HERMS Brew Station

At the moment I decided to build HERMS I got two kegs and plastic bucket. I decided to use bucket for HLT only temporary, but with time it turned out as cheap and functional solution, it is made from HDPE(High-density polyethylene) which can withstand higher temperatures (120 C/ 248 F for short periods, 110 C /230 F continuously).

HERMS works as circulation system: sparge water is heated with 2 x 2kW heaters in HLT which are controlled by PID. Sparge water also maintain mash temperature since wort circulates trough HEX coil in HLT during the mash. After positive iodine test (mashing is over), 1st wort is circulated to BK and sparge water (from HLT) is added to MLT for sparge (I am batch sparger). Then I fire up BK and add FWH if recipe requires so. Sparge water is mixed with grains in MLT, poured to BK and that is it, rest of process is same as in other setups.

This is scheme of all joins on kettles:


Both kegs had different system, D and S system, here is short instruction how to open them:Turn the keg sideway and release pressure first (use screwdriver or similar tool), you don’t want beer shower in you face.D-System1. Use screwdriver to release inner ring2. With hammer and screwdriver punch lug on inner side of valve (clockwise)3. Screw the valve until it stops, then with your thumbs raise the valveS-SystemThis is somewhat complicated than D-system (but not too much)…1. With hammer and screwdriver punch the inner ring (counter clockwise)2. When bung releases you’ll be able to screw it to end, but on this system there is safety catch that is protecting valve from blowing the valve3. Safety catch is located under the lug with stamped “S” on it. Use piece of metal pipe (or something similar) to press the rubber seal in the top of the valve4. When pipe is blocking the valve, use screwdriver to press the safety catch (you’ll be able to see it under the valve).Since picture is worth a thousand words, here is one that should clear things out:


You don’t need plasma cutter to cut the lid (although it would be nice if you have one on the hand). This is my “cut keg” jig, modified version of our member dutchoven:

I used keg tap to center wooden construction with threaded rod:

and it was ready to start

Cuts were pretty clean, I used brush to clean sharp spots on edge:

Remember to fill the keg with water (just to cover the bottom) to prevent sparks from sticking to the bottom.


Since I used HDPE bucket all joints are weldless, you can use step-drill-bit to cut holes for:

– HEX (Heat Exchange) coil
– Input and output ball valves
– Heater elements
– Temperature probe

Weldless connection detail:

First you have to re-coil copper coil to right diameter, to do that simply tighten the coil around keg or some other vessel. I used 17 feet copper coil (OD 12 mm), and after re-coiling I mounted ball valves on HEX coil outside. Now you can mount input and output ball valves, temperature probe and heaters.

I used 2 x 2kW heaters and they are doing great job for my 50L HLT. Use this calculator to calculate how much time will be needed to heat certain volume to desired temperature:

For temperature probe you can use RTD or K-type probe, I choosed RTD because of its better accuracy.

Finished HLT:

As you can see, I added sight glass directly on output valve. To do so, simply attach T-connection on output nipple and mount compression fitting on upper side and ball valve on other side of it.


Control panel holds PID, temperature displays and switches for PID, displays, heaters and pumps.
You don’t have to install separate switches for heater elements since PID will control them, I though that I would fire them separately but in practice I never do that.

I made dis-connectable temperature probes using 3-pin XLR connectors that are used in audio/video electronic applications. You can easily solder 3-pin cable from RTD probe to XLR connector so you can dismount probe from control panel.

Wire diagram:


Mash tun has input quick connect and output valve with quick connect. To install valve and input connect you can either solder them or use weldless join as described above. At first, I installed RTD probe on MLT,but since 4″ probe comes half way to center of keg and it makes stirring pretty difficult I decided to take it off and make simple T-connection temperature probe (thanks to Lonnie McAllister for idea) and measure income wort temperature. For mash temperature I simply insert glass thermometer into mash, and according to that I adjust PID temperature.
One another reason why you don’t need probe in you MLT is that temperature of mash will be mostly constant during mashing (assuming all other factors are constant: outside temperature, flow, pipe line length).

Inside of MLT:

T-connection temperature probe:


I used keg lid to make false bottom, and after almost a year i can say that it is working really good, I am able to crush the grains (wet conditioned) pretty tight (0,032″) and still don’t have problems with sparging.With angle grinder I made slots 0.08″ wide, which makes 15% open area.

