2 tier, 2 zone fermentation chamber build (AKA Racer X)

[Mtn_Brewer]

OK, time to post up. I got the idea for this build from Zacc's build:

https://www.homebrewtalk.com/f51/2-zone-fermentation-chamber-build-344775/

I've used a chest freezer and fan heater controlled with a Ranco temp controller for awhile. It works OK but I brew a lot of lagers and it was kind of a pain to have to coordinate all of my brews Having a fermenter with 2 zones was the obvious answer. I used Zacc's idea for the basic design and then came up with some innovations. I decided that I wanted everything to be as internalized as possible, including the heating and cooling elements. I also wanted it to be large enough that I wouldn't feel the need to upgrade in the forseeable future. I spent a lot of time designing it in a spiral notebook, who needs sketch-up? I configured it so that I can fit 6 carboys into each chamber and still be able to panel it with 4 x 8 sheets of plywood.

OK, so here's the build...

 

[de3isit]

Nice looking build.

Can you give some details on the changes you made to your design? Maybe some inside pics?

 

[Mtn_Brewer]

I first built the base from 3/4 inch plywood and a 2 x 4 frame. The top layer of plywood sticks out 2 inches on all sides. I insulted it with 3 1/2 inch batt insulation with an R value of 13. I built the sides and top in sections and then attached them. The dividing section was then added and insulted with some foam board insulation and batt insulation. The AC hole took some time to figure out. I wanted it to be at the right height to fit in next to my work bench and also to allow the AC unit to be removed and serviced/replaced if needed in the future.

 

[signpost]

That thing is awesome! :rockin: I'd still love to see some inside pics of the final product.

 

[Mtn_Brewer]

The cooling system for the top chamber uses a fan to drawn air from the lower (lager) chamber and spit it out on top. Zacc and other used pipes inside the chamber and computer fans but I wanted to internalize the circulation system. I worked out this pan to use the bathroom fan in the wall and built the ducts using PVC piping. The recirculation system on the opposite side spits the air out over the top of the AC unit. The PVC pipes were connected together and secured in place with epoxy and metalic duct tape. I paneled the inside with 1/2 inch plywood, trying to get as tight a fit as possible.

 

[Mtn_Brewer]

Once the inside structure was done and the venting was installed, I sealed the seams with some industrial strength caulking and painted it. For the heat sources, I spent a lot of time researching wall heater units. I decided on the Broan 120 heater. It can be rewired to 500 watts at 120volts in about 5 minutes by following the instructions. I found them on-line for $60 each. I installed them in the vertical position because the air intake is on the bottom and the output is on top. I mounted them high enough that they will not blow directly on the carboys. I used a sheet of flooring from Home Depot, that I glued directly to the plywood and then sealed with caulking and re-painted.

 

[Mtn_Brewer]

The control panel was built out of a steel junction box I got at the local recycling facility. I put painter's tape down to cover it and drew out the design. I cut the holes with a dremel tool, drill and file. I built an external fuse box using a metal outdoor outlet box. It is lockable to prevent curious kids from electrocuting themselves but allows fuse changes without having to remove the front panel.

 

[Mtn_Brewer]

I wired all the components to the side and insulated the whole thing in 3 1/2 inch batt insulation, trying to get as good a seal as possible with the vapor barrier. I closed it in with 1/2 inch plywood and then painted it with Behr Premium Plus Ultra, which is water based but extremtly durable and mildew resistant (if you believe the packaging). Before pulling through the wires, I put the control panel over the spot it would be and drilled the holes. Once the paint was dry, I pulled the wires through and secured the box with lag screws. I installed the buses and ground bar and got to work on the wiring.

 

[Mtn_Brewer]

I wired up the positive bus and then pulled the wires through to the fuse box. I used AGC fuse holders I got from the local electronics store. The AC, cooling fan and heaters are controlled with single pole contactors. Despite my best efforts, wiring got messy fast.

