Recirculating mash systems
Recirculating mash systems are brewing systems that incorporate a recirculating pump to maintain a stable temperature during a mash. The most common recirculating mash systems are RIMS and HERMS systems.
Recirculating mash systems generally
No matter what acronym is used to describe them, all recirculating mash systems work in essentially the same way. A portion of the wort is forced out of the mash tun using a pump, heated, and then returned to the mash tun.
These systems have three main benefits:
- The constant recirculation gives a much cleaner wort during lautering than a manual vorlauf
- The temperature can be held more constant than using other heating methods
- The process as a whole results in a more consistently repeatable mash
Types and components of recirculating mash systems
RIMS stands for Recirculation Infusion Mash System. This refers to a recirculating mash system in which the recirculated wort is passed over direct heat. The direct heat may be applied by an electric heating element suspended in a tube after the pump. It may also be applied via direct heat under a metal mash tun (this would be called a direct fired RIMS to distinguish it from the previously mentioned version). In just about all RIMS systems, the pump operates constantly during the mash, and the heat (flame or electric) is cycled off and on to maintain the desired mash temperature. While the cycling of the heating element can be controlled manually (physically turning the element on/off), most homebrewing RIMS systems use an electronic PID temperature controller to control the cycling of the heating element. Common heating elements used in home-built RIMS systems are home hot water heater elements encased in a copper pipe with an inlet and outlet.
The most well known RIMS system (direct fired) around is the BRUTUS 10 which you can see at .
HERMS stands for Heat Exchanged Recirculating Mash System. In a HERMS system, the wort is passed through the heat exchanger, usually a copper manifold, that is suspended in hot liquid. Usually the hot liquor tank is used for convenience since water will be used for sparge afterwards. The most accurate and preferred method of mash temp control is inserting the temperature controller's sensor inline with the wort at the exit of the heat exchanger. The controller will then cycle HLT heating on and off to keep the wort returning to the mash tun at your setpoint.
Examples of home-built HERMS systems
In some recirculations, the wort is fed by gravity to a separate vessel below the mash tun, called a grant. This means that no suction is exerted on the mash tun itself, avoiding the possibility of suction compacting the grain bed.