Intro to RIMS and HERMS Homebrewing

If you’ve seen the terms “HERMS” and “RIMS” being tossed around in the brewing world, you may feel like you are in over your head and have no clue what everyone is talking about.  In reality, it is a fairly simple concept that aims to result in more consistent, less-stressful brew days.

Over the next few weeks, I will walk you through my HERMS (Heat Element Recirculating Mash System…we’ll get to that) build, but first, I wanted to write a post explaining the concept behind the HERMS and the RIMS (Recirculating Infusion Mash System).

How Does RIMS Work?

A RIMS is a recirculating infusion mash system.  Well yes…and what is that?  It is a simple concept where during the mash, where we typically allow the grain to soak in warm water for about an hour, the wort is recirculated using a pump.  OK, that makes sense, but what is the advantage of this?  The advantage comes when you recirculate through a tube that has a heating element installed that can heat the wort as it passes by; or just recirculate past a temperature probe that will measure the temperature, which tells you (or a control panel if you’re fancy) when to add heat to the mash tun via a burner or an electric heating element.  This allows you to hold the mash at a very precise temperature over the course of the hour-long mash.  No more worrying if your mash temperature is going to drop too low during the cold winter months.

RIMS diagramThe reason you do this is because the fermentability of the beer is greatly impacted by the mash temperature.  If you mash at 148-degrees, then you end up with a highly fermentable beer that will come out very dry with a low final specific gravity.  If you mash at 155, then you have more non-fermentable sugars which will result in a more full-bodied beer with a higher final specific gravity.  By using a recirculating system to control the temperature, you can make sure that your mash temperature is spot on every time.  This will result in more consistency from batch to batch and allow for more granular changes in mash temperature.

How Does HERMS Work?

A HERMS is a type of RIMS.  The Heat Exchanging Recirculating Mash System does all of the same things that a RIMS does, except that there is no direct heating of the wort by passing it over a heating element or direct firing of the mash tun with a gas burner or a heat element.

Instead, HERMS will circulate the wort from the mash through a copper coil that is located inside of your hot liquor tun (HLT).  The temperature of the water in the HLT is adjusted using a heating element or a gas burner.  This way, the heat of the HLT water is transferred to the wort via the copper coil.  This is where the name “heat exchanging” comes in.

HERMS diagramIt is a much more gentle heat exchange in comparison to the direct heating of a standard RIMS.  Because the wort itself is not directly heated, you lower the risk of scorching it.  HERMS has also proven to provide slightly better control of the wort temperature.

herms coilI have elected to upgrade my current 3-tier gravity system to an eHERMS (the little “e” means “electric”).  I will install a copper coil with a temperature probe inside my current HLT so that the wort can recirculate and I can measure the temperature of my mash.  I will also install an electric heating element into the HLT to control the heating of this water.  That way, I can have a control panel that will read the temperature of the recirculating mash and tell the electric heating element when to turn on or off.  Totally hands-off temperature control.

My pump, tubing, quick disconnects, and keg couplings all came in the mail today.  I have not yet ordered the electric element, temperature probe or control panel parts.  For the copper coil, I am going to use my old immersion chiller, since I have upgraded to using a counterflow chiller to cool the wort.

It should be a fun build!  I will post pictures along the way for everyone to follow along.

If you are interested in using the HERMS or RIMS methods, but don’t feel like you have the expertise to build a system yourself, you can purchase some pre-built systems for a little more money.  One of the most popular options is the Blichmann Tower of Power.