 

[Mtn_Brewer]

The control panel has 2 Auber 1/4 DIN PID's as the main controllers. The toggle switches next to the PID's power each one up individually and also the respective heater and cooling source. The heaters can be switched on or off individually by the middle switches, which interrupt the output to the coils on the relays. Although this isn't necessary, I figured there would be times when I would want to have the heaters off when I have the door open and it avoids having to go through several steps to turn it off on the PID. Interrupting the coil output seemed to be the easiest way to do this. For general air circulation in the chambers, I installed some door mountable fans from home depot. They have individual switches and are controlled by a cycle timer from Rammeter.com and a 1.5 amp fan controller. I also installed a fan controller to the upper chamber cooling fan to allow more fine tuning of the system. The covered switch on the left side of the panel is the main power switch. I covered the vents with 240 volt outlet plates and some heavy duty screen I got from home depot.

 

[Mtn_Brewer]

Technically, I think making the doors was the toughest part. When I paneled the front of the fermenter, I measured and marked the doors with meticulous detail. I cut them out using a circular saw carefully so I could use the inserts in the actual doors. I used 1 x 4's that I glued in place with some strong wood glue and then secured with short screws from behind. I hung the doors to get the right places for the screws and hinges and get the latches worked out. The 1 x 4's didn't leave enough of a gap for the weather stripping, so I attached a 1/4 x 4 inch board over the top of the hinge and latch blocks. This left just the right amount of gap for the weather stripping. I took them down and framed the back with 2 x 3's and insulated them with foam board. I think the R value is 7.5. Through trial and error, I figured out that I needed to cut the right side of the 2 x 3 framing at a 15 degree angle so it would close without hitting the door frame. I paneled it with 1/4 inch plywood then filled in all the gaps with wood filler. Once it was dry, I used an angle grinder to even up the plywood with the 2 x 3's and then painted them.

 

[Mtn_Brewer]

I sealed the doors with some weather stripping from home depot. I kept the two strips connected to get a double seal. I cut a 1/4 inch slice out of the inside strip to allow it to navigate the corners. I used 1/4 inch staples to secure the stripping. I had to use a hammer to flatten the female part of the latches (~1 mm) to get just the right seal.

 

[Mtn_Brewer]

I used K type thermocouples as sensors. I got them from Auber instruments. They are meant to be used in air inside kilns, so I just hung them from eye screws in the corners. In my chest freezer, I never submerged my probe or used a thrmowell, so I figured this would work for this chamber as well. I used a location where neither the heater or AC/cooling fan would blow directly on the probe.

 

[Mtn_Brewer]

I made a DIY chalk board for the front out of a piece of galvaized sheet metal I had left over from my hood build(https://www.homebrewtalk.com/f51/diy-garage-hood-heat-shield-375755/), a can of chalkboard spray paint and a 12 x 36 inch frame. This way I can easily keep track of fermentation schedules and gravity readings. As a finishing touch, I added the metal Racer X sign. For those of you not old enough to remember the old Speed Racer cartoons, I suggest you look it up on youtube.

 

[max384]

Wow. Excellent build! How cold can you get the chambers with that AC unit?

 

[Mtn_Brewer]

I almost forgot...a word about AC unit choice.

I bought an LG LW5012J AC unit from Home Depot for ~ $100. I knew I was going to have to do something to get down to lager temps, as the thermostat (like all AC units) would not cool below 50 degrees. I knew I couldn't do the trick of pulling the temp probe outside of the chamber, because my garage frequently is between 40-50 degrees, so I couldn't get to my usual lagering temps. I took apart the front of the unit, as shown, thinking I was going to have to find some way to bypass the thermostat. Fortunately, I discovered this screw on the side of thermostat that I figured out was the tuning screw. By turning it ~ 10 turns to the left, I completely turned off the temp governor. I sealed the unit into a small plastic container and found I could get the temp down to 10 degrees! I was therefore able to put the whole unit back together again without any DIY mucking around.

 

[chipsah]

Damn it. I am trying to keep the garage in my new house as a sleeping place for my Jeep. Then, you go and post something like this and I think, "I gotta have one of those."

Really, great job. It's beautiful. Craftsmanship appears to be top notch.

