The Mash Tun - 5 gal. Electric Brewery

I started planning / building a home brewery about a year ago. The concept was simple enough, I wanted a brewery that would allow me to make a 5-10 gallon batch of beer in my garage, with good repeatability. After a lot of research, I decided to go with electric elements, since they met my criteria, and would allow for a bit more flexibility in the future.

For temp control, I was tempted to go with one of the off the shelf PID controllers out there, however, I had a microcontroller development platform (Parallax BOE) that I purchased when I was in school, in a box in the garage and I though "this would be a great time to put that thing to use". The temperature monitoring is done using 3 LM34 transducers, and a MCP3204 ADC. The temperature control is done using 2x 240V - 40A SSR's that power The immersion elements. There are a few push buttons and an LCD display with a menu system for selecting the operating mode and adjusting setpoints / duty cycles. The Parallax board, temperature sensors, and LCD, get their power through a Lambda 9V supply that is connected to the main power.

When the unit is powered up, a menu is presented on the display. The modes available are: Mash - Boil - Chill. When a mode is selected, an initial screen displays the user entered parameter, along with a pre programmed value. At this point, the increment / decrement buttons will change the value, and upon pressing enter, the controller begins trying to reach the desired temperature. The display shows the set point, the actual temperature, and the duty cycle that it's running at. During operation in this mode, pressing escape will take you back to the initial setting screen so you can adjust the setting, and pressing escape one more time will take you back to the main menu so you can change modes. The Chill mode simply displays one of the temperature readings in big number mode on the 4x20 display. During this stage the temperature being monitored is the outlet of a heat exchanger that I am using to chill the wort.

All of the vessels are made from 50l kegs. I used a friends plasma cutter to take the tops out, and had another friend weld in the fittings for me. I considered weldless, but said friend happily works for beer, and I have a thing for pretty little TIG welds. The HLT and Kettle have 5500W 240V elements for heating. I got a few scraps of wedge wire from a local micro brewery, and made them into a very nice false bottom. I am using the HopStopper in the kettle as an outlet screen.

The brewery is plumbed to make use of the counter flow heat exchanger for both heating and cooling the wort. The HE is used for heating during the mash portion of the brew. During heating, water from the HLT is pumped through the outside of the HE, returning to the top of the HLT. While this is happening, wort is pumped through the inside coil of the HE and returning to the top of the Mash Tun. The circulation of water from and to the HLT will be enough agitation to eliminate stratification of the HLT. Recirculating the wort through the HE causes the grain bed to act as a filter, and catch most of the husks and fine material that washes through the false bottom. During cooling, the wort is pumped through the inside of the HE, and into the fermenter. Tap water runs through the outer pipe, and on exit is dumped into the HLT to be used as clean up water. Connections to the HLT are hard piped, as they never need to change, and the only thing in the HLT will be clean water.

The heat exchanger is made up of an outer shell of 1/2" copper pipe (5/8" O.D. - 0.527" I.D.) and an inner tube of 3/8" copper tube (3/8" O.D. - 0.311" I.D.). The coil is 10' long in total. The calculations I have done show that with 55 degree tap water, and 210 degree wort, flowing 6 gallons of each through the exchanger over 10 minutes should result in wort at 67 degrees and water at 195 degrees. I am interested to see how the real thing works out. I may need to flow more cooling water, and run the wort through a bit slower, which is not a problem - it just gives more washing up water. If the ground water is too warm, I am able to fill the HLT with water and ice, and using the same plumbing route as during the mash, circulate ice water through the shell side of the exchanger.

I am using 2 Chugger S/S pumps to circulate the wort / water. They have been working very well during testing.

I finished the build last weekend, and have been messing with the microcontroller and temperature control regime since. I haven't brewed yet, but I have run through the process a few times using just water. I still have some bugs to sort out, but at this point, brewing is doable. I'm sure I've missed some things in this whirlwind description, but between this and the pictures, I'm sure it gets the point across.

The following pictures are pretty self explanatory. There are a couple shots of the false bottom, one with it on the floor, hinged up, and the other in the mash tun.
The schematic shows the connections and valve schedule for each step of the process.

These pictures show the plumbing in it's finished state, and a couple shots of the complete system during testing. It's a pretty good feeling to finally get here after all the time in development/build. I am excited to start brewing on it.

Cool!

Very nice. Thanks for the sharing. Gives me some ideas for my build.

Excellent!

We're not worthy! We're not worthy!

Nicely done indeed!

Very nice.

Thanks Guys, It's a great feeling to have things pumping around and steaming away. I wanted to see what the heat exchange was capable of, so I did a "Mash Tun Shoot out". I got the HLT to boiling, with cold water in the mash tun, then I flipped the pumps on and waited to see what the mash temp stabilized at. It got up to 180 degrees surprisingly quick, then took a while to get to 190. If I'd given it another 20 minutes I probably could get another 5 degrees, but I was happy at 190. I think that using this approach, I could do decent step mashes, cranking the HLT, and using the exchanger flow to control the temps.

Very nice work Russ! I'm guessing you like to understate things calling your work a "5" gallon brewery. Ilike the dark stain on the wood as well.

Nice work--love the panel. Your friend is a good welder too.

Wedge Wire huh? Learn something new every day on this board.

Is that OJ Simpson and that girl who was on trial for her daughters murder recently? That's nuts if it is

RussH said:

The brewery is plumbed to make use of the counter flow heat exchanger for both heating and cooling the wort. The HE is used for heating during the mash portion of the brew. During heating, water from the HLT is pumped through the outside of the HE, returning to the top of the HLT. While this is happening, wort is pumped through the inside coil of the HE and returning to the top of the Mash Tun. The circulation of water from and to the HLT will be enough agitation to eliminate stratification of the HLT. Recirculating the wort through the HE causes the grain bed to act as a filter, and catch most of the husks and fine material that washes through the false bottom. During cooling, the wort is pumped through the inside of the HE, and into the fermenter. Tap water runs through the outer pipe, and on exit is dumped into the HLT to be used as clean up water. Connections to the HLT are hard piped, as they never need to change, and the only thing in the HLT will be clean water.

