My semi walkin 5000 btu fermentation chamber

[n240sxguy]

Alright everybody, drumroll please.




Cymbals crash. Da da da da.

Here's the ghetto, half done, gotta do this before I go to work this morning version. It is mostly done. Just need to cut a hole to mount it. I took the front cover off the A/C, spread a couple fins, and put the sensor in there. It was super easy to wire. Sensor in, power in, disconnect out put from original controller, and wire this one in that circuit. Seemed to be working pretty well for the 10 minutes I had to watch it. I had the door open checking on it, so it was too warm for it to really frost up. I set it at .5 C, differential 3 C, and timer for 6 minutes. That should give it enough time to thaw out if it does freeze up. Gotta wait til the rest of the house wakes up now so someone can go check on it for me.

 

[n240sxguy]

It was holding at 55 at 8am with the A/C shut off, and no frozen coils. I may have finally tamed this beast. When I get my batch out of there I'll see how low she'll really go.

 

[limulus]

Sounds interesting. I have to read through this again to figure out what you've done. If it allows you to go below 40F, then you've figured out a way to make your own CoolBot for probably $200 less.

 

[n240sxguy]

Sounds interesting. I have to read through this again to figure out what you've done. If it allows you to go below 40F, then you've figured out a way to make your own CoolBot for probably $200 less.

It basically does exactly what a coolbot does. The only difference is how it controls it. It cycles power to the unit vs tweaking the factory sensor. I don't know if it would work as well without the time delay keeping the fan blowing. I do admire the compactness and simplicity of the coolbot though. I'm not trying to take anything away from it as a product. Also, my way wouldn't work with a larger digital A/C since they wouldn't just fire back up when you reapplied power.

 

[Cape Brewing]

One tip for anyone else thinking about doing this... use a vapor barrier. Wrapping the entire thing (between the studs and sheeting) with 6MM plastic will save you a ton of headaches on frosting up.

Mine (in my gallery) has kept a steady 41 degrees for years. I use mine as storage for my serving kegs and run my draft lines from it.

Vapor barrier is a huge, huge help. To finish mine off, I simply wired the A/C unit to a PID (like in this thread) but then wired the fan to run 24/7. It circulates the air int he walk-in so I don't get any variation in levels, it instantly defrosts the coils if I happen to get a little frost, and those fans draw nothing in terms of power so it's not like my electric bill is sky high.

 

[n240sxguy]

That's a good idea about the vapor barrier. The only reason I didn't use that is the foam sheets I used are impervious to moisture, and the seams are taped. The bottom doesn't have that, so I may coat it with something. It would only take one wire nut to run my fan 24/7. I wasn't sure how long the motor would stand up to that, and I didn't want to have to replace the A/C because the manufacturer use a cheap motor and it burnt out.

 

[Cape Brewing]

my last A/C unit... which... I'm not joking, was at least 11-12 years old when I hooked it up, ran 24/7 for about three years. I finally replaced it with a new model (fan was still running the day I disconnected it) and my new one has been running a solid year straight.

I used the same foam sheets... I would still do the vapor barrier.

 

[n240sxguy]

Good to know they can last that long. I hope the new ones are as well built as the old ones. I've been curious about the cfm rating of an A/C fan. I haven't seen any numbers to compare with a computer fan. I know it's nowhere close, but I'd like to know none the less. I think one or two computer fans would move enough air to keep the temp constant. I also wonder if it's better on the fan to be running nonstop vs switching on and off.

Better to over prepare than under prepare with the vapor barrier. My sheets are glued to the studs so too late for mine.

 

[n240sxguy]

Got the box tidied up a bit this morning.













It was sitting at 42 before I shut it off to work on it. I set it to 35, so I'll see how far it will drop it by the time I get home this evening. I hated the wire nuts I had in there, so I got a terminal strip from RadioShack; and put spades on all the wires. Much better connection in my opinion. I didn't attach the relay socket because I ran out of time. I may attach it this evening.