 

[Mtn_Brewer]

Admittedly, I haven't actually used it as a fermenter yet, but I've played around with the temps and it can hold a steady temp with a hysteresis band of 2 degrees. It's insulated well enough that the AC and/or heater don't have to cycle very often at all. Given the volume of the chamber, the 500 watt heater doesn't appear to be overkill at all. Overall, I m pleased with how it all turned out and I certainly lerned a lot along the way.

So there it is. I hope you all find this interesting and gives you some ideas. I'm anxious to see what upgrades others come up with.

As this style of fermenter doesn't appear to have a name, I will throw out the name "two-tier fermenter". It's easy to say and is accuratively descriptive IMHO.

 

[Dave37]

A truly great job. And an awesome work space by the way. If you brew as meticulously as you organize and build then I must say I'd like to try a mountain brew or two some day.

Cheers

Dave

 

[Mtn_Brewer]

Wow. Excellent build! How cold can you get the chambers with that AC unit?

While messing around with it yesterday I got the temp down to the mid 20's in the lower chamber. This was only for a few minutes though. I suspect if I tried to use it as a freeer that the coils would ice up. I usually lager at 36-40 degrees, so I think I'm safe.

 

[Mtn_Brewer]

A truly great job. And an awesome work space by the way. If you brew as meticulously as you organize and build then I must say I'd like to try a mountain brew or two some day.

Cheers

Dave

My theory is that OCD is only a disorder if you don't know how to channel it.

 

[Ryush806]

Awesome build! Let us know how it works with some fermentations going!

Also, if you don't mind me asking, about how much did that cost to put together?

 

[emjay]

My theory is that OCD is only a disorder if you don't know how to channel it.

By definition, it needs to result in substantial impairment in one's social, work, and/or academic life in order to be considered a disorder of any clinical significance. In other words, if it's something you are able to "channel" or to otherwise benefit positively from, it's not OCD.

 

[Mtn_Brewer]

By definition, it needs to result in substantial impairment in one's social, work, and/or academic life in order to be considered a disorder of any clinical significance. In other words, if it's something you are able to "channel" or to otherwise benefit positively from, it's not OCD.

I most definitely agree with you. I didn't mean to make light of a potentially serious mental health condition. If I offended you or others, I appologize. I realize I should have phrased my quote differently and given some back story. When Dave37 commented on my fastidious work, it reminded me of how my SWMBO often diagnoses me with having OCD when I get into projecting. When she gets annoyed I use the line about channeling OCD and remind her how much she actually likes the beer I brew, the trellises I've made, etc and she usually gives me a nod of agreement and then tells me I've got 30 minutes to clean things up. I'm sure others can relate.

 

[Mtn_Brewer]

Awesome build! Let us know how it works with some fermentations going!

Also, if you don't mind me asking, about how much did that cost to put together?

I didn't keep an accurate tally but I'd estimate it was about $1,200. This includes ~$200 that was spent on experimenting and screw ups. It wasn't cheap, but it is exactly what I wanted and should last for decades.

 

[Ryush806]

I didn't keep an accurate tally but I'd estimate it was about $1,200. This includes ~$200 that was spent on experimenting and screw ups. It wasn't cheap, but it is exactly what I wanted and should last for decades.

For sure! Probably on par or maybe cheaper than buying and modifying two big chest freezers and definitely a lot nicer!

 

[Mtn_Brewer]

For sure! Probably on par or maybe cheaper than buying and modifying two big chest freezers and definitely a lot nicer!

The other advantage is that I made the dimensions so I could fit and access 2 Blichmann 14.5 gal conicals in each chamber, should I decide to go that direction. It's not so easy to use conicals with a chest freezer.

 

[blakelyc]

This is awesome!!! I have a potentially silly question, though. Whenever I see these types of things they are usually cool-only. Is it not ever necessary to provide a heat source as well?

 

[Mtn_Brewer]

This is awesome!!! I have a potentially silly question, though. Whenever I see these types of things they are usually cool-only. Is it not ever necessary to provide a heat source as well?

