The Home Brew Recipe Calculating Program - Mash Temperature Calculator

This is the Mash Temperature Calculator. By entering values for the fields on the screen, this calculator can determine: the required amount of initial water at the entered temperature necessary to hit a mash temp, the required temperature of the initial water at the entered volume necessary to hit a mash temp, the required amount of water to add (infusion) at the entered temperature necessary to boost the mash from one temp to another, the required temperature of the water added at the entered volume necessary to boost the mash from one temp to another, and (finally) the required amount of mash that must be removed, heated to the entered temperature, and then added back to the mash (decoction) to boost it from one temp to another.

Fields

Buttons

Procedures

Formulas

Here are the formulas used by the Mash Temp Calculator. The units used in these formulas are irrelavent so long as they are consistant. The formulas are based on masses, and so return all infusion water/decoction values as a mass. Working with metric here is very helpful since 1 kg of water = 1 liter.

Basic Formula

The following formula will compute the final temperature of a mixture of two masses at different temperatures.

Tf = (Hc1*M1*T1 + Hc2*M2*T2)/(Hc1*M1+Hc2*M2)

Where:

Rearranging this formula, and using a value of 1 for the heat capacity of water, we come up with the following:

Infusion Formula - Amount of Initial Strike Water

The following formula will compute the mass of initial strike water required to hit a certain mash temperature based on the temperature of the initial strike water.

Ma = Hcm*Mm*(Tf-Tm)/(Tw-Tf)

Where:

Infusion Formula - Temperature of Initial Strike Water

The following formula will compute the temperature of the initial strike water required to hit a certain mash temperature based on the mass of the initial strike water.

Tw = (Ma*Tf-(Hcm*Mm)*(Tm-Tf))/Ma

Where:

Infusion Formula - Amount of Step Infusion Water Required

The following formula will compute the mass of the water required to boost a mash from one temp to the next.

Ma = (Hcm*Mm+Mw)*(Tf-Tmash)/(Tw-Tf)

Where:

Infusion Formula - Temperature of Step Infusion Water Required

The following formula will compute the temperature of the water required to boost a mash from one temp to the next.

Tw = (Ma*Tf-(Hcm*Mm+Mw)*(Tmash-Tf))/Ma

Where:

Decoction Formula - Decoction Mass of Mash Required

The following formula will compute the mass of the mash that must be decocted, heated and returned to the mash to boost it from one temp to the next.

Md = (Hcm*Mm+Mw)/(1+((Tf-Td)/(Tmash-Tf)))

Where:

Decoction Formula - Temperature of Decoction Required

The following formula will compute the temperature the decoction must be when returned to the mash boost it from one temp to the next.

Td = Tmash-(Hcm*Mm+Mw)/Md*(Tmash-Tf)

Where:

Fudge Factor

When adding either hot water or decoctions to boost your mash temp, you must always take into account the amount of heat your mash tun will absorb. Typically, this will only be 1 or 2 degrees fahrenheit, but will vary from system to system. After a little trial and error, you will become familar with the temperature drop realized by your system and will be able to adjust for it.

Errors???

I hope these formulas are useful in your brewing endevors. If you find any errors, please, please, please let me know so I may update this page.

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Last Updated: 25-JAN-99