 

[Yretsof]

Thats a good looking setup. Nice job. Do you have controls or refrigeration experience or are you just going by the seat of your pants? I would like to do a ferm chamber like this, but a bit larger. Maybe an 8' cube or 8x12. I am not a big lager guy so I wouldnt need to get it down to the temps you are taking it too.

 

[n240sxguy]

Thats a good looking setup. Nice job. Do you have controls or refrigeration experience or are you just going by the seat of your pants? I would like to do a ferm chamber like this, but a bit larger. Maybe an 8' cube or 8x12. I am not a big lager guy so I wouldnt need to get it down to the temps you are taking it too.

Thanks. I used to sell industrial controls, and went to Allen-Bradley control school to learn about their products. I really enjoy the problem solving aspect of tinkering with controls stuff. I've seen several chambers plenty bigger than mine that are running fine. I may build a bigger one someday. Or tear this one down to add to it.

 

[n240sxguy]

I mounted the relay base to the panel when I got home. Down to 44. I tweaked the controls to have it stay on longer. Hopefully get to the 30's soon.

 

[n240sxguy]

It looks like the best I can do without more insulation is 44-45. I wish it could go lower, but I've tweaked settings every which way and that's all I can get. It has been 80-90 with 60-90% humidity about every day, so I'm proud of my 44 either way. A couple computer fans, or the internal fan running constantly, may get me a couple degrees. I may give the internal a shot.

 

[Yretsof]

Have you thought about an insulation wrap around the outside? Like they do for hot water heaters. I bet you could wrap it for inder $50. I'd like to see you get it down to the lower 30s also. (I was a refrigeration guy in a former life!) But once you get down that low your gonna have freezing problems that can only be corrected by defrost cycles. But I have a feeling at this point its more about bragging rights.

 

[n240sxguy]

Have you thought about an insulation wrap around the outside? Like they do for hot water heaters. I bet you could wrap it for inder $50. I'd like to see you get it down to the lower 30s also. (I was a refrigeration guy in a former life!) But once you get down that low your gonna have freezing problems that can only be corrected by defrost cycles. But I have a feeling at this point its more about bragging rights.

Pretty much correct about the bragging rights. I'm gonna try to sweet talk an engineer at work, and try to get my hands on a thermal imaging camera. I'd like to see exactly where my heat losses are before I go throwing money at the wrong things. It pretty much has to be the seal at the door and around the A/C. At the very bottom of the door I can feel the slightest amount of cool air. I already sealed it up pretty good, but it could use a little more. I can't feel any other possible leaks. That's why I'm hoping to be able to "see" them.

 

[honreth]

I noticed several of the builds on this thread all looked nice, loved the side by side, but one thing I am not noticing is any kind of weatherstripping around the door... Is the foam insulating working in place of this?

BTW Nice build all the way around.. maybe one day when I get a conical I'll have something like this set up.

 

[n240sxguy]

The way the foam inside is placed, the hinge side door foam goes in front of the chamber foam, and slides inside the other three sides. It makes a very good seal. I have added a small piece of foam weatherstripping at the top and bottom of the latch side of the door to get an even better seal.

 

[armymedic942]

I was having a lot of trouble getting my ferm chamber that I built around a bar fridge to cool below 70...so I was inspired by by your build and bought and air conditioner. I have a dual stage controller, but right now I just have it controlling an outlet to which the AC is connected. Lowest temp I can achieve is 60 due to the internal AC thermostat. How do I bypass it. PLEASE help

 

[n240sxguy]

I was having a lot of trouble getting my ferm chamber that I built around a bar fridge to cool below 70...so I was inspired by by your build and bought and air conditioner. I have a dual stage controller, but right now I just have it controlling an outlet to which the AC is connected. Lowest temp I can achieve is 60 due to the internal AC thermostat. How do I bypass it. PLEASE help

If its a little $99 like mine, it should have a bulb and capillary type temperature controller with the bulb placed in front of the evaporator coils that are inside the chamber.



