Fridgecubator! (Otherwise Known As Cheap and Consistent Temp Control on a Dime)

Introduction: Fridgecubator! (Otherwise Known As Cheap and Consistent Temp Control on a Dime)


So, I'm a big lurker here and this is my first post!

I figure it'd be proper to show you guys my lab, considering the name of the contest I'm entering this in,
here's a pic of the entrance to my lab! (nevermind that gap there, it's not the most recent picture)

pic 1 - entrance to lab
pic 2 - from within the lab to the right of the entrance, my cleanroom! to the left, my bulk incubator!
pic 3/4 - better pic of clean room and incubator
pic 5 - inside my bulk incubator, so shiny! (double layered, outer/inner of mylar, sandwiching foam insulation boards, structure built on the interior, so as to allow easier shelf modification)
pic 6 -  my clean room, and the fridgecubator!

all of this I built spending hardly any money (comparative to the possible costs that is haha)

Before we get started though, let me tell you a bit about myself.

A. I'm entirely self-taught.  Never took any classes on mycology, never took any lab chem or bio classes (excluding highschool), I studied philosophy instead.

B. I'm not much for planning

C. I hate spending money

D. I wrote the business plan, won the business competitions, landed the investments, built, planned, organized everything by myself for my states first organic mushroom farm/mycoremediation research lab

Currently we've written, planned, applied, won, and are currently operating two separate grants from the city to come up with a cheap and simple organic solution to soil erosion problems within some of the cities parks.

I've only mentioned all this to verify the functionality of my devices, one of which I'll reveal, not, because I jealously guard my secrets and inventions, only because the vast majority of the photo documentation of many of the inventions I use in my lab is lost in my friends nexus, which if any of you have bought, can hopefully sympathize with, seeing as how this is the third time its crapped out on him, to the detriment of this instructable.
Hopefully, you guys will read this, and give it equal merit as that which is given to the picture heavy applications to the "build my lab" competition

So, I give you.............drum roll......................

(move to step one)

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The problem - even temperature application, using as little "new" material as possible, while spending the least amount possible in its construction, and in its use (efficiency)

As you know (if you incubate things)
precise temp control can be the difference between 5 days, or two weeks,
and when you operate a business based on a known incubation time,
the difference of one degree can mean lags in production schedules that'll haunt you for months.

I've built many an incubator, 
started out with just a cardboard box and a red lightbulb hooked to a thermostat scavenged from an old car.

However, refrigerators are already insulated!
refrigerators already have plumbing installed to exchange heat evenly!
There are lots of old broken refrigerators everywhere that you can get for little to nothing!
with a found fridge, all one needs really is a pump, two thermostats, some tubing, and a bucket.


Contrary to the name though, it's not actually a refrigerator!
It's technically an upright freezer,
why an upright freezer, you may ask?
well, unlike your usual home refrigerator,
upright freezers have coolant coils built into each shelf,
which, if you snip those coils at the proper places,
disconnecting those coils from the coolant system,
allowing you to connect your own system to those coils!

Essentially, what we're doing is we're disconnecting the coolant pump, condenser, and reservoir from the heat exchange coils built into the shelves, and basically building a mini hot-water-heater, and hooking it up to the freezer in place of what used to be there.

Additionally, freezers are much more effectively insulated than a refrigerator,
which is only a bonus! 

And on that note,
lets get to the materials needed list, shall we?

(I'm going to speak of the operation of the materials, instead of pointing out specific materials, since there are many ways to do this, and all junkyards are different)
1 - upright freezer [doi!] (the cheaper the better, better yet, hop on down to your local dump, and buy a broken one from the junk man, I got mine from the basement of my parents, who were too lazy to get it out of the house and throw it away)

2 - water reservoir (I used what I had on hand, which, in this case, is a one to one and a half foot section of 4 inch pvc with an end-cap, although, literally, anything works)

3 - heat source (in this case, an immersion heater scavenged from an electric hot water heater found at... you guessed it, the dump!) (you can use fishtank heaters, electric tea kettle heaters, or electric range heaters, any heat source really, I've used many different kinds, they all work)

4 - controlling device for your heat source (in my case, I dropped a bit of coin to use a cycle timer, however, there's a million ways to skin the cat, digital timers, analog timers, hot water heater thermostats [sorta perfect], creativity counts when your resources are minimal)

