A Heat Exchange Re-circulating Mash System or HERMS for short is a multi-vessel brewing system that utilizes a heat exchanger submerged in the systems hot liquor tank (HLT) to maintain the mash temperature. The wort is moved via a pump from the bottom of mash tun through the submerged heat exchanger in the HLT. The wort gets heated as it passes and then is added back to the top of the mash. The temperature of the mash is controlled by turning the pump on and off. This function is performed by a temperature controller that cycles power to the pump based on the temperature of the mash and the controller’s set point.
Both HERMS and RIMS (Recirculating Infusion Mash System) are very similar in the fact that they use a pump to move the wort which gets heated while it’s outside of the mash. However in a RIMS system the pump is constantly moving the wort and the heating source cycles to control temperature. The heating source can be either electric or gas and it directly heats the pipe that the wort of flowing through. Whereas on a HERMS system the water in the HLT is heated and the wort passes through the heated water to maintain temperature.
Most all grain brewers already own a mash tun, pump, immersion chiller and temperature controller. That aside from the tubing is all you need to build a HERMS system, so they are relatively easy to build with parts you might already have on hand. Aside from parts the other benefit is you’re utilizing the energy used to heat your sparge water to maintain your mash. So you use less energy in the long run.
Below are some of our complete HERMS brewing systems as well as some parts needed to build your own HERMS setup. If you have any questions about HERMS please give us a call.