Go back to the 6th post of the thread. The black boxes are the Broan 120 wall heaters. The Auber PID I used includes easy instructions on how to control both heat and cooling. Essentially, the main controller is set to cool and the low temp alarm output gets connected to the heater. Each has its own hysteresis band, so you basically dial in a high and low range. Given that my garage is only heated on demand and has no cooling, I'm sure I will need both functions given the hot summers and cold winters we get in Colorado.

 

[blakelyc]

Ah, I have no idea how I missed that. My own fermentation system will go in my basement in an area that is semi-conditioned, so I am debating a heater at all.

 

[zacc]

Awesome job man! My build was inspired by several different builds so its great to have been able to pass on the inspiration!

The ducting for the venting is very cool and the electrical box is a nice touch. It looks like you definitely went the extra mile on this build.

The only suggestion I would make is to maybe come up with a way to attach your temp probes to the side of your carboys. I would say this is really only critical during the first few days of fermentation. The wort can easily be 5-10 degrees warmer than ambient tempatures during this time. I just put the probe up against the carboy and cover it with a stack of folded paper towels held on by a bungee cord. Very low tech but it does make for more accurate fermentation tempatures. Of course you could use a thermowell or something to get even better readings but just doing something simple like this will help greatly.

The ingenuity of home brewers is one of my favorite things about the hobby. Of course the beer is good too .

 

[Mtn_Brewer]

Awesome job man! My build was inspired by several different builds so its great to have been able to pass on the inspiration!

The ducting for the venting is very cool and the electrical box is a nice touch. It looks like you definitely went the extra mile on this build.

The only suggestion I would make is to maybe come up with a way to attach your temp probes to the side of your carboys. I would say this is really only critical during the first few days of fermentation. The wort can easily be 5-10 degrees warmer than ambient tempatures during this time. I just put the probe up against the carboy and cover it with a stack of folded paper towels held on by a bungee cord. Very low tech but it does make for more accurate fermentation tempatures. Of course you could use a thermowell or something to get even better readings but just doing something simple like this will help greatly.

The ingenuity of home brewers is one of my favorite things about the hobby. Of course the beer is good too .

Thanks. I completely share your enthusiasm for invention.

I've struggled with the probe issue which is as clear as mud per my investigations. There seem to be equal proponents for probe in air, in a small liquid vial, strapped to the carboy and in a thermowell. It's so confusing. I was influenced by a poster in another thread who wrote that when attaching the probe to the most actively fermenting vessel in the fermenter the other carboys dropped to suboptimal temps and his FG's were too high. Have you monitored the temps of other carboys in the same chamber or had any similar problems?

I usually cool my wort to fermentation temps and then pitch the yeast. My plan has been to keep the chamber temp at the lower end of the yeast's range, anticipating that the carboy temp may be closer to the higher end early in fermentation but still be acceptable. Then, as fermentation slows, the carboy temp will come down to the lower end of the range. I bought a digital thermometer that I intend to strap to the carboy and insulate to see if my plan works out.

I'm also curious about your controller settings. Mine has a hysteresis band and cycle time. I've always used a hysteresis band of 2 on the Ranco controller I had hooked up to my chest freezer but I'm not sure exactly what to do with the cycle time. The range is 2-40 seconds with a default to 20 in On/Off mode. I understand the potential problem with frequent cycling but overshoot is also a concern. The thermal mass of a few carboys will likely affect the system greatly and I expect will help even out big swings in temperature. I'm going to brew sometime soon and anticipate a lot of experimenting/fine tuning but any advice on these settings would be appreciated.

 

[zacc]

Thanks. I completely share your enthusiasm for invention.

I've struggled with the probe issue which is as clear as mud per my investigations. There seem to be equal proponents for probe in air, in a small liquid vial, strapped to the carboy and in a thermowell. It's so confusing. I was influenced by a poster in another thread who wrote that when attaching the probe to the most actively fermenting vessel in the fermenter the other carboys dropped to suboptimal temps and his FG's were too high. Have you monitored the temps of other carboys in the same chamber or had any similar problems?