Click to expand...

I really like the idea of minimizing HLT modification by moving the HERMS coil to an existing counterflow chiller. Has it so far met your expectations and is it maintaining the temperature you'd like it to? Any surprises?

I'm curious how you perform temperature control during this process. You're recirculating HLT water and MLT water through the HEX, but temperature can only be changed through adjustment of the HLT heating element. Does your controller monitor MLT, HLT, or the MLT return from the HEX to adjust the HLT element? Or do you simply set the controller to maintain HLT temps and throttle the valves to maintain MLT temps?

I've been considering using my Therminator plate chiller in a similar fashion.

Though not sure how effective it would be compared to a single coil (like an immersion chiller) sitting in a large pot of heated water.

I really like the idea of minimizing HLT modification by moving the HERMS coil to an existing counterflow chiller. Has it so far met your expectations and is it maintaining the temperature you'd like it to? Any surprises?

I'm curious how you perform temperature control during this process. You're recirculating HLT water and MLT water through the HEX, but temperature can only be changed through adjustment of the HLT heating element. Does your controller monitor MLT, HLT, or the MLT return from the HEX to adjust the HLT element? Or do you simply set the controller to maintain HLT temps and throttle the valves to maintain MLT temps?

Click to expand...

That was my thinking also, I knew I was going to have 2 pumps, and a counterflow exchanger, so why not use them as much as possible. So far it's performed very well. The heat exchanger works very well, and I really like the way I have it plumbed, it makes for a fairly straight forward process.

I am still "refining" the temperature control plan. For a single temp mash, the method is to set the HLT, fully open the water side valves, then open the wort side outlet enough to get a good flow without collapsing the bed. The HLT temp needs to be 5 or so degrees higher than the desired mash temp, just to allow for cooling in the lines. I do monitor the temp of the wort as it leaves the heat exchanger, and I am going to play around with using this temp to drive the control. I suspect that in doing this there will be such a lag between action and reaction that it may 'confuse' the program and result in instability. For now, putting in the 5 degree correction isn't a big deal.

I am also experimenting with step mashes. My plan there is to turn off the wort side pump for a few minutes while I bump the HLT temp up, then when I turn the pump back on the mash temp will rise quickly to the same temp as the HLT.

Though not sure how effective it would be compared to a single coil (like an immersion chiller) sitting in a large pot of heated water.

Click to expand...

With counterflow, you get a much more effective heat transfer, since both sides of the fluid are moving. The biggest factor in heat transfer between a fluid and a surface (say the inside/outside of a pipe) is a thing called the film coefficient. The more turbulent the flow, the higher the film coefficient. So if the fluid on both sides of the pipe are turbulent, you get a very effective transfer, and can get away with a much shorter coil (that's why the convoluted tube exchangers work so well). In a large pot of water, the fluid on the outside is going to be virtually still, even with some form of stirring contraption in the HLT, the fluid will never be anywhere close to turbulent.

In general, both ways of doing it have their ups and downs. They'll both work, and each one is going to have an application where it works better than the other. It really comes down to preference, and what you're comfortable with. I built my own heat exchanger, and I did quite a bit of calculation to arrive at the final design, so I wanted to make the most of it.

Looks awesome. Do you have plans for the controller available?

RussH said:

I am still "refining" the temperature control plan. For a single temp mash, the method is to set the HLT, fully open the water side valves, then open the wort side outlet enough to get a good flow without collapsing the bed. The HLT temp needs to be 5 or so degrees higher than the desired mash temp, just to allow for cooling in the lines. I do monitor the temp of the wort as it leaves the heat exchanger, and I am going to play around with using this temp to drive the control. I suspect that in doing this there will be such a lag between action and reaction that it may 'confuse' the program and result in instability. For now, putting in the 5 degree correction isn't a big deal.

Click to expand...

Sounds great. Please keep us up to date on how this all works out!

Brewed my first batch today, went very well. Boiled off way too much and had to add a bunch of water to get the gravity right. Did a fat tire clone, after the boil it was at 1.062, added water to get 1.055. Here are a few pics.

Fantastic! Looks like you've got a great rolling boil. What is the tube coming down the side int he last picture?

Out curiosity, where did you get your fittings and boil screen from? I'm getting my tiered setup planned out right now. Nice setup by the way, it's good to see some more island representation here

vfinch, right on. I got my fittings from bargain fittings, and used Seawings to bring it to canada. Screen is the Hop Stopper from IHS. Works well from what I can tell, the siphon breaks really easy though when you're pullin through the trub. How far along are you?

wyoder, That is the pump outlet hose from the mash tun, I was pulling off for the boil when that picture was taken.

RussH said:

vfinch, right on. I got my fittings from bargain fittings, and used Seawings to bring it to canada. Screen is the Hop Stopper from IHS. Works well from what I can tell, the siphon breaks really easy though when you're pullin through the trub. How far along are you?

Click to expand...

Cool, just wondering how the process was. I'm still in the process of designing it right now, but it's going to be electric with an external HERMS. Some of the bits I'll be sourcing through work, but the fittings are an unknown right now. We have a US drop point in Blaine WA that I will probably use again (we get and receive a lot of US shipments).

DAMN!! Amazing stuff man

kellzey said:

Excellent!

We're not worthy! We're not worthy!

Click to expand...

What HE said!!