Those two little clips are where mine was attached. I removed the cover, and bent the bulb and capillary (very carefully!) around to the outside of the unit. Still within the cover of the A/C, just on the outside next to the compressor. Now it just reads the ambient temperature on the outside of the chamber. That will get you below 60. It does get increasingly harder to maintain the lower you go. I pretty much stopped at 44. That's all I could get. As the weather gets cooler, I may be able to go lower. If ambient gets below 60, I may have to wire up a tiny light bulb to heat the A/C's temp controller, but I'll cross that bridge when I get there.

 

[armymedic942]

Thanks....I will let you know how it turns out
As long as I can get down to 45, I can make Lagers

 

[Yretsof]

If its a little $99 like mine, it should have a bulb and capillary type temperature controller with the bulb placed in front of the evaporator coils that are inside the chamber.

Those two little clips are where mine was attached. I removed the cover, and bent the bulb and capillary (very carefully!) around to the outside of the unit. Still within the cover of the A/C, just on the outside next to the compressor. Now it just reads the ambient temperature on the outside of the chamber. That will get you below 60. It does get increasingly harder to maintain the lower you go. I pretty much stopped at 44. That's all I could get. As the weather gets cooler, I may be able to go lower. If ambient gets below 60, I may have to wire up a tiny light bulb to heat the A/C's temp controller, but I'll cross that bridge when I get there.

Have you tried to remove the thermostat circuit all together and wire through that part of the circuit? Should be as simple as unplugging 2 wires and tapping them together.

 

[n240sxguy]

Have you tried to remove the thermostat circuit all together and wire through that part of the circuit? Should be as simple as unplugging 2 wires and tapping them together.

I think it comes out of the temp selection knob on the front, and there's several wires coming out of the back of it. I would either have to open it up to wire the circuit together, or work around the whole selector switch. I was playing around with those settings when I was trying to get it to get colder. I found that it did a little better if it wasn't maxed out. If set all the way on cold it would freeze the coils up quick. After I got my second controller hooked up, it would kick the A/C off, then wait for the timer, then turn back on; and just keep repeating the cycle. When I backed the temperature knob down a little, the A/C wouldn't work as hard and freeze up. So, after all that, I don't really want to bypass that whole unit.

 

[armymedic942]

I tried moving the temp probe, but now my fan wont kick in.....im about ready to abandon the air conditioner altogether. I have a small deep freezer that I am thinking about stipping the coils and compressor out of

 

[n240sxguy]

I tried moving the temp probe, but now my fan wont kick in.....im about ready to abandon the air conditioner altogether. I have a small deep freezer that I am thinking about stipping the coils and compressor out of

Mine stripped down without any controls at all is set up like this: fan switch set to cold/hi, temperature set just a little off the coldest setting, and the bulb that was on the front is ran along the left side toward the compressor. Set up like that, it should run as soon as you plug it in, and basically never shut off. Is the compressor kicking in? Check the GFCI built into the plug end. That thing gave me a panic attack at one point. I didn't realize I had tripped it.

 

[crackhead7]

what size and where did you buy the junction box that you mounted your controller in?

 

[n240sxguy]

what size and where did you buy the junction box that you mounted your controller in?

It's a 6x6x4 Cantex PVC box from lowes. About $11.

 

[crackhead7]

Thanks, it is a nice size. I have a STC-1000 control box to build this week for a fermentation refrigerator. My last controller box was built out of a project box for my keezer and I like the Idea of the PVC Junction box better and its probably cheaper to boot.

 

[boredstate]

This build looks great and I have a similar setup, but I have a question. I have no experience with an STC, so go easy on me:

I have a Ranco dual stage that I'm using to control my ferm temps with a window unit. Cool connection cuts the A/C unit on & off and the heat cuts a fermwrap on & off with the temp probe in the vessel with a thermowell.. It's 5k btu unit with analog controls that's untouched. I have a second identical unit that I'm doing some testing with and completely bypassed the thermostat on it. There are only 2 leads going into the thermostat, so I disconnected them and placed a jumper between them so the compressor runs when the unit is on. Obviously this causes it to freeze up.

So my question is this: Can I use the STC (or other device) to cut the compressor on & off without trying to supply it with 110v as the temp of the fins reaches 0*C? I really just need it to break & complete the circuit like a mechanical switch and not supply power to it.. Right?? Or is that exactly what the STC does?