I usually cool my wort to fermentation temps and then pitch the yeast. My plan has been to keep the chamber temp at the lower end of the yeast's range, anticipating that the carboy temp may be closer to the higher end early in fermentation but still be acceptable. Then, as fermentation slows, the carboy temp will come down to the lower end of the range. I bought a digital thermometer that I intend to strap to the carboy and insulate to see if my plan works out.

I'm also curious about your controller settings. Mine has a hysteresis band and cycle time. I've always used a hysteresis band of 2 on the Ranco controller I had hooked up to my chest freezer but I'm not sure exactly what to do with the cycle time. The range is 2-40 seconds with a default to 20 in On/Off mode. I understand the potential problem with frequent cycling but overshoot is also a concern. The thermal mass of a few carboys will likely affect the system greatly and I expect will help even out big swings in temperature. I'm going to brew sometime soon and anticipate a lot of experimenting/fine tuning but any advice on these settings would be appreciated.

If you have multiple carboys in the same section at different stages there will always be some temp variance. I like to attach the probe directly to the carboy that's at the most critical stage to ensure its at the temp I want. This would generally be a carboy that's at the earliest stages of fermentation.

Like you point out, there are a lot of different options for temp probes. Really it's all about what works for you. I have just found attaching the probe to the carboys directly will give the most accurate temp readings. The temp of the air will change a lot quicker than the carboys so leaving the probe in open air will also cause the system to cycle on more frequently.

In my keezer I just have the temp probe in open air but there really isn't going to be any flux so it's not as critical. It still probably wouldn't be a bad idea to put it in water or something to reduce the cycles.

As far as controller settings, besides heat and cool temps mine has variance and min cycle settings(actual setting name might be different). The variance setting is how far above or below it will allow the temp to go before turning on. I just left mine at the default of 1 degree(note my controller is in Celsius). The min cycle settings is the minimum time before it will power back on the heat/cool after its cycle ends. Mine is set to 3 mins, I believe this is pretty standard for a compressor. I'm not sure if this is what your cycle time is referring to, regardless 2-40 seconds seems pretty low, are you sure that's not in minutes?

 

[Mtn_Brewer]

The maiden voyage is going well. I made a Kolsch and Dortmunder with intended fermentation temperatures of 60 and 50 degrees, respectively. The controls have required some monkeying to fine tune and I ended up doing some re-wiring to get the control I wanted. I was using the process low alarms for the heaters and the main outputs for the AC and cooling fan. This was a bit cumbersome to adjust and the temp averaged on the low side of my set value (SV) because the main control tended to over shoot cooling. The solution was to re-wire the main control (add 2 wires and subtract one) and use the high and low deviation alarms to control heating and cooling. I set the alarms for SV +/- 2 and the main hysteresis (Hy) at 1. So for whatever SV I input, the cooler comes on at SV + 3 and shuts off at SV + 1 while the heater comes on at SV - 3 and shuts off at SV -1. I turned the cycle time down to 4 sec and the minimal over shoot brings the temp exactly to SV. After just 2-3 cycles, the temps have been sitting exactly at SV for ~30 min without any change or cycling (see photo). Good insulation seems to be key. I will probably lower deviation temp to see how tight I can get the temp range with an acceptable amount of cycling. Overall, I'm pretty happy with it.

 

[nhwrecker]

Great build and great write up - I know you said that it was designed to handle the 14.5 g blickman's, but how many carboys fit on each level? I'm going to go back to the beginning and read it through again in more details, and I'm sure I'll have a few more questions, but well done!!

 

[Mtn_Brewer]

Great build and great write up - I know you said that it was designed to handle the 14.5 g blickman's, but how many carboys fit on each level? I'm going to go back to the beginning and read it through again in more details, and I'm sure I'll have a few more questions, but well done!!

Thanks.

It can fit 4 of the 6 1/2 gal carboys or six of the 5 or 6 gal carboys in each chamber with enough room for a blow off bucket. It can fit a 14.5 gal conical on the left and has enough room for another 3/4 carboys in front of the door. When I will be brewing 12 batches of beer at the same time is uncertain, but this is one project I only wanted to do once.

