The Mash/Lauter Tun (MLT) is used to soak (mash) the grain in hot water (called strike water) to release malt sugars. Sparge water is then used to filter (or lauter) the malt sugar solution from the grain. The strike and sparge water are heated in the Hot Liquor Tank (HLT) as described in the previous article.
As the grain is mashed over time (typically 1-2 hours), the very specific mash temperature(s) are maintained by circulating the liquid (or 'sweet wort') through a HERMS heat exchanging coil in the Hot Liquor Tank. We set the desired temperature on our control panel and the sweet wort is continuously pumped through the HERMS coil to compensate for the heat loss that occurs over time.
A Blichmann false bottom is used in the Mash/Lauter Tun (MLT) to filter the sweet wort from the grain such that only the sweet wort is circulated and heated.
The continuous recirculation also filters the wort naturally using the husks in the grain bed (a process called 'vorlauf'). The wort slowly clears over time as the grain is mashed. We do not use any mechanical stirring devices as they are counter productive and destroy this natural grain filter. After the grain is initially mixed with the strike water, it is never disturbed.
Grain is placed in the Mash/Lauter Tun and is mixed with hot water called 'strike' water. This is recirculated for 1-2 hours through the HERMS coil in the Hot Liquor Tank to maintain temperature. The grains are then rinsed and the resulting sweet wort is pumped to the Boil Kettle.