Hitting Post Boil Gravity

[corypedia]

Hoping someone may be able to help me figure out why i keep missing my post boil gravity, or what things impact it.

My last two batches, i've been using BS2 and followed it's instructions. BS2 estimated my pre-boil starting gravity to be 1.051 and 1.050, and my post-boil gravity to be 1.058 and 1.057. My measured gravity pre-boil was spot on for my first batch at 1.051 and the second batch was 1.049. However, post boil my gravity's where 1.069 for both.

I have BS2 setup to use my equipment profile which includes my estimated boil offs and my water usage has been pretty close as well.

Why am I missing my post-boil gravity by so much? Any ideas on where to start?

 

[LLBeanJ]

Sounds like your post-boil volume is less than you think it is or your pre-boil volume is more than you think it is, or a combination of the two. How are you measuring volumes?

 

[brewbama]

Are you boiling off more than your est?

 

[corypedia]

Both my mashtun (igloo cooler) and brew kettle (spike) have markings, which i've measured out and verified to be accurate. I guess it only makes sense though, that my boiloff rate is higher than i have set in BS2...right?

 

[porterpounder]

If your volumes are correct then, yes, you are either boiling harder than you expected or your post-boil measurement is off. Make sure you stir the wort before gathering your sample as it will stratify when cool.

 

[corypedia]

I take my pre and post boil gravity using a hydrometer and refractometer. pre-boil it is done after all wort is collected from the mashtun and a gentle stir. the post-boil is done after cooling the wort and using a drill attachment to oxygenate the wort.

will check my boil-off numbers in BS2 and test my equipment for accuracy of those numbers. thx

 

[corypedia]

Out of curiosity though, say my boil off rate is higher...how will this effect my process?

Using more water to mash will lower my efficiency and boiling for a shorter period than an hour would affect my bittering hops...

 

[LLBeanJ]

Out of curiosity though, say my boil off rate is higher...how will this effect my process?

Using more water to mash will lower my efficiency and boiling for a shorter period than an hour would affect my bittering hops...

You wouldn't mash with more water, you would just use more sparge water to increase pre-boil volume. Increasing your sparge volume will likely increase your efficiency due to more rinsing of sugars from the grains.

 

[corypedia]

You wouldn't mash with more water, you would just use more sparge water to increase pre-boil volume. Increasing your sparge volume will likely increase your efficiency due to more rinsing of sugars from the grains.

Gotcha

 

[doug293cz]

Out of curiosity though, say my boil off rate is higher...how will this effect my process?

Using more water to mash will lower my efficiency and boiling for a shorter period than an hour would affect my bittering hops...

More mash water will NOT lower efficiency. If anything, it will improve efficiency (ref: http://braukaiser.com/wiki/index.php?title=Understanding_Efficiency#Mash_thickness.)

Efficiency is determined only by the percentage of the available (potential) sugar that you actually end up with in your BK or fermenter. The volume of water mixed with the sugar does not affect the efficiency. More water can help with efficiency if it is added in a way that rinses more sugar out of the grain. More water will reduce SG, but lower SG by itself does not imply lower efficiency.

If you use more water, you will probably need to boil longer (or more vigorously) to achieve your post-boil target volume and/or OG.

Brew on

 

[tsl346]

Are you correcting for temperature when your taking your measurements? If you are taking pre-boil measurements at 170 and taking post boil measurements after you have cooled down your wort to 80 it could make a big difference. It would make sense because if you are measuring at a higher temp than your hydrometer is calibrated for it will give you a lower reading than what your actual specific gravity it. Meaning, you are probably just getting higher efficiency than you are expecting.

 

[kh54s10]

You talk of the mash tun and BK as having volume markings verified as accurate. Do you know the volume of the wort going into the fermenter. If you are boiling off more, thus getting less wort into the fermenter the gravity will be higher.

Measurement temperatures are also a place to look.

 

[C-Rider]

Hoping someone may be able to help me figure out why i keep missing my post boil gravity, or what things impact it.

My last two batches, i've been using BS2 and followed it's instructions. BS2 estimated my pre-boil starting gravity to be 1.051 and 1.050, and my post-boil gravity to be 1.058 and 1.057. My measured gravity pre-boil was spot on for my first batch at 1.051 and the second batch was 1.049. However, post boil my gravity's where 1.069 for both.

I have BS2 setup to use my equipment profile which includes my estimated boil offs and my water usage has been pretty close as well.

Why am I missing my post-boil gravity by so much? Any ideas on where to start?

since your post=boil SG is higher than BS2 figures I'd say you are boiling off more which will concentrate the sugar. But why complain about a higher SG? Just means you are getting more alcohol for your dollar if the ferment goes well.