Recipe Builder - Water volumes and Use Equipment Boil size?

[Pricelessbrewing]

Trying to make sense of the checkbox on the complete recipe builder, and how it relates to the equipment profile, and the OG calculator and brewhouse efficiency. Comparing it to my other software I think I've figured it out, and just want to double check if this is the intended usage.

Test recipe: https://beta.brewersfriend.com/homebrew/recipe/view/845156/testing

Equipment profile:
Batch Size 42 Gallons
Boil Rate 67 Qt/Hr
Absorption 0.32 qt/lb
Kettle deadspace 16 qt

Working backwards through the volumes
Postboil should be ( 42 gallons + 4 gallon deadspace ) = 46 gallons, or 47.84 gallons at boil temp.
Preboil should be one of the following depending on which volumes are treated with the 4% volumetric expansion coefficient.

62.75 = (46 + 67/4). This is what's listed in the "quick water requirements section" btw, which suggests that water volumes are not treated with the 4% expansion coefficient.

63.42 = 46 + (67/4) * 1.04. This would be if the boil off rate was treated as a HOT measurement.
64.59 = 47.84 + (67/4) , this would be if the kettle losses was a HOT measurement, but boil off was not. This would also apply for any "no chill brewers" that have kettle losses.
or lastly
65.26 = 47.84 + (67/4) * 1.04. For kettle losses and boil off being treated as HOT.

However the only way to get the "correct" OG of 1.071 is to enter a boil size of 58.5-59 gallons, which lines up with the batch size + boil off, and does not include the kettle deadspace which it should. My best guess is that the "Use Boil Size and Boil Evaporation Rate:" checkbox is not accounting for the kettle losses in some way?

Also, when the checkbox is selected, the sigfigs on the OG at the bottom of the fermentables section changes to include 2 decimal points.

 

[Mark Farrall]

snip ...

However the only way to get the "correct" OG of 1.071 is to enter a boil size of 58.5-59 gallons, which lines up with the batch size + boil off, and does not include the kettle deadspace which it should. My best guess is that the "Use Boil Size and Boil Evaporation Rate:" checkbox is not accounting for the kettle losses in some way?

...snip

How is kettle deadspace relevant to the OG? The OG doesn't change if you leave wort in your system, just your efficiency.

 

[Pricelessbrewing]

Because the two volumes, and boil sg / OG don't match.

One is calculating 1.071 OG @ a volume of 42 gallons, with a preboil volume of 62.75 gallons @ 1.051

Then when it's checked it calculating 1.071 OG with a preboil volume of 58.75 gallons @ 1.051. This isn't accounting for the kettle deadspace.

If efficiency is constant, and volume changes, then gravity must also change.

 

[Mark Farrall]

I don't see why you're saying efficiency is constant here. You're leaving wort, therefore sugar/extract, therefore efficiency in the kettle. So the brewhouse efficiency decreases, not the OG.

 

[Pricelessbrewing]

Does that setting disable the user input brewhouse efficiency? In this test recipe it's set to 80.6%.

 

[Mark Farrall]

I think you're right. That setting uses the evaporation rate from the equipment profile and the boil volume. If you're not using that I believe it just calculates OG from batch size and ignores the boil off rate. But I'm not 100%. Maybe something for @Yooper to confirm?

 

[DoubleAbrew]

I think you're right. That setting uses the evaporation rate from the equipment profile and the boil volume. If you're not using that I believe it just calculates OG from batch size and ignores the boil off rate. But I'm not 100%. Maybe something for @Yooper to confirm?

Still trying to make some sense of this. Kettle losses and misc losses and definitely not factored here, but I don't think they need to be. Wort left behind is an efficiency function, not an OG factor.

Anyway, I looked at 3 recipes of mine and the differences between the numbers with this "boil size and evaporation rate" box selected. For reference, my boil off rate is 5 qt/hr or 1.25 gal/hr and my batch size is set to "fermenter". Some points I found:

- PRE-BOIL gravity changes when this box is selected. For both 60 min and 90 min boil recipes, the pre-boil gravity drops an average of .05 when selecting the box. Obviously, this impacts the OG down the line.

- Water requirements do not change based on the selection of this box alone.

- Selecting Batch Size Target to "Kettle" disables the selection of the Boil Size and Evaporation Rate box and changes the water requirements with all others remaining the same.

So, the big question for me is, since my grist bill doesn't change and the water requirements don't change, why would the pre-boil gravity change? What am I missing?

 

[Pricelessbrewing]

Still trying to make some sense of this. Kettle losses and misc losses and definitely not factored here, but I don't think they need to be. Wort left behind is an efficiency function, not an OG factor.

Anyway, I looked at 3 recipes of mine and the differences between the numbers with this "boil size and evaporation rate" box selected. For reference, my boil off rate is 5 qt/hr or 1.25 gal/hr and my batch size is set to "fermenter". Some points I found:

- PRE-BOIL gravity changes when this box is selected. For both 60 min and 90 min boil recipes, the pre-boil gravity drops an average of .05 when selecting the box. Obviously, this impacts the OG down the line.

