Grainfather water calculation

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meirion658

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Good afternoon all,

Decided to do a 19L california common today and used the grainfather app to build the recipie.

Mash 16L
Sparge 12.5

On transferring to the FV I was around 3 liters short!!!

I decided to have a look at the grainfather water calculator on their website which gave a totally different water volumes!!

Mash 20L
Sparge 13.5

Why would the website give a totally different readings to the app.
 
33.5 total liquor sounds toppy for 19L. How many kg of grist? How long did you boil? Most of my hour boils on GF I reckon about 31L total for 21L in FV for standard gravity beers/ hop bills.
 
33.5 total liquor sounds toppy for 19L. How many kg of grist? How long did you boil? Most of my hour boils on GF I reckon about 31L total for 21L in FV for standard gravity beers/ hop bills.

I had 5kg of grist and a boil time of 70min.
 
Yeah, I just did it manually and get Steve's numbers, except I forgot you boiled 70 mins which adds an extra half litre. Something that gets me is the fact that wort at 20c is 96% the volume of it at 100c, doesn't sound like much but it's basically a litre when you've got +/- 20 L post-boil.

2.7 L/kg x 5 kg + 3.5 L = 17 L mash
19L + 2 L (DV) + 3.5 L (boil) = 24.5 L pre-boil
24.5 L - 17 L + (0.8 x 5) L (grain absorption) = 11.5 L sparge
 
I had 5kg of grist and a boil time of 70min.

In case you need a breakdown of the water calcs for a G30 Grainfather here they are, it's nice to know where the figures come from .......

Mash volume = (Grain Weight in KG * 2.7) + 3.5
Sparg volume = (preboil volume - mash volume) + (grain bill in KG x 0.8)
Boil off loss = 3L per hour (0.05L per minute) for a 230V Grainfather
Preboil volume = (0.05 * boil time in minutes)) + trub loss(2L) + batch size


An example **** 5KG grain bill, 19L batch size, 70min boil time ****

The preboil volume for a 70min boil is 19L + (0.05 * 70mins)) + trub loss(2L) = 24.5L

Mash volume = (Grain Weight in KG * 2.7) + 3.5
mash volume = (5 * 2.7) + 3.5 = 17L

Sparge volume = (preboil volume - mash volume) + (grain bill in KG x 0.8)
Sparge volume = (24.5 - 17) + (5 * 0.8) = 11.5L

total water volume = mash volume + sparge volume
total water volume = 17L + 11.5L = 28.5L


As has been already said you can always use the grainfather calculater on their site to check that you are getting the figures correct when creating a recipe. If there is a descrepancy then I would check your equipment profile. You can always genarate a new default equipment profile, there is a nice little wizard on the grainfather site to do that.
 

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