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High Gravity HERMS system
High Gravity HERMS system

How viable is Electric Brewing? HERMS

This series of articles takes a look at brewing with electric as opposed to propane and was sparked off (excuse the pun) by the winter of 2013 which due to the Arctic Vortex prevented me from brewing outside in the garage using my 3-tier Sanke keg-based system. The key problem was the lack of water due to frozen faucets (taps) and garden hoses.

False Bottom for a Mash Tun
False Bottom for a Mash Tun

In Part 1 of this series we examined the requirements which to summarize are as follows:

  • Ability to brew throughout the winter.
  • Ease of cleaning.
  • Worthwhile batch sizes.
  • Control of brewing process.

The potential options to be investigated include:

  • BIAB – Brew In A Bag.
  • HERMS – Heat Exchange Recirculating Mash System.
  • RIMS – Recirculating Infusion Mash System.
  • Conversion – upgrade, modify or convet my existing homebrew system.

We took a look at BIAB and some of the turnkey solutions available that are based on this approach. In this article we are going to examine HERMS…


Transfering Strike Water from the HLT to Mash Tun in a HERMS configuration
Transfering Strike Water from the HLT to Mash Tun in a HERMS configuration*

In order to control fermentability of the wort as well as the type of body desired within a beer (e.g. full body for a stout, medium body for an English ale, or light body for a lager), temperature control in the mash is essential. Even with a well insulated Mash Tun it is not uncommon to lose a few degrees of temperature over the hour or so. Also hot spots within the mash bed can occur and although stirring helps reduce these they do have the side effect of increasing temperature loss.

Two common ways of addressing the temperature loss are:

  1. Add more hot water to the mash but the problem with this is that the mash is diluted which impacts enzymatic activity and can affect the conversion of starches into sugars.
  2. Add heat to the Mash Tun but in the case of using gas this creates hot spots and can cause temperature fluctuations due to the heat going into the Mash Tun vessel itself which continues to be released after the burner is turned off. Use of an electric heating element within the Mash Tun would also create a hot spot with the element itself retaining heat even after being turned off.
Mash Recirculation with the Mash Tun in a HERMS configuration
Mash Recirculation with the Mash Tun in a HERMS configuration*

A way of addressing the above issues is through HERMS- or RIMS-based brewing systems which recirculate the wort and raise its temperature outside of the mash bed avoiding dilution of the mash and also because the recirculated wort diffuses through the mash bed it helps alleviate the issue of hot spots.

RIMS will be covered in the next article in this series but the basis of HERMS, according to an article in Brew Your Own, is the use of hot water as the heat source that usually incorporates a copper coil as a heat exchanger. The coil is placed in the HLT (Hot Liquor Tank) and used to heat hot water for sparging the mash. The water in the HLT is typically held at around 180 deg F (82 deg C).

AdvantagesThe key advantage of HERMS-based systems is the lack of scorching risk due to water doing the heating up of the sweet liquid in the mash as it circulates through the coil within the HLT. Also there is no direct heating of the Mash Tun. The complication of this system comes when the Mash is at the right temperature which usually means diverting the circulating sweet liquid through a loop to by-pass the coil in the HLT.

DisadvantageOne key problem that can be encountered with both HERMS- and RIMS-based systems is compacting the mash due to sucking the liquid out of the Mash Tun using a pump, this can be mitigated by using a false bottom or braided manifold. Another solution is to use a Lauter Grant that is gravity filled and then the sweet liquid is pumped out of this vessel.

Sparging from Mash Tun to Boil Kettle in a HERMS configuration
Sparging from Mash Tun to Boil Kettle in a HERMS configuration*

A one gallon grant is suitable for 10-15 gallon batch sizes but does need sensors for minimum and maximum levels to switch the pump Off and On accordingly. This is to ensure that the pump does not run dry.

Another article that provides a good introduction to HERMS and RIMS can be found on the Brewer’s Friend web site.

* HERMS diagrams are courtesy of High Gravity Homebrewing & Winemaking Supplies.

