Mash Water Chart for using 1 quart per pound of grain assuming the Cp (specific heat) of grain to

Click here to view the chart

Background:
Initially I wanted to take data from my system and empirically derive a formula for the temperature loss specific to the equipment that I use. Then I thought about trying to use the theoretical formula for heat transfer between the grain and the malt and see how well it fit. It fit very well.

The formula is: Ti=[(Mw*Tf)-(Cp*Mg*dT)]/Mw
Ti = initial strike water temperature
Mw = mass of initial strike water
Tf = final temp desired
Cp = specific heat of grain (0.4) -- Cp is BTU/lb-degF
Mg = mass of grain
dT = is the change in temperature of the grain (dry grain temp - Tf)

I typically use between 30 and 40 pounds of malt for a batch. This amounts to between 90 and 125 pounds of mash. I think the reason that the theoretical seemed to fit so well with my system was because the percentage of heat I lost to the air and to the mash tun when initially mixing the mash is small enough to be neglected.

How to use the chart:
I would suggest trying the data from this chart once and note whatever difference in temperature you get between the theoretical combined temperature and actual combined temperature. Then the next time you brew, use that temperature difference as a "correction factor" meaning; use the chart to find out the theoretical hot water temperature needed and then add your correction factor to that theoretical temperature.

There are other enviromental variables but since we are dealing with a fairly small temperature range of the malt and target mash temperature, the "corrected temperature method" should be accurate for your system. If not, just keep playing with your correction factor until you get it right. The differences should only be a few degrees anyway (assuming that you heat your insulated mash tun with hot water, stir quickly and cover).

I hope that this will make hitting that target temperature easier for you. Please let me know what your results are. Have fun!

© 2000 by Dan Kiplinger
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