5 - water pump to circulate everything ( again, anything works, in my case, I got a tiny 250 GPH fishtank pump from a friend for doing a few loads of his laundry)

6 - thermostat to control when the pump turns on and off (same deal as the pump in my case, different friend, I used a reptile tank thermostat, but basic home thermostats, really any sort of thermostat works, the higher its accuracy the better)

7 some tubing to connect it all! ( the interior diameter of the tubing you use will be defined by the size of the coils inside of the freezer, and how you wish to connect to it, in my case, I used silicone tubing that is 1/4 interior diameter, I slipped the tubing over the freezer plumbing (exchange coils) and used hose clamps to make sure it all stayed put and was water tight, also, use beer brewing tubing, it can take the heat)

8 - adhesives!!!!!!!!!!!   No, Seriously, adhesives.  In my case (i've been using that phrase a lot haha) I used everything you could imagine, hot glue, silicone, pvc glue (every single type) epoxies, duct tape, and even liquid latex!

Although, lemme impart some of my experience on y'alls hur, epoxy, go with epoxy, marine epoxy, or instant epoxy, that stuff that comes in the syringes at home depot? yeah thats the stuff, it'll save you a lot of heartache and its not too too pricey ('bout $5 a syringe, and it should only take one or two (get three))


For how to slap-it-all-together-so-it-don't-fall-apart, please continue to step 2!


Step 2: How-to-Slap-It-All-Together

Here, unfortunately, is where the lack of pictures begins to show.....

I had pictures of each piece as it was put together with another piece, 
or rather, my roommate/lab assistant/agar-slave had these pictures,
had 'em on that nexus I mentioned, 
man, screw nexus, or nexi?

grammar aside,
onto the How'd-He-Do-it  section!

I've posted the same pictures here as I did on the previous slide, both because I got nothing better,
and I'll try and point out everything on them in detail for you.


That black thing in the top left of the fridge wall?
that is the thermostat that I use to control when the pump circulates water through the system, adding heat.
its a zoo-med repti temp comtrol unit, think they're about $20 new (any thermostat works though, as long as it has an external probe)

I've placed the probe of the zoo-med inside of the incubator, and I've plugged the pump into the zoo-med thermostat.  Whenever the temp inside the incubator drops below a set temperature, the pump turns on, circulating hot water through the system.
that yellow tape around the black wiring? that's the pump power cable, the pump is a submersible pump and is inside of the water reservoir, which is that pvc tube.


the big white vertical tube? yup, it's the water reservoir, I was thinking about neatening it all up and putting a cap on it, bundling the wires and tubing, but I like to easily add water and see the level of the water, so I said screw it (the more insulated your reservoir, the more efficient it is)

The tube is just 4 inch pvc, which is a very common size of pvc, the length that you make yours determines the overall capacity of the reservoir (watch out though, the more water, the heavier it gets, which exhibits more force on the end-cap and all the seals)

at the bottom of the resevoir is the immersion heater


just your basic 120v 1500w immersion heater that you can get at home depot, or scavenge from small electric hot water heaters.
(again, any heat source works)
I bored a 1 1/4 (one and one quarter inch) hole in the end cap, and screwed in a 1-1/4 inch male - 1 inch female cast-iron pipe fitting into the hole.  doesn't matter what it's made from, as long as it's metal (those immersion heaters get really hot at their surface, and anything in direct contact has to be temp resistant)

I used marine epoxy to seal the joint on the inside of the end-cap (before attaching the end-cap to the pipe, of course)
and applied a bead of silicone to the outer joint (any silicone, it's all got the same temperature parameters, no need to spend extra dough on "high-temp" engine silicone, after all, silicone is silicone, chemically speaking)
silicone caulking is cheap and can be easily found almost anywhere around the globe, and can be used for all sealing purposes in this device (don't HAVE to use epoxy, it's just nice, real nice)

After attaching the pipe fitting, I simply screwed in the immersion heater to the pipe fitting (immersion heaters are 1 inch diameter male threaded, standard) and snugged it down with a wrench (immersion heaters usually have a gasket, if yours doesn't, get creative, those adhesives I mentioned, they're really important for "creativity")