 

[PacificNWBrewer]

I can't tell you how much I LOVE this build! I really want to make something to ferment my beer as well as serve it. If the lower chamber can get 35-40, that's cool enough for serving. What do you think about installing 2 or 3 taps on the front where your chalk board and move your board up a little bit. Do you think it would work the way you it setup?

I'm in the process of designing something along this design and I'm having a hard time deciding on the direction. A chest freezer as the base with a chamber on top? Since I'm snobby and don't really want a used one, $400 for a new one is not my fav idea. An AC unit sounds good but I've been worried about the coils freezing up when running at low temps. It sounds like yours has done fine at lower temps... have you have any coil freezing issue?

Again, thanks for the great post!

EDIT:
after I posted this, I looked again at page 1 and noticed where the heaters are located. No room for tap lines there but what if the heaters were moved to the back wall instead of the front?

 

[Mtn_Brewer]

I can't tell you how much I LOVE this build! I really want to make something to ferment my beer as well as serve it. If the lower chamber can get 35-40, that's cool enough for serving. What do you think about installing 2 or 3 taps on the front where your chalk board and move your board up a little bit. Do you think it would work the way you it setup?

I'm in the process of designing something along this design and I'm having a hard time deciding on the direction. A chest freezer as the base with a chamber on top? Since I'm snobby and don't really want a used one, $400 for a new one is not my fav idea. An AC unit sounds good but I've been worried about the coils freezing up when running at low temps. It sounds like yours has done fine at lower temps... have you have any coil freezing issue?

Again, thanks for the great post!

EDIT:
after I posted this, I looked again at page 1 and noticed where the heaters are located. No room for tap lines there but what if the heaters were moved to the back wall instead of the front?

Thanks. Glad you like it.

So far it's been pretty cold here in Colorado so my first run has mostly relied on the heaters. They have performed well and are able to keep the temp in about a 3 degree range. I think they could easily be moved to the back. I already have a 6 tap upright keezer in my garage, so I wasn't thinking about taps, but I think that would be a feasible and very cool upgrade.

I'm not too worried about coils freezing, as the chambers are really well insulated and at 5000 BTU, the AC unit is certainly oversized for the job. I think most of the coil issues have been with people who build a "cool room" where a larger space needs to be cooled resulting in more frequent and longer cycles. Even then a couple of small computer fans installed to blow over the couls seems to have solved their issues. Controlling humidity is probably another factor but not one we need with much here in Colorado.

I actually had a chest freezer but I could figure out a way to adapt it to a 2 tier system that I was too psyched about. Others have done it on this site but they didn't meet my needs. The side by side option seems good with a fan and tubing system to cycle air between the keezer and fermenter but I don't have the floor space.

 

[PacificNWBrewer]

I've read a few other ac cooler posts but I still have a question. When the ac unit draws in air from outside the chamber, cools it and then pushes it into the chamber, where does the air that's already in the chamber go? Is there an exhaust port somewhere? Is this even an issue? Does the ac unit have a vent to exchange fresh air with cooled air?

Also, do you have dimensions for your setup? I'd love to reproduce it. My wife LOVED the idea so I need to work fast before she changes her mind

D

 

[Mtn_Brewer]

I've read a few other ac cooler posts but I still have a question. When the ac unit draws in air from outside the chamber, cools it and then pushes it into the chamber, where does the air that's already in the chamber go? Is there an exhaust port somewhere? Is this even an issue? Does the ac unit have a vent to exchange fresh air with cooled air?

Also, do you have dimensions for your setup? I'd love to reproduce it. My wife LOVED the idea so I need to work fast before she changes her mind

D

An AC unit draws air in the front of the unit, runs it past the cooled heat exchanger and pushes it out the top. The air in the chamber is just recirculated and not drawn from the outside. The fan on the outside blows over the outside heat exchanger to cool the refrigerant and dissipate heat. This is why efficiency of cooling goes down when it is cold outside the chamber.

I'll measure it and repost the dimensions.