But like BrewKnurd said, your post just says 4.9 gallons into the fermenter. Using a boil off calculator I figured that if you went from 1.066 to 1.073 that means you only boiled off about 0.6 gallons. Did you leave 1.1 gallons in the kettle? Another alternative is that maybe your preboil gravity wasn't accurate. Did you thoroughly mix your wort?

 

[xben]

I corrected all the readings to 60F, as specified by the hydrometer specifications.

My boiling kettle is actually the same setup as my mash & lauter tun, which is a 8.5 gal SS kettle, equipped with a 12-in bazooka filter & valve. I basically mash, dump the wort into a 2nd container, clean the kettle and re-dump the wort back to start the boiling process.

I took my OG after the cooling, just before dumping into the fermentor, so the sample temp was close to room temp. I use the same bazooka filter to dump the wort into the fermentor, so any "solid" (hop residues and other sh**) stay into the kettle.

Are you telling me I should not use the filter and dump everything into the fermentor?

 

[billl]

"I corrected all the readings to 60F, as specified by the hydrometer specifications."

Those corrections only work work on a very narrow range of temps. Did you cool the mash sample you tested?

You can sift out as much hop and break material as you want, but you need to account for it. If you are making something like a IIPA, you could lose a LOT of volume/sugar to absorption by the hops.

 

[xben]

The numbers you gave aren't adding up right. If you boiled 6.6 gallons of 1.066 wort down to 4.9 gallons you would have to have an OG of around 1.089. But like BrewKnurd said, your post just says 4.9 gallons into the fermenter. Using a boil off calculator I figured that if you went from 1.066 to 1.073 that means you only boiled off about 0.6 gallons. Did you leave 1.1 gallons in the kettle? Another alternative is that maybe your preboil gravity wasn't accurate. Did you thoroughly mix your wort?

The pre-boil gravity should be right because the wort was transfered twice before I took the reading. But, the OG sample was taken before it was dumped into the fermentor. Maybe I should dump before and take the sample after, to mix everything?

 

[BrewKnurd]

The pre-boil gravity should be right because the wort was transfered twice before I took the reading. But, the OG sample was taken before it was dumped into the fermentor. Maybe I should dump before and take the sample after, to mix everything?

If it just got done boiling, everything is already mixed (unless you've added extra water post boil, which it doesn't sound like).

As far as dumping everything into the fermenter, no one is saying you have to or should, merely that whether you do or not factors into the calcs.

For instance, lets assume you had 6.6 gallons, with volume measured at the same temp the hydrometer reading was taken. Then you had 436 gravity points (1.066 - 1) * 6.6. The gravity points stay constant through the boil.

So now you boil and cool your wort to get to 6 gallons post boil. Your gravity now, since gravity points are constant, will be 1.073. You lose 1.1 gallons because you have a lot of trub/hops/run out of space in fermenter/whatever, however it happens, that you end up with 4.9 gallons in the fermenter. You will have 4.9 gallons of 1.073 wort that will be the basis for calculating brewhouse efficiency.

Alternatively, you could boil your wort harder, boil off 1.7 gallons so that you end up with 4.9 gallons post boil. Your gravity in this case will come out at 1.089. You dump all of that, break material, hops, etc into the fermenter. You will have 4.9 gallons of 1.089 wort that will be the basis for calculating brewhouse efficiency (as it is typically measured, based on volume and gravity into the fermenter. I would argue that one would be lying to oneelf a bit in regards to efficiency here, as you know that some of what you transfered is not in fact liquid ).

All of which is just to harp on the point that you can do it either way. But just knowing the volume you started with and the volume that went into the fermenter doesn't allow for answering the question of if the gravities make sense.

hope this helps.

cheers,
nathan

 

[xben]

So, if I understand well, if I would transfer everything to the fermentor, I would have a total volume of 6 gallons (liquid+trub) of 1.089. Does the yeast "eat" sugars "hidden" into the solids? Then, any solid would be a part of the yeast cake to finally ends with my 4.9 gallons of solid.

Is this right?

 

[BrewKnurd]

So, if I understand well, if I would transfer everything to the fermentor, I would have a total volume of 6 gallons (liquid+trub) of 1.089. Does the yeast "eat" sugars "hidden" into the solids? Then, any solid would be a part of the yeast cake to finally ends with my 4.9 gallons of solid.

Is this right?

Nope. First of all, the way you're saying it makes it sound like the post boil gravity is a function of whether you transfer everything or not. Its not. Whether you transfer everything, or leave something behind, has an impact on brewhouse efficiency, and has an impact on how you would calculate your estimated numbers, but doesn't have an impact on the actual gravity once the boil is over. The actual post boil gravity is only a function of the gravity before the boil and how much you boiled off.

In order to get to 1.089 from 6.6 gallons of 1.066, you need to boil off 1.7 gallons.

cheers,
nathan

 

[billl]

"So, if I understand well, if I would transfer everything to the fermentor, I would have a total volume of 6 gallons (liquid+trub) of 1.089. Does the yeast "eat" sugars "hidden" into the solids? Then, any solid would be a part of the yeast cake to finally ends with my 4.9 gallons of solid."

No. You won't get 6 gallons of 1.089. The gravity isn't going to increase just from dumping it from 1 container to another.

The gravity is only going to go up if you concentrate the sugar by boiling off more water. If you lose some wort to trub, hops etc you are losing both water and sugars.

 

[xben]

Thank you for your clear answers!

The only possible solution is now that the estimated numbers are wrong because they are calculated from my equipment profile numbers, which are probably wrong too.. so I need to fine tune them.

Happy holidays, cheers!