- Water requirements do not change based on the selection of this box alone.

- Selecting Batch Size Target to "Kettle" disables the selection of the Boil Size and Evaporation Rate box and changes the water requirements with all others remaining the same.

So, the big question for me is, since my grist bill doesn't change and the water requirements don't change, why would the pre-boil gravity change? What am I missing?

Right.

I think the best thing would be 1) Clarify what this setting actually changes, and 2) If this setting is changing the preboil volume, or somehow calculating the batch size based on the preboil volume and the equipment boil off rate, then the Recipes batch size and/or preboil volume should be disabled and show the calculated volume based on the equipment parameters.

 

[Mark Farrall]

Right.

I think the best thing would be 1) Clarify what this setting actually changes, and 2) If this setting is changing the preboil volume, or somehow calculating the batch size based on the preboil volume and the equipment boil off rate, then the Recipes batch size and/or preboil volume should be disabled and show the calculated volume based on the equipment parameters.

Something like that makes sense to me. Just need to work out how to make it more obvious what are the inputs and how they change the nubmers. Maybe something like the water requirements (or an updated version) that shows the effects on the gravity of the various steps and the inputs to the calculations.

 

[Pricelessbrewing]

Alright took another look at this, I think I figured it out.

When you use that check box, the OG formula changes

the Batch size to a calculated volume base on the user input Est boil size, and the equipment boil off rate. This new (hidden) batch size is used to calculate the OG.

Non-displayed batch size = [ user input EST boil size ] - [ Equipment boil off rate ] * [ Recipe Boil time / 60 ] = 7 - 2 * 1 = 5.

Similarly, the preboil volume is simultaneously changed to be the user input batch size + the equipment boil off rate. This new (hidden) preboil volume is used to calculate the (pre) boil gravity.

Non-displayed boil volume = [ user input EST boil size ] + [ Equipment boil off rate ] * [ Recipe Boil time / 60 ] = 5.5 + 2 * 1 = 7.5.

You can see in the table below, that the values all align.

|                                   | Checked | Unchecked  (mismatched) | Unchecked  (matched) |
|-----------------------------------|---------|-------------------------|----------------------|
|  Preboil Gravity                  |  1.041  |          1.044          |         1.041        |
| Boil size                         |   7.5*  |            7            |          7.5         |
| OG                                |  1.071  |          1.065          |         1.071        |
|  Batch size                       |   5.5   |           5.5           |           5          |
| Equipment Boil off rate  (gallon) |    2    |                         |                      |
|                                   |         |                         |                      |

Now the question remains, is this intended @Yooper?

I'm not so sure that it makes sense to change BOTH the batch size, and the boil size. The verbiage should be clarified,and IMO the batch size shouldn't be changed.

If anything, simply change it to a small check box next to "Est Boil size" that says something like "calculate? [ ]", or similar to the brew log (expected 7.5 gallons ).

Or keep it where it is and change the function to just calculate the boil volume, which should disable the user input Est Boil size text box, and update the verbiage accordingly. Something like "Use the equipment profile to calculate the Boil size and boil gravity." and leave the OG based on the batch size which should really be a recipe and user input property.

 

[Yooper]

We made a couple of changes- do you want to take another look and see if the description is better for your usage, and if it is made clearer and more accurate for the way we brew?

 

[Pricelessbrewing]

Below is from the beta.=

The checkbox was removed from the >More section, and changed into a clickable tooltip button next to post boil size. When clicked, it changes the post boil volume to be calculated from the preboil size, and the equipment profiles boil off rate, and the post boil volume is used for the OG and IBU calculations (also SRM/abv/calories etc).

I'm still not sure if this is actually useful in the current state. By definition, OG is the gravity defined at the batch size, and now that the post boil gravity is displayed as well, it's not providing any additional information to change the recipes OG basis. I still vote to remove the association with the recipe stats, and simply make it calculate the post boil volume. "Click to calculate post boil volume from equipment."
Or remove the function, and simply display the expected post, and/or pre boil volumes from the equipment parameters like the brew log shows.

Typo in tooltip for postboil size "Oiriginal". Also it wasn't immediately clear that the tootlip was actually functioning as a clickable element as well, which should be a separate UI element since you can't tell at a glance that is the purpose, or if it's possible to turn it off? My preference would be to move the "gallons" to the left under Boil Size:, then add a check box to the right between post's text box and the tooltip.

The recipe overview section at the top is much clearer, defining pre and post boil volumes, and gravities in the >more batch stats.

I think a classifier on the mouseover tooltip for BU/GU ratio would be nice to specify that it is the IBU / OG and not either of the boil gravities which are shown above it.

Additionally, when the "target' is changed to kettle, the batch size becomes post boil, and efficiency becomes ending kettle (aka mash efficiency) which should be equivalent to the current purpose of the use post boil size for OG formula, correct? (Note: The post boil gravity is not shown in the batch stats when target: Kettle is selected. It

Lastly: Post boil gravity, this should include any "late additions", correct? If I add a sugar addition the gravity contribution is accounted for in the OG, but not the post boil gravity.