This is the Biohazard Brewery constructed by PBS Brewing Systems (now defunct). The system has a 1/2 barrel capacity* and utilizes a HERMS** heat exchanger in the hot liquor tank. Mash liquor is circulated by a pump from the mash tun through a heat exchanger or through a bypass. The heat stored in the hot liquor tank then acts as a heat reserve for the mash tun, allowing a constant temperature to be maintained in the mash or to allow heat increases in the mash for step mashes. A food grade pump circulates the mash liquor through the HERMS during the entire mash process.
After mashing is complete, the pump is then used to pump the wort over into the boiling kettle. The recirculation in the mash is stopped after the liquor runs clear. The ball valve on the mash tun is closed and the ball valve in the c-pcv manifold is opened. The sparge is begun and the boil kettle fills while heat is being applied to speed it to boil.
During the boil, a refractometer is used to determine and adjust the opening gravity of the wort. We've found that gravity adjustments during the boil are much less risky for infection and much more convenient than adjusting gravity in the carboy. After the boil a counter flow heat exchanger is used to cool the wort.
* 1/2 barrel = 15 gallons (approx.) ** HERMS = heat exchanger recirculation mash system