Is there a formula to calculate the temperature drop when adding the grains?

[Yirg]

Suppose I have 10 kilos of malted grains at room temperature (for the sake of the discussion, 20°C) and I'm adding them to 30 liter of hot water. What temperature should the water be so that the impact of the relatively colder grains would bring it down to mashing temperature (i.e. 68°C)?

This seems like a simple equation, but the last time I tried it, I failed badly. Despite the significant mass of the grain the temperature hardly dropped and I ended up with too hot a mash.

Any suggestions?

 

[Pkrd]

A few degrees drop is about right...

Theres a bunch of calculators online that will do this for you...
eg http://biabcalculator.com

 

[Chris_Primavera]

None of the calculators I have used gets it exactly right.

Be careful taking your measurements, keep good records and you should be able to dial in your system in a couple of batches. If unsure, undershoot and add heat to get to your mash temperature.

 

[Yirg]

Thank you both. According to the calculator, with my parameters the drop will be about 1°C. Way less than I expected. I think I can simply aim to get the water to the upper limit (e.g. 70°C), add the grain, then let it drop by 1°C or whatever the drop is, as long as I don't reach the lower limit (68°C). Sounds simple enough

 

[kombat]

I believe most of the users of HBT are based in the USA, and thus are more familiar with imperial measurement units. Even those of us outside the US, living in otherwise metric countries (such as myself, in Canada) are more familiar with imperial measurement units, if only because the majority of recipes and guidelines seem to be quoted in them. As such, you'll likely get better responses if you ask your question in units more of us are familiar with.

You're mashing 22 lbs of grain in 8 gallons (32 quarts) of water, for a mash ratio of 1.45 qt/lb, which is fine. Your target mash temperature is 154° F. As mentioned, the calculators will help you get close, but the most accurate way is simply to practice on your own system and carefully note the temperatures as you calibrate things. On my system, I generally aim for my strike water to be 12° F above my target mash temperature, and that gets me pretty much bang-on, every time. A loss of only 1° C sounds like a considerable underestimate. I think you'll find your mash will lose much more heat than that as you stir in your grains, but as I said: try it, measure it, and see.

 

[Natdavis777]

Brew365.com has a good Mash/Sparge Calculator that incorperates temp loss when doughing in. As for my system, I lose 12 degrees F after preheating my MLT. So for a 152F mash, I dough in @ 164F. If you dont preheat your MLT, the walls of the cooler/keggle/pot/etc can leach some of the heat and cause a drop or lower than expected mash temp.

 

[henryred]

I find run the water a few hotter. Add to run with out grain. Let it hit 168 f and mix in grain. It will drop to 154. More consistent than adding hot water to grain and cold tun