"Boil Size" calculation

[BelligerentOwl]

Greetings.
I was inputting my recipe into the Grainfather app and it is looking for a Boil Size. I was unsure of what was being factored in so I sent the following email to their helpdesk:

I have a 5 gallon batch with 11 lbs of grain and a 60min boil time on a 110v unit. What should I be entering as my "boil size" in the recipe? Is this just the total of the mash water and sparge water as calculated by your calculator? 4.48gal mash + 2.63gal sparge = 7.11gal?

The response was as follows:
Please remember to account for the 1.3 gallon loss during the boil and thrub.
This might be of use to you : https://www.grainfather.com/brewing-calculators

So where is the 1.3 gallon calculation coming from? I didn't see a loss calculator. What should my boil size be?

Thanks!

 

[Vedexent]

AFAIK - Boil size should be the volume of your strike/mash/sparge water minus the grain absorption volume.

Being Canadian, I figure grain absorption at 1L / Kg of grain which Google converts to 0.479306 quart / # of grain.

There's a good article at figuring water volumes for various stages here.

I think their 1.3 gallons is likely boil loss if I read their response correctly.

Your initial mash volume should be [Water Volume] + [Grain Volume] ( 0.75 L / KG)

Your final mash volume should be [Water Volume] + [Grain Volume] - [Absorption Losses]

Your final wort volume should be [Initial Water(s)] - [Absorption Losses] - [Boil Losses].

I usually work backwards from the amount of beer I want to bottle, figure in trub/equipment losses, figure in boil and grain absorption losses, and then tweak the amount of water I want to start with (some back-and-forth as I tweak grain to get target OG, and then again as adding grain increases water absorption losses).

 

[BelligerentOwl]

Vedexent,

Are you using the 110v Grainfather? It seems to me that the 1.3gal number that they are using is based on some sort of standard for the equipment. If so, I'm not sure if they are saying my number should be:

4.48gal mash + 2.63gal sparge + 1.3gal boil/trub loss = 8.41gal

Or am I subtracting the "loss"?:
4.48gal mash + 2.63gal sparge - 1.3gal boil/trub loss = 5.81gal


I'm new to all-grain so forgive my confusion.

 

[doug293cz]

Vedexent,

Are you using the 110v Grainfather? It seems to me that the 1.3gal number that they are using is based on some sort of standard for the equipment. If so, I'm not sure if they are saying my number should be:

4.48gal mash + 2.63gal sparge + 1.3gal boil/trub loss = 8.41gal

Or am I subtracting the "loss"?:
4.48gal mash + 2.63gal sparge - 1.3gal boil/trub loss = 5.81gal


I'm new to all-grain so forgive my confusion.

(Pre-)Boil Volume = Strike Volume + Sparge Volume - Grain Absorption = Target Fermenter Volume + Boil Loss + Trub Loss

Post-Boil Volume = Pre-Boil Volume - Boil Loss = Target Fermenter Volume + Trub Loss

Grain Absorption = Grain Bill Weight * Grain Absorption Rate

Grain Absorption Rate is typically about 0.12 gal/lb.

Trub Loss is volume left in boil vessel after transferring wort to the fermenter.

You should be able to figure out whatever you need with the above equations and some simple algebra. (Who knew in middle school that algebra would be needed in your future life to brew beer? )

Brew on

 

[Vedexent]

Vedexent,

Vedexent,

Are you using the 110v Grainfather? It seems to me that the 1.3gal number that they are using is based on some sort of standard for the equipment. If so, I'm not sure if they are saying my number should be:

4.48gal mash + 2.63gal sparge + 1.3gal boil/trub loss = 8.41gal

Or am I subtracting the "loss"?:
4.48gal mash + 2.63gal sparge - 1.3gal boil/trub loss = 5.81gal


I'm new to all-grain so forgive my confusion.

I am not using a Grainfather - but I suspect you're right in that the 1.3gal number is a standard "average loss" for that equipment.

That number may change based on a number of factors - most notably your elevation.

If you want to be dead sure as to what your boil loss per hour is, put a measured amount of water in your system, boil for an hour, and measure what comes out.

That will give an experimentally confirmed boil rate for your system/location/situation.

As to your math - if you want 5-ish gallons in the batch, then it's the latter equation - 7.11 gallons of mash/sparge water, after 1.3 gallons boil loss would give you 5.81gal post point.

That would give you ~.81 gal "trub loss margin" which doesn't seem unreasonable.

It will take some experimenting to "dial in" your system and volumes to know what margins you need to use for boil loss, trub loss, and equipment losses.

 

[BelligerentOwl]

Cool - algebra

Is your best guess that when they are asking to input boil size they are asking for pre or post boil volume? Neither?

It's a heck of a thing to figure trub loss when you are brewing on the system for the first time and it's your first all-grain. Their response of "Please remember to account for the 1.3 gallon loss during the boil and trub." is pretty specific! It's seeming like they want you to use their calculator to figure sparge and strike water (fine) and then they are using a grainfather-specific calculation to get the 1.3gal. Again, not sure if they want that number subtracted or added back.

I appreciate your patience Vedexent!

 

[Vedexent]

Cool - algebra

Is your best guess that when they are asking to input boil size they are asking for pre or post boil volume? Neither?

It's a heck of a thing to figure trub loss when you are brewing on the system for the first time and it's your first all-grain. Their response of "Please remember to account for the 1.3 gallon loss during the boil and trub." is pretty specific! It's seeming like they want you to use their calculator to figure sparge and strike water (fine) and then they are using a grainfather-specific calculation to get the 1.3gal. Again, not sure if they want that number subtracted or added back.

I appreciate your patience Vedexent!

Boil size is pre-boil volume.

And yes - it will take a time to "dial in" your process with a combination of experimentation and experience - "What's my real boil rate?", "How much trub do I leave behind in my fermentor?", "What are my equipment losses". Almost everyone's situation is slightly different.

The happy part is that it's tough to render beer undrinkable (although I'd definately recommend - from personal experience - that you pay some serious attention to your yeast and fermentation temperatures).

You might not get it dead on. You might not get the exact results you expected/hoped for.

But chances are you'll still make beer - and it'll be OK