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

[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.

 

[sasky7777]

Great Job!

 

[tone_s]

That is amazing!

 

[PacificNWBrewer]

Just an idea. Taking the actual chamber as a guide, I made this.

Doors would hinge on the right side to access. It could fit 8 corny kegs or 5 carboys. I made the lower section tall enough to get a conical to fit inside (most likely have to make a new base for the conical as it is only 39" tall inside). The top will hold the same amount of cornys/carboys plus blowoff bucket/jar.

On the front, the chalk board idea is great! I intend to have it swing open (hinge on the right like the doors) and hide all the temp controllers behind it. The left side is about 8 inches think so there is more space for insulation of the duct work, the controllers and hide all the outlets.

The 5 taps installed on the front should clear the chalk board. I'll have a drip tray below them. The CO2 tank will need to be mounted next the to AC unit on the outside.

The AC unit would be on the left side as well as the heaters. For heaters, I would use the lightbulb-in-a-can method rather than wall heaters. The cold air would be drawn from the bottom to the top by a bathroom fan (80 cfm) that plugs into a regular outlet behind the chalk board.

The entire unit stands 7 feet tall by 3 feet deep by 5 feet wide with casters installed. Now, I'm a littler taller than the image of the girl (no jokes ) so it seems like I could still reach everything inside and out. I thought about removing it from my garage if needed and it can easily lay on it's back side should I need to move it somewhere else so I won't make it taller.

Seems like it should work... just a theory though. I still need to BUILD it.

 

[Mtn_Brewer]

Just an idea. Taking the actual chamber as a guide, I made this.

Doors would hinge on the right side to access. It could fit 8 corny kegs or 5 carboys. I made the lower section tall enough to get a conical to fit inside (most likely have to make a new base for the conical as it is only 39" tall inside). The top will hold the same amount of cornys/carboys plus blowoff bucket/jar.

On the front, the chalk board idea is great! I intend to have it swing open (hinge on the right like the doors) and hide all the temp controllers behind it. The left side is about 8 inches think so there is more space for insulation of the duct work, the controllers and hide all the outlets.

The 5 taps installed on the front should clear the chalk board. I'll have a drip tray below them. The CO2 tank will need to be mounted next the to AC unit on the outside.

The AC unit would be on the left side as well as the heaters. For heaters, I would use the lightbulb-in-a-can method rather than wall heaters. The cold air would be drawn from the bottom to the top by a bathroom fan (80 cfm) that plugs into a regular outlet behind the chalk board.

The entire unit stands 7 feet tall by 3 feet deep by 5 feet wide with casters installed. Now, I'm a littler taller than the image of the girl (no jokes ) so it seems like I could still reach everything inside and out. I thought about removing it from my garage if needed and it can easily lay on it's back side should I need to move it somewhere else so I won't make it taller.

Seems like it should work... just a theory though. I still need to BUILD it.

That is a pretty cool plan. The hidden control panel is a nice touch. I wonder if you could use a standard medicine cabinet for this. The bathroom fan I used was 70 cfm with a baffle that stayed closed in the horizontal position. I installed a fan control but I've been running it at full power and has worked fine.

Get on it!

 

[RussH]

Very nice build, and good 'documentation'. After recently getting into sours I have decided that more fermenter space is in order. Thanks for the inspiration.

 

[Mtn_Brewer]

Update.

I've run several batches through this thing and it has worked very well. The only trouble I've had was some icing up when I dropped the temp from 50 to 36 on a lager. I did what others have done and installed some computer fans over the grill, which has worked. I only put them on for lagering. For temp control, I decided that using thermowells was too much of a PITA, so I just got the high sensitivity stick-on thermometers for $3.50 a piece from my LHBS. Despite others reporting wide differences between the air and fermenter temps, I found the fermenters were within 1 degree of the set air temp throughout fermentation. I have the Auber controller using the high and low deviation alarms to control the AC and heaters with the alarms at 2, the hysteresis at 1 and the cycle time at 10. This has worked flawlessly.

Hope that helps.