 

[n240sxguy]

Yeah, all the STC does is operate an internal relay, just like the Ranco you have. Exactly the same process. Too hot = on. Too cold = off. You will actually go below 0 C before it freezes up. Mine is set to -8 C. Hope that answered your question.

 

[boredstate]

Thanks, so just to clarify.. No power will be supplied to the connection then? I don't want the a/c unit to catch my house on fire. but srsly.

 

[n240sxguy]

Mine runs to the outlet that the A/C is plugged into. What you run into is if the controller is still wanting it to be colder, and the A/C is frozen up, it will just run forever. That's what the second controller that I have is used for. It monitors the coil temp, so if it gets cold enough that it is freezing up, it turns off the compressor for a set period of time while the fan continues to run to defrost the coils.

 

[armymedic942]

So I have the AC unit working...it is cycling fine with no sign of freeze up, however i still can't get the temp below 55 F. i read about this in another thread :http://www.storeitcold.com/index.html, and am seriously thinking about getting one unless I can find a cheaper way to squeeze 10 more degrees out fo my current setup. ideas?

 

[n240sxguy]

So I have the AC unit working...it is cycling fine with no sign of freeze up, however i still can't get the temp below 55 F. i read about this in another thread :http://www.storeitcold.com/index.html, and am seriously thinking about getting one unless I can find a cheaper way to squeeze 10 more degrees out fo my current setup. ideas?

Read back through my setup. Mine does what the coolbot does, only cheaper. Where did you put the A/C's temp sensor? What does your temp controller say? What temp do you have it set for? It shouldn't cycle off until it reaches the temp that your controller is set to.

 

[armymedic942]

I moved the AC temp sensor right outside of the plastic casing. I have the unit set on "Hi Cool". The fan runs non stop, and it seems like the compressor kicks in once or twice per hour and runs for about 2 min. probably a default on the unit, that doesn't let it cool too low. getting frustrated

 

[n240sxguy]

Take a picture. Is the sensor outside your fermentation chamber? That's where it should be. Take the whole case off the A/C and put the copper bulb on the outside next to the compressor. That will keep it warm enough that it won't shut off. Then your controller will turn the whole unit on and off.

 

[armymedic942]

Take a picture. Is the sensor outside your fermentation chamber? That's where it should be. Take the whole case off the A/C and put the copper bulb on the outside next to the compressor. That will keep it warm enough that it won't shut off. Then your controller will turn the whole unit on and off.

I don't have a lot of copper to play with but I will give it a shot

 

[n240sxguy]

I don't have a lot of copper to play with but I will give it a shot

To do it the way I did you'll have to take the A/C out, and sit it on the ground. Take the entire cover off of it. See if you can take that metal cover off that is limiting your access to the copper capillary. Then you will be able to move that bulb wherever you want to. You want it on the outside of the unit where it is measuring the temp of the room, not the chamber. By moving it where you did you kept it from sensing the temp of the coils, and cooled the chamber off a little more in the process. Be very careful that you don't kink that copper capillary. Put the cover back on, and reinstall the A/C.

 

[n240sxguy]

Look at these two pictures. The capillary tube is the one in the clear jacket coming out of the A/C's temp controller in the first picture. Follow it out and you'll see where I ran it down, then along the bottom, and tucked it back behind the compressor. Yours may not run to the exact same place, but anywhere back there will be warm enough to keep the A/C running. Just don't put it next to the cold line coming out of the compressor that goes to the evaporator coils. It could get too cold there.

 

[armymedic942]

This is what I did. Now I wait with fingers crossed





Here is a view of the chamber itself




I put a window in one end so I don't need to open it to check fermentation progress.

 

[n240sxguy]

That should get you where you wanna be. Did you cut the sides out of the fridge? Is the hole in the end where the A/C goes? Where's the window? The only thing that will limit you now is insulation. With the size chamber you have, it will probably get down low enough, but the amount of time that the A/C runs will depend on how well it is insulated and how air tight it is.