A Homestead Walk-in Cooler II

Not very pretty, but it works!

In my prior post, I wrote about the reasons I needed a walk-in cooler.  In this post, I will give the instructions on how to use 2 Inkbird temperature override units to fool an air conditioner into getting your room down into the 35*F range.

Supplies:

1 – 3 gang electrical box (to hold the components)

1 – Receptacle (“plug in” or socket, in layman’s terms)

2 – Inkbird ITC-1000 Temperature Switch (best price through Amazon)

2 – 3 prong electric cords (old desktop computer power cords work well for this)

Extra wire (if your electric cords are more than 2 feet long, you can cut about 8 inches off each one to provide this)

1 – Incandescent night light fixture with 4 to 7-watt bulb, cover removed.

1 – Short, 2 prong extension cord

A piece of aluminum foil, approximately 3 inches x the width of the foil.  You will split this in two.

Instructions:

*To simplify things, mark the Inkbird units as #1 and #2.  Black Sharpie or other permanent markers work well.  Use masking tape to label temperature sensors as #1 and #2.

  1. Remove the female plug end of one of the cords.  NOT the end that plugs into the wall socket – that is the male end.  If your cord is over 2 feet long and has plenty of space to spare from where you will mount the unit to the wall receptacle, cut off about 8 inches.
    1. Remove about 4 inches of the casing.  Strip about ½ inch of the covering from the end of the black and white wires.  Cut the green wire down to about 1 inch long, fold back against the cord and tape it down.  The ground won’t be used on this wire.
    1. Put the cut end of the wire through one of the holes on the back of the 3-gang electrical box (you will likely have to punch the holes out).
  2. From your extra wire, cut 2 pieces each of the black and white wires, approximately 3-4 inches long, and strip about 1/3 inch from one end of each.  Insert the black wires into Port 1 on each Inkbird unit.  Insert the white wires into Port 2 on each Inkbird unit.  Strip about ½ inch from the other end of each black and white wire. Pigtail the black wires from each Inkbird to the black wire from the extension cord. Likewise, pigtail the white wires from each Inkbird to the white wire from the extension cord.  Connect the sensor wires to ports 3 & 4 on each Inkbird unit, making sure to match the units with the marked temperature sensors.
  3. Test operation by plugging the extension cord into a working wall receptacle. If working properly, both units will show the ambient room temperature.  If not working properly, check connections.  I typically have trouble with pigtail connections.
  4. Cut the female end from the 2nd power cord.  Remove about 12 inches of wire for later use. Put the cut end through another hole on the 3-gang electrical box.
  5. Remove about 4 inches of casing from the power cord. Using the strip gage on the receptacle, remove the covering on the ends of all three wires: black, white, and green.  Connect the white wire to the neutral side of the receptacle; the screws are usually silver.  Attach the green wire to the green/ground screw.
  6. Attach the black wire to port 7 of Inkbird 1. Using a 3 to 4-inch-long piece of black wire, stripped at both ends attach one end into port 8 of Inkbird 1.  Attach the other end into port 7 of Inkbird 2. Using another black wire, 6-8 inches long and with both ends stripped, attach one end to port 8 of Inkbird 2 and the other end to the hot wire screw on the receptacle.  The hot screws are usually brass.
  7. Attach the back covers to the Inkbird units.
  8. Plug night light into 2-prong extension cord.  Plug the cord into the receptacle on the temperature override unit you have just built.  Make sure the night light is turned on.
  9. To test, plug the 2 cords from the temperature override unit into a wall receptacle.  Adjust the set temperature on the Inkbird 1 to a bit higher than the ambient room temperature.  This should make the light bulb turn off.  If not, you may have a loose connection somewhere.
  10. I stacked the Inkbird units on top of each other and used shims to hold them in place in the 3-gang electrical box, then attached the receptacle normally with the screws that came with the receptacle.  I then cut a wooden plate cover to fit over the front.  It isn’t perfect, but it made it all a bit tidier.

Using the temperature override unit:

*I put up a small shelf to hold the temp override close to where the A/C is mounted.  It makes everything a lot easier if everything is right there.

  1. Remove the front cover and filter of your air conditioning unit.  Pull the coil thermostat out of its clamps.  Make a small opening in the filter to thread the thermostat out of the A/C and to thread the #1 temperature receptor into the A/C.  You’ll have to thread them through the cover as well.  I attached the temperature sensor to the clamps that held the coil thermostat.
    1. Wrap one piece of foil securely around the night light bulb.  Use the other piece of foil to hold the A/C coil thermostat close to the night light.  Make sure they are secure.
  2.  Plug the A/C into the wall receptacle.  Turn it to its coldest setting.
  3. Set Inkbird #1 to 32*F.  This will prevent the A/C coils freezing up.  Set Inkbird #2 to your desired target room temperature.  Use sensor #2 as the air temperature sensor.  In my case, I have Inkbird #2 set to 36*F.

In using this method, you do not have to modify your air conditioner and you can use whatever A/C unit you want, because the light bulb is the only thing that needs to go off and on.  The heat from the bulb fools the A/C into thinking the room is hotter than it really is. The light bulb will go off if the A/C’s fins are in danger of freezing up.

For more information, Google Coolbot , Inkbird, and walk-in coolers.  There are great ideas out there for building small-space walk-in coolers and I feel I’d just be repeating them if I tried to describe what I did here.

I look forward to hearing your thoughts!

I have edited this post to include the wiring diagram I came up with. I hope it is legible.

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