Mash tun dead space

The BREWHA Mash Tun has been designed with increased space under the screen in order to include an element to provide precise temperature control for best mash efficiency and quality. Although its technically not 'dead space' as the wort is fully cycled through it does raise a question, namely, is a larger volume of space under the mash screen a bad thing?

The main reason given for not wanting a large space under the mash screen is that it will throw your strike water volume calculation off. If you don't know the volume of this 'dead space' you may underestimate the volume of water you need in order to attain the proper water/grist ratio to fully remove the sugars from the grain during mashing. But this really isn't a problem at all for if you know your volume under the screen, the ratio is easily fixed. If your space under the screen is 4L (1 gallon), add an extra 4L to your strike water you add to the grain. If 10L, add 10L extra.

A second argument for small space under the sceen is that it would leave valuable sugars/wort in the mash tun once the wort has been transferred to the boil kettle. But this is readily solved by BREWHA as the mash tun has been designed with a pickup tube that drains the wort to within a few millimeters of the bottom of the mash tun, leaving virtually no wort behind.

stainless steel pickup tubeA third argument for small space under the screen is that since the exit port is on one side of the vessel, a large volume under the screen will fail to cycle the wort out from the opposite side of the vessel during vorlauf creating a 'dead space' in the back of the mash tun. (Vorlauf is the process of moving wort from the bottom of the mash tun to the top in order to remove the cloudiness of the wort and help improve mash efficiency). The pickup tube in BREWHA's mash tun also addresses this issues as the tip of the pickup tube is under the screen near the center of the mash tun so the wort is pulled from all sides of the vessel, not just the side nearest the exit port. 

So as we see it, with a proper understanding of how to adjust your volume calculations for strike water, BREWHA's inclusion of a port for a heating element and thermowell under the mash screen in order to be able to provide precise temperature control was a very worthy trade-off for a little extra volume under the screen. Many benefits gained, several problems solved.

stainless steel mash tun with Ultra Low Watt Density ULWD electric heating element under the high efficiency mash screen



  • Thank you for your question Ken.
    Since mineral/salts affect pH in a quantifiable manner, with a known volume of water and an understanding of that water (ie. ppm of the various salts) you can accurately predict your mash pH whether you have a small or large volume of water. That is to say, a given quantity of salts will have the same buffering capacity on a given quantity of grain, whether it occurs in 5 gallons or 10 gallons of water. Water profile tools like those available with the Beersmith program can easily make those calculations for you.

    BREWHA Equipment Co
  • Fourth argument: mash chemistry. Will the extra water make it harder to hit my target mash PH?

    Ken Gough

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