 

[worthogg]

This is radical...nice work!!

 

[Noidios]

I'm looking at doing a 2 tiered chamber myself. For the purposes of my design, I'd like the tops chamber to be the cooler of the two though. Does this pose any problems?

In an effort to keep the cost down, my "cold" chamber will just be for cooling kegs (no heat needed for this tier) and the "warm" chamber will be for fermentation. My thoughts are to use a single dual stage fermentation controller with a probe in each tier and then use a home thermostat to control the transfer of cooler air to the fermentation chamber. Does this make any sense, or is it too early in the morning for me to be thinking about such things?

Thanks for all your hard work in sharing this project with us!

 

[Mtn_Brewer]

I'm looking at doing a 2 tiered chamber myself. For the purposes of my design, I'd like the tops chamber to be the cooler of the two though. Does this pose any problems?

In an effort to keep the cost down, my "cold" chamber will just be for cooling kegs (no heat needed for this tier) and the "warm" chamber will be for fermentation. My thoughts are to use a single dual stage fermentation controller with a probe in each tier and then use a home thermostat to control the transfer of cooler air to the fermentation chamber. Does this make any sense, or is it too early in the morning for me to be thinking about such things?

Thanks for all your hard work in sharing this project with us!

Putting the cool chamber on top may require baffles to prevent the cold air from falling and hot air from rising, which would both affect the efficiency of the set up.

The only dual stage temp controllers I know of use one probe and heat or cool based on the temp sensor and hysteresis. I'm not aware of a controller with 2 probes, but I could be wrong.

If the cool chamber doesn't need to be less than 50 degrees, then you may not even need a thermostat, depending on the AC unit you choose. The one I got from Home Depot cooled to 50 degrees on its max setting and its built in controller can be used to aim for higher temps. If you are going lower, then you would need a single stage controller or thermostat and then mod the AC unit like I did.

For the fermentation controller, you would need a dual stage controller to run fans to the cool chamber for cooling and to your heat source for heating.

If you are mostly an ale maker, this would be fine. If you want to make lagers, then you would want a more fine tuned control of the cool chamber.

Good luck!

 

[Mtn_Brewer]

One other thing about temp controllers. Remember to check the amps they can handle. The Ranco dual stage handles less per channel than their single stage controllers, so depending on what you are controlling you may need contact relays.

 

[Mtn_Brewer]

Cautionary update:

I bought a stir plate and actually started pitching recommended yeast quantities. With the more active fermentation, it became apparent that the air temp probe was not keeping the beer temps low enough. I decided to go the thermowell route, which turned out to be a rough go. Here's how not to do it.

First off, I didn't think ahead with my thermocouples. They weren't long enough and were too big for the 1/4 inch thermowells. They were also too well internalized, so when I tried to use them to pull the new wires through, they didn't budge. I ended up having to drill a new hole up top and use conduit to reach the lower chamber. The conduit was something I should have put in from the start. Once it was in, I decided to also put an outlet in the lower chamber. I connected it to a 3 way toggle switch so it could be on, off or cycle with the cycle timer I have on the circulation fans.

I bought the thermocouples for thermowells sold by Auber. I used their extension wire and connectors. They didn't work at all. The drift/temp swings were up to 15-20 degrees over 24 hours! Nothing I did improved this. I sent an email to Auber and nothing they suggested helped either. Ultimately, I scrapped the system and replaced both probes with Pt100 RTD's from Auber. Once I did this, the temp monitoring was flawless. I could have saved a lot of headaches and expense if I'd done this from the start.

Using thermowells caused my cycle times to get longer and I then had problems with the coils icing up on the AC unit. I tried high flow computer fans, which helped but if I pushed the system hard enough it still iced up. Instead, I used the thermostat on the AC unit to make a Cool-bot like set up. If you look back on how I monkeyed the thermostat to start with, you'll see that I didn't end up bypassing or disabling the thermostat, I just turned the adjustment screw down. This meant the temp control on the AC unit was still able to be used. With the unit at max with both chambers on, I slowly adjusted the dial control with a separate thermometer on the coils. I found that the unit I used has a hysteresis of 5 degrees. I tuned it to the point that it will turn off the compressor when the coil temps reach 34-35 degrees and turn the compressor back on when it goes back up to 39-40 degrees. The AC units fans stay on until the temp reaches the temp set on the control panel, so I took the computer fans out. With this system, I found I could run it full throttle and keep the top chamber at 50 and the lower chamber at 40 with no icing up whatsoever.