High Gravity provide a facility for a homebrewer to build a HERMS-based brewing system on their website. This includes are variety of options:

  • Stand – High Gravity recommend the Blichmann Top Tier Brew Stand with optional Pump Mounting Bracket and Utility Shelf.
  • Controller – to control the temperature of the HLT and Mash Tun as well as the Pump(s).
  • Power Plug Type – can be 3 or 4 prong.
  • EBC Configuration – for the ability of the Electric Brewery Controller to support a second Pump and also the length of power cord.
  • HLT – this varies in size from 11 to 55 gallons.
  • HLT Options – this includes a Heat Exchanger, the Heating Element (5500w), Boil Coil (240v and varies depending on size of HLT). There are also options to upgrade the Ball Valve and type of hoses.
  • HERMS Package – comprised of a Chugger pump, pre-assembled Input Manifold for the top of the Mash Tun, connectors, hoses and tie fittings.
  • Mash Tun – this varies from 13 to 55 gallons with the increased size being due to the need to hold the grain as well as liquid.
  • Mash Tun Options – AutoSparge to govern the flow rate of liquid entering the top of the Mash Tun over the grain bed.
  • Brew Kettle – this varies in size from 11 to 55 gallons.
  • Brew Kettle Options – this includes a Hop Blocker to stop hops from blocking the output of the kettle when the boil is complete. There are also Thermometer options as well as Heating Element (4500w or 5500w), Boil Coil (240v and varies depending on size of Brew Kettle), ability to upgrade the Ball Valve.
  • Plate Chiller – these include the Shirron and Terminator Wort Chillers plus connectors and Mounting Bracket (Therminator only).
  • Pumps – ability to add a second Chugger pump with disconnects and fittings.

Assuming you already have a Brew Stand, or can build one, the default price for a basic HERMS system from High Gravity Homebrewing & Winemaking Supplies is around $2450 (for a 10 gallon batch version) and can vary a lot depending on the options selected.

High Gravity HERMS system
High Gravity HERMS system

To brew with a HERMS-based system such as this one first of all the HLT is brought up to temperature so the Mash Tun can be filled with the strike water at a ratio of 1 gallon per 3 Lbs of grain e.g. 6 gallons for 18 Lbs of grain. The Strike Temperature of the water in the Mash Tun is then set to 10 deg F above the temperature that mashing is going to be carried out at.

Once doe-in is complete i.e. the grain has been added to the Strike Water and stirred the valve on the Mash Tun is opened and recirculation begins. After mashing is complete mash-out can then begin at 168 deg F so the controller needs adjusting to increase the desired mash temperature.

Once mash-out is complete the valve on the Mash Tun is closed so that the output hose can be moved over to the valve at the bottom of the Brew Kettle. Both valves on the Mash Tun and the Boil Kettle are then opened as well as the one on the HLT so the sparging can begin.

High-Gravity EBC III with temperature probes
High-Gravity EBC III with temperature probes

The flow rate of water into the Mash Tun is governed by the AutoSparge so that the grain bed retains two inches of water on top of it to ensure that it does not compact and also so that the Mash Tun does not overflow. As an added benefit running the sparge water through the HERMS system also cleans out the pump and heat exchanger.

Once the heating element in the Boil Kettle is immersed then the power from the HLT can be unplugged and the Boil Kettle can be plugged in and controlled from the same panel. The evaporation rate in the Boil kettle should be about 10% per hour.

Hop additions are now made to the boil at the regular intervals as per a normal brewing session and then once complete the wort is cooled.

A video of the EBC III Electric Brewery in Action can be found here.

Whilst looking at HERMS systems that can be purchased through retail the above one by High Gravity was the only electric-based one which could be found. The other systems all tended to be self-build and included the following:

  • E-HERMS Brewing System – watch the video here, there is no indication of the cost of building this system but the video is very educational.
  • The Electric Brewery – this web site (click here) contains a PDF guide on how to build an electric brewery ($19.95) which goes into a lot of detail and would be well-worth checking out, a forum, FAQ’s, information, and products available for sale which vary from individual parts and kits to pre-assembled modules. The estimated cost of building this brewery is $5991 to $6796 (+taxes & shipping) based on early 2014 prices. Prices will vary due to options chosen during the build and the kettles used based on desired batch sizes.

If you have any questions, suggestions, or comments on this article I’d really like to hear your thoughts to help with the decision on which system to go for!

Whilst a HERMS system has many advantages over BIAB systems as far as flexibility goes the key downsides are the high cost and cleaning of multiple brewing vessels so in Part 3 of this series we will be examining RIMS-based systems…

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