Heating a Mash Tun


Let’s say you have an infusion style mash/lauter tun made from a converted picnic cooler. Over the one hour mash period, it will cool down a few degrees if no more hot water is added. However, adding hot water to a single infusion mash is not usually done. It can thin out the water to grain ratio making it harder for the enzymes to get to the starch. It increases the risk of denaturing the enzymes because a thinner mash means there is more water to come in contact with the enzymes.


An efficient way of maintaining the temperature is to hold back a portion of the infusion water, heat it hotter than the mash temperature, and add it as needed. Of course, since there will be less strike water initially, it will have to be a few degrees hotter than intended to hit the mash temperature. Another way is to heat the mash directly without adding water.


To do this, I use my lower wattage hot stick. I made mine with an “L” design so the whole element can be submerged in the mash. A stick version can work if your mash tun is taller than it is wide – like a round Gott drink cooler. The key to this method is constant movement of the element to avoid scorching the grain. I submerge the heating element in the mash and gently (with little surface agitation) but briskly move it in a vertical circular motion over and over moving from one side to the other and front to back. My mash increases about a degree F per minute. Stop and take its temperature so you don’t overshoot your goal. If the tip touches the side of the cooler, that is alright. As long as you keep it circulating, it will not melt the plastic. Before you remove the hot stick from the mash, turn off the power and continue the circular motion for about 5 seconds allowing it to cool down. Then remove it, gently knocking off the attached grain, and rinse. It is much easier to clean immediately than to allow it to dry.






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