Just curious, anybody else follow in Zacc and my footsteps with this 2-tier system?

 

[zacc]

Sounds like you got it dialed in with the thermowells, I bet those work nicely.

I'm still just putting the probe on the outside with some paper towels behind it to insulate against the air in the chamber. I use a bungie cord to hold it on, this gets a pretty good measurement of the beer instead of the air.

I've thought about using thermowells, I'm sure it would be more accurate. I'm pretty happy with the results from the simple method I'm using now, but maybe someday I'll get around to switching to thermowells.

I always use starters with a stir plate as well. You definitely get a much more active fermentation, I can see why the open air would have been working before if you weren't making large starters.

I've been using my chamber for over a year now and just had my first issue with icing this summer. We had a week or so of 100+ weather and I had the bottom chamber set to about 38F. I got home from work one day and the unit sounded odd, upon closer inspection the coils were completely iced! I defrosted it and turned it up to about 45F and it was fine after that.

I had been running it at that temp for several months without a problem so I didn't bother to make any adjustments to the system. It doesn't usually need to be that cool anyways, so I will just be careful about putting it that cool when we are having a heat wave!

Great to hear that your unit is working out well for you! I'm very happy with how well mine has performed and am glad I went this route.

 

[smertz001]

The thermowells, do you put them into the brews? Or stick them to the side of the fermentors?

 

[Mtn_Brewer]

Update on heating system.

The above mentioned cooling mods are working great. Over the winter, I did some brewing through cold weather and the heaters were necessary to maintain fermentation temps. Because of the thermowells, the cycle times were long and the wall heaters were heating up to 150 degrees and the built in thermal cut offs were tripping. They are manual reset, so the heaters just switched off and stayed off. The wiring is such that the line in has the thermal switch and then the current branches to the fan and the heating coil. Here is my mod:

I found a self resetting thermal switch with an "on temp" of 105 and "off temp" of 115.

I spliced the switch between the current and the heating element.

I kept the stock switch in place.

I kept the wiring to the fan intact.

Now, when the thermowell reads low, the temp controller provides continuous power to the heater. The fan runs continuously but the heating element turns on and off as the air passing through the system fluctuates from 105-115. If the switch failed in the "on" position, the built in manual switch would trip at 150 and the whole thing would shut down.

I have used this system with a converted 15 gallon keg fermenter with a thermowell conversion kit I got from brewers hardware. It has worked flawlessly. It has also worked with this glass fermenter thermowell mod I made. I just replace the dip tube with a thermowell.


Sent from my iPhone using Home Brew

 

[RussH]

Just went to RONA yesterday and picked up the lumber to start my build. I've been watching this thread since the start, and have been dreaming of the day I could build my own. Finally making it happen. I have redesigned the structure a bit to optimize material, and fit 6 carboys top and bottom, but the overall idea is going to be the same.

Thanks for documenting it.

 

[c0bra]

Love this build. I hope to attempt it soon. I noticed that someone asked for dimensions at one point but I never found a reply. Were they posted and I missed them? It would be some helpful guidance for those of us with less DIY-ability.

 

[RussH]

Here are the dimensions I am going with, after rereading the first part of the thread, these are probably quite close, as they've been worked to maximize material. I also have some space constraints I am working with, but this will fit 12 6 gallon carboys.

 

[Mtn_Brewer]

I've been away from brewing for awhile but now I'm back at it. I was wondering how these projects worked out. Post up!

 

[Warrior]

Nice job!

 

[William656]

I've heard of issues with dampness and mold. Any problems here? It's been a few years. Curious how this is holding up.