Beersmith Cooling Loss and BIAB Confusion

[geoffm33]

Beersmith tells me I need to "Add 7.91 gal of Water at 161.3F" for my mash. Is it assuming the 7.91 gal of volume is measure at 161.3F?

Because if I have 4% shrinkage figured into my volume loss, and measure my strike water at room temp then I will be off by 4% correct?



Edit to Add:

Using an online calculator (http://www.engineeringtoolbox.com/volumetric-temperature-expansion-d_315.html) I've calculated that 7.91 gallons at 161 degrees is 7.75 gallons at 60° (2% thermal expansion).

From what I can tell, there are no thermal expansion corrections made in the beersmith volume calculations so when you back out 4% or cooling loss, it doesn't make sense to me.

Anyone care to chime in?

 

[1MadScientist]

4% is the total expansion from ambient to boil, so you have 7.756 at ambient and 8.068 at boil.

 

[wilserbrewer]

Just a guess here, but I would think the volumes in beer smith are all referenced to ambient temperature.

While it may seem trivial, I have been bitten by the 4% shrinkage from boil to ambient.


Wilserbrewer
Http://biabbags.webs.com/

 

[Oginme]

I measure the water in cold. I figure that if I am consistent with my measurements the thermal expansion would be accounted for roughly in the grain absorption and the loss during boil, since I measure the finished wort to fermentor and trub loss cold also. It seems to balance out in the long run and I've been hitting my volume targets as calculated by BeerSmith, so....

 

[geoffm33]

Just a guess here, but I would think the volumes in beer smith are all referenced to ambient temperature.

While it may seem trivial, I have been bitten by the 4% shrinkage from boil to ambient.


Wilserbrewer
Http://biabbags.webs.com/

What doesn't make sense to me, is if the volumes are in fact all ambient measurements then why have the 4% cooling loss? If the pre mash and into fermenter volumes are measured at ambient, then there is no cooling loss. A cooling loss is an adjustment to the volume due to thermal expansion/retraction not an actual loss (spillage/grain absorption/evaporation).

Here is a typical batch for me as stated in the Beersmith Volumes Tab:

7.38 gallons (at ambient?)
.53 gallons grain absorption
6.86 water avail from mash

1 gallons boil off

5.86 gallons post boil volume

.23 gallons colling shrinkage
.13 trub loss

5.5 gallon batch size (into fermenter)

If I measure volumes at ambient pre mash and into fermenter, it would appear to me that I will always be 4% over my intended batch size.

Conversely, if the mash water volume is to be measured at ambient then 3 vessel brewers should have the opposite issue. They will fill from the HLT to the mash volume with strike temp water.

I have to be looking at this all wrong, I can't wrap my head around it

Thanks!

 

[geoffm33]

I measure the water in cold. I figure that if I am consistent with my measurements the thermal expansion would be accounted for roughly in the grain absorption and the loss during boil, since I measure the finished wort to fermentor and trub loss cold also. It seems to balance out in the long run and I've been hitting my volume targets as calculated by BeerSmith, so....

My issue is that I am trying to dial in a new system for boil off, grain absorption, etc. So if I am unintentionally increasing my volume by 4% but not my grain bill, due to misunderstanding the cooling loss vis-a-vis BIAB then I would love to correct it.

As I mentioned above, I could be looking at this all wrong and my volume issues lay somewhere else

 

[Pie_Man]

I believe the volumes are at ambient temp and beersmith factors the 4% expansion into your pre-boil volume.

 

[Twang]

Does this help?

From beersmith forum: http://www.beersmith.com/forum/index.php?topic=9021.0

Question: "I would like to know if someone knows if the strike temperature that beersmith indicates is before I heat it or not ? I'm using a seperate kettle for my strike water, so if I heat ~50L at 80°C, I wont have 50L, but something close to 51-52L at 80C. So I can miss strike temperature."

One Reply: "The short answer is that BeerSmith uses hot temperatures for strike, pre-boil and post-boil volume numbers. The yield to fermenter is chilled.

I start all volumes at ambient temperature.

I have a dip stick calibrated for 170 F (in metric I would use 75C) by using weight, rather than volume. The weight of water is constant, where volume changes are not linear by temperature (graph below). It makes more sense to measure volumes near strike/sparge temperature. The volume difference between that and boil temps is about 2%."

 

[1MadScientist]

In Beersmith, the Total Water Needed is based on boiling point, not ambient.

 

[geoffm33]

Thanks 1MadScientist. So for BIAB should I use 4% less water than the recommended Total Water Needed? Assuming I measure it at ambient?

 

[tob77]

FWIW I just set the cooling shrinkage to 0% in my equipment profile. I think that the 4% cooling shrinkage is only useful if you measure your volume while boiling with a sight glass, kettle markings, etc.

 

[1MadScientist]

Thanks 1MadScientist. So for BIAB should I use 4% less water than the recommended Total Water Needed? Assuming I measure it at ambient?

I would yes, because it's a new system. On a 10 gallon batch at flame out you could be off by half a gallon, so it's better to have a higher OG and dilute it down.

Subsequent brews will tell you your boil off rate (because of new pot, diameter) to get an average rate, absorption based on how much you squeeze the bag or don't, etc...other losses (trub)...