There are two popular brewing systems used by homebrewers and craft brewers alike: RIMS (Recirculating Infusion Mash System) and HERMS (Heat Exchange Recirculating Mash System). While both systems aim to achieve similar results – controlling the temperature during the mashing process – they differ in the way they achieve this.
RIMS systems operate by running the pump continuously and varying the heat source. This means that hot water or steam is continuously recirculated through the mash, providing heat to maintain the desired temperature. The temperature is controlled by adjusting the heat input, either manually or using an automated controller. This constant circulation of liquid helps to ensure even heat distribution throughout the mash, reducing the risk of temperature fluctuations.
On the other hand, HERMS systems turn the pump on and off to control the temperature, drawing heat from a fixed source such as the Hot Liquor Tank (HLT). In a HERMS setup, a coil or heat exchanger is placed inside the HLT, through which the mash is circulated. The HLT is heated independently, and the hot water or liquid inside the HLT is used to heat the mash as it passes through the coil. The pump is activated periodically to recirculate the mash and maintain the desired temperature.
The main difference between RIMS and HERMS lies in the heat source. RIMS systems have the advantage of being able to vary the heat source, which gives brewers more control over the heating process. This flexibility allows for precise temperature adjustments during the mash. However, it also means that the heat source needs to be monitored closely to prevent overheating.
HERMS systems, on the other hand, rely on a fixed heat source (usually the HLT) to heat the mash. This can provide more stable and consistent heating, as the temperature of the HLT is typically easier to control. However, it may require more time for the heat to transfer from the HLT to the mash via the heat exchanger, resulting in slower temperature changes.
In terms of practical implications, RIMS systems may be more suitable for brewers who prefer to have more control over the heating process and are comfortable with monitoring and adjusting the heat source. On the other hand, HERMS systems may be preferred by brewers who value stability and consistency in temperature control, even if it means sacrificing some flexibility.
Both RIMS and HERMS systems have their advantages and disadvantages, and the choice between the two ultimately depends on the brewer's preferences and brewing goals. Some brewers even combine the two systems, using a RIMS setup for temperature control during the mash and a HERMS setup for maintaining temperature during the sparge.
Personally, I have used both RIMS and HERMS systems in my brewing journey. I found that the RIMS system allowed for more precise temperature control, especially when experimenting with different mash profiles and recipes. However, I also appreciated the simplicity and reliability of the HERMS system, particularly when brewing larger batches where maintaining consistent temperatures is crucial.
While RIMS and HERMS systems differ in their approach to temperature control during the mashing process, both can be effective tools in a brewer's arsenal. Ultimately, the choice between the two comes down to personal preference and the specific brewing requirements of each individual.