I used part of keg valve with some copper reducers to seal center for dip tube.

This is how it looks before soldering:

and after:


Boil kettle have input quick connect and output valve with quick connect, and building it is same as it is for MLT. One exception is that input is located at the middle of keg, reason for this is because you don’t want your first running wort to splash from top of keg, and also whirlpool is stronger if wort is returning to BK nearer bottom. Boil kettle also have sight glass mounted on output valve on the same way it is on HLT. Dip tube is made from copper pipe and compression fitting, is is positioned to the side of keg so it doesn’t pick trub cone when transferring wort to fermenter. Boil kettle dead space is 0.4 gallons.Boil kettle with hop stopper:

Position of input and dip tube in BK:


This is simple wooden brewstand with the exception of CFC mounted under boil kettle. I made it from 1.5×2″ lumber, 1×4″ lumber and 19mm thick MDF board.Construction is pretty simple, screw 1.5×2″ and 1×4″ decks and mount MDF boards on top:

RTD probe mounted on outside of CFC:

Finished system. It’s time to brew!


28 Responses to “HERMS Brew Station”

  1. Brew_Junkie on

    You have to be an engineer by profession. Everything is so exact and “perfect”. I have just tested my RIMs system, and it looks undone at this point. It does work, however.

    I will try to pretty it up like you have done. Great post, thanks.

  2. diS on

    Yup, I am an engineer, but forest engineer not machine :)
    This is not that complicated as it maybe looks, just be pedantic and orderly.. but there is thin line between perfection and obsession.. :)

  3. frescodesigns on

    this is truly a thing of beauty! i will have to convince my engineer BF to make something like this for me! thanks for sharing :)

  4. frankieboy007 on

    For the HLT, are the elements 110 or 220?? I’ve already got my HERMS rig mostly set up, and have been thinking of doing electric for the hot water and sparge, which would be extremely handy, not to mention a gas saver. Also, how did you get your kegs so shiny? Great rig, and great post for the DIY guys!!

  5. diS on

    Elements are 220V.
    Kegs are polished but I made a mistake and abraded it with sandpaper (drill mounted) first. It is great to cover scratches but don’t scrap the rest of keg.

    It could be even shiner but I don’t want fingerprints to clean :)

  6. diS on

    After 1.5 year system is working nice, there is a lot of great brews under its belt.. at the moment I am thinking to replace plastic HLT with SS one, plastic and copper are great/cheap to start with but after a while they become boring.

  7. diS on

    I did it myself, actually two of them: this one and one that is narrower in diameter.
    It is not complicated to build, use SS mesh screen, some SS round frame (like frame from sieve cake), few SS rivets and that is all you need.

  8. cb2100 on

    That is fantastic brother, good work! I’m getting inspired… The fact you made it so easy to follow cements my decision to make something like this. Thanks!

  9. Scubasteve1782 on

    Great post! Awesome setup. What are you using for the kettle lids? Look like simple kitchen pot lids.

    Also, this maybe an amateur question but how are you drawing off the remaining 0.4 gallons of wort post boil from the dead space?

  10. diS on

    Yes, lids are from kitchen pots, they match perfectly.. just keep in mind diameter of lids when curring keg top.
    I leave about quart and half in BK , that is mostly hot/cold breaks, hops residues etc.

  11. Aaronhamann on

    Does a HERMS increase efficiency? If so what kind of numbers do you get? Also, do you do a mashout and just batch sparge with the water in the HLT? Or is it batch sparged through the HERMS coil? Thanks in advance.

  12. diS on

    In my case HERMS doesn’t effect efficiency but it makes process constant. Numbers I usually get is between 77 and 80% but I don’t think HERMS is the main reason, grain mill and false bottom are more important IMO.
    I batch sparge every time, but occasionally I do a mashout (when I remember to increase temperature), sparge water runs trough HERMS coil (since there is some wort left there after mashing). Hope it helps.

  13. TedandMargeBrewing on

    Great build! Lots of idea floating around in my head now.. One question though, where did you get your temp probe from and how much? I really like the idea of having a QD on my probes.


Leave a Reply

  • (will not be published)