Bottoms_Up
Well-Known Member
Thanks @micraftbeer, you have completely understand what I was trying to point out. It's good that Brewfather can be tricked into accommodating the excess space by using the "recoverable mash deadspace" profile option. I assume that most people using this "deadspace" would just add the space below the mashpipe and that's why I specifically mentioned the space around the mash pipe, because I don't think that most homebrewers are aware that that amount should also be added. Even if they were aware, I assume that they would likely have thought it to be negligible, as I used to. For their benefit, I have calculated that amount to be 18% of the volume within the mash pipe independent of the mash thickness. The volume includes both the infusion water plus the grain. There is a mathematical way this volume can be calculated fairly easily, which involves the displacement of the grain as well as the amount of water the grain absorbs.I use Brewfather. Its equipment profiles have two terms relative to this:
1. Mash Tun Deadspace. It explains this as recoverable mash deadspace. Brewfather uses this mathematically like this... You define your desired mash thickness in qt/lb (in the Brewfather equipment profile), and it calculates a mash water volume. Then it adds this Mash Tun Deadspace value and this is the total volume of water Brewfather tells you to put in your "mash tun". In this case, that's just how much to add to your BrewZilla. I have 0.66 gallons in my profile for BrewZilla Gen4.
2. Mash Tun Loss. It calls this unrecoverable mash volume. This is wort left behind in your "mash tun" that doesn't make it into your "boil kettle". Mathematically, Brewfather takes your amount of Mash water added above, subtracts off the grain absorption (my profile has 0.479 qt/lb), then subtracts off this Mash Tun Loss to give you your pre-boil volume. Since BrewZilla mash tun = boil kettle, I have Mash Tun Loss set to 0.
Here's an example of my most recent brew:
- 3.8 Gal of mash water
- 10.3 lbs of malt
- Target 1.25 qt/lb mash thickness
- 3.6 Gal of sparge water
- Measured 6.76 Gal of pre-boil volume
- Measured pre-boil gravity of 1.049
- Measured 82.8% mash efficiency
In short, you add the grain volume to the volume of infused water, minus the volume absorbed. The mash grain displacement is 0.36 qt./lb. or 0.75 liters/kg. The water absorption ratio for grain is 0.10 gallons/lb. or 0.379 liters/lb. Once you calculate the volume, the recoverable dead sapce around the mash pipe (but not below it) is 18% of that volume. Then you add the volume below the mash pipe, which, for the 35 liter Gen 4 is 2.0 liters (0.53 US Gallons).
For a typical 5 gallon brew, according to my calculations, the total recoverable mash deadspace is about 4.3 liters or 1.14 US gallons. Thus your 0.66 gallons seems quite low.
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