JTs Beer Equipment Page


Or Heat Exchange Recirculation Mash System.


If you have a pump then you want some way to maintain or raise the

temperatures of your mash.

How a HERMS works

A coil of tubing is placed into a vessel with water that is heated.

The hot water transfers the heat from the water through the tubing

to the wort as it is pumped through the tubing.

Important points about using a HERMS

The manifold must not cause the mash to compact and reduce flow.

You need a flow to transfer the heat from the coil to the wort.

Your return must not splash or cause tunneling through the mash.

Construction of a HERMS


A HERMS coil can be made more ways that you could imagne.

I made mine from a 20 coil of OD copper tubing with copper

pipe risers. The finished it off with fittings to adapt it to a hose thread.

Most brewers put bulkhead fittings into their HLT. I wanted the ease

of cleaning so I opted to bring mine out the top of the HLT. In use I

simply place the coil in my HLT and connect the inny and outy hoses.




The Return Manifold


I constructed my return manifold from CPVC.

I just pushed all the parts together without glue. This way

it is easier to take apart and clean. I drilled some 1/8 holes

in the top of the manifold. I use a zip tie to set the depth of

the manifold so its just even with the top of the water. This

way the return flow gently mixes back into the mash.





HLT = Hot Liquer Tank a place to heat water for your mash

Wort = Unfermented Beer






Using a HERMS

A typical session for me is to dough in a few degrees low and with the HLT

10 - 20F warmer than my desired mash temperature I switch on the pump.

When my desired temperature is reached I simply switch off the pump. While

there is some wort in the tubing that will be higher than the desired mash temperature

it will be minimal. If you hook up your plumbing the way I do you can flush the

coil after each use.