So, now you've got a big 4 inch pvc tube with a heating element attached to the end of it.
Well, you can't just plug the thing in, it'll just be on constantly, boiling all the water off, and melting anything you have in that reservoir, and probably screwing with the seals, and breaking down any adhesives.
So, how do you control your immersion heater?
many different ways, of course,
I eventually ended up using a cycle timer, but that was only for easy temp control
(cycle timers have two knobs, one knob determines how long the device is on, the other knob controls the time between "on" periods)
you can use digital timers, or analog timers, 
my only warning is to make sure that you have enough intervals that you can program,
you don't want to be confined by your timing device,
I have mine set to about 1-2 minutes on every half hour or so
so you want at least 24, if not 50 on/off options in your digital or analog timer

Or, screw timers, just scavenge the thermostat from the electric hot water heater that you already scavenged your heater from!

but simply, plug your immersion heater into your timer, and plug the timer in (add water first! never run a heater dry, doi)
follow the orange wire from the bottom of the pvc tube, up and over to the right, up to the black box in the top right of picture, thats my cycle timer (I hotglued a powerstrip to the back of the incubator, I went through a hot-glue phase)


I've described everything in the picture but what's inside the reservoir (besides the heating element)

you can't see it, but theres a pump in that pvc tube,
as I mentioned, its a small 250 gph model, usually costs about $20 brand spanking new, but most fish tank enthusiasts have a few spare.

You can get fancy with it, you can drill holes in the pvc to allow for the power cable and in/out water lines to connect directly to the pvc tube, heck, you can even paint the dang thing if you'd like!

I, however, am a believer in the idea that form follows function, not the other way around.
So I just dropped the pump in the reservoir after hooking it up to the output line, and threw the return line from the incubator right into the top of the reservoir, works perfectly, and, in all actuality, makes for a lot less seals to worry about failing. (that's an important one right thur mmHmmm)
(those red circles with tubing coming out of them to the right side of the pvc reservoir? those are my in/out water lines connecting the reservoir to the heat exchange coils inside of the upright freezer, you can see that they're both just dropped in to the top of the reservoir)

To attach my own water lines to the heat exchange system that already exists in upright freezers, I just drilled holes into the walls of the freezer just large enough to fit the tubing that i would use, and make sure that the holes I drilled were lined up with the plumbing that i was going to connect to, then simply feed your in/out water lines from your reservoir, into the holes, slip the tubing over the pipes inside the freezer, and use hose-clamps to make sure it all stays put!

And, just to clarify, if you can see the picture of the jars inside the incubator, you can see the tubing running under each shelf, that's the plumbing that i'm referring to when I mention heat exchange coils.
The details on where you disconnect that plumbing from the coolant pump/condenser/reservoir is entirely up to you, and your aesthetic preferences on where you want everything to go, just make sure you have a continous loop of plumbing from one end to the other in your system, and you should be great!

And thats it!

Not that complicated, doesn't take much, and what it does take is some pretty common stuff that you can find pretty much anywhere, that isn't expensive!

I think I spent about $10 all told, not counting the cycle timer (it's not necessary, there's much cheaper ways to perform that function)

Pump thermostat - free (from a friend)
Pump - free (extra a friend had)
Heater - free (scavenged)
heater controller - (I'm not counting this, I should of just used the thermostat from the hot water heater that the immersion heater came from in the first place hahaha
pvc - free (scrap)
tubing - $5
adhesives/clamps - $5

It stays within +/- 2 degrees of target temperature,
I shit you not, it's the heart of my farm, and it's my baby.

Step 3: Bonus!

Oh, and here's a glovebox built from scrap plywood, an old bathroom fan, a new vacuum hepa filter, some silicone, and some cow insemination gloves!

the big thing here is the gloves, actual glovebox gloves can cost hundreds of dollars, however, a box of cow insemination gloves can cost as little as $5 and can be found at most dairy/cow farms or farm supply stores.

I used a handheld jigsaw to cut the arm holes, and stuck 4 inch pvc connectors not the actual 4 inch pipe, but the connectors into the holes I cut  (connectors are a bit larger so they can slip over 4 inch piping)

But, this is just an extra bit of adivce, just, if you're trying to build a glovebox, don't shell out the ridiculous amount of money for "glove box gloves"  just get cow insemination gloves!

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