Upgrading the Larder

My wonderful ex-refrigerator that was turned into a larder needed a functionality face lift. My temperatures were accurate but the larder was inefficient when it switched on and off every second. The PID controllers allow more precise control when it comes to temperature and it is more affordable.

To get this done I invited my sous chef and lead line over, and after a six-pack of beer we were able to successfully attach the PID controller. The wiring took a moment of thought, just trying to remember what all the abbreviations meant from the last project I used a PID on was the most challenging. Once we deciphered the little black box we began to disconnect the old thermostat and plug the wires into the PID.

What you will need for the upgrade:

Auber PID Controller – $42.55

K Type Thermostat – $7.55

This should be all you need if you have extra 16 gauge wire, if not pick up another roll of white and black.

  • Unplug your main power source so you do not get zapped!
  • When you remove the old thermostat make sure to mark the three wires: Red = Hot from wall, Blue = Light/heat source hot, Yellow = Condenser hot.

  • Looking at the back of the PID controller the picture below shows where the wires will go.

  • Thermostat: Starting on the left with slot 9 and 10, plug the red end into 9 and the yellow into 10.
  • Looped green wires: You only need a short wire for these next two. One end goes into slot 14 and the other goes into 4 with the start of a second wire, this second wire ends at slot 1.
  • With slot 1 is your main power from the outlet, therefore the one that was RED going into the old thermostat now goes into slot 1.
  • Neutral, normally white but since I ran out of wire I made it green, this will go from slot 2 on your PID to the cluster of neutrals anywhere in the circuit.

  • Here you can see that I have my neutrals bundled and my ground wires bundled, again the wire going from slot 2 will connect to the neutral bundle.
  • Refrigerator Condenser: The hot end of the condenser will go into slot 13
  • Heat Source: The hot end of the heat source will go into slot 5

To Re-cap:

Slot 1: Main power line from the wall and one wire ending at slot 4.

Slot 2: Neutral, this wire should join the rest of the bundle of neutrals.

Slot 4: The end of the wire from slot 1, and the beginning of a wire that will be looped to slot 14.

Slot 5: Hot wire from the heat source.

Slot 13: Hot wire from the condenser.

Slot 14: The end of the wire from slot 4

Empty Slots : 3, 6, 7, 8, 11,12

  • You should now have a PID controller that will turn on and off a condenser and a heat source for your larder. The benefit of having a PID is that it can be a lot more precise with a smaller margin of error. Since I put it in my larder has kept a steady 58° with very little fluctuation in temperature.

Next step is to program the little black box, this took me a while to figure out what all the abbreviations meant and how to properly set it up. As long as you are using the K-type thermostat that I linked at the top, then setup is very easy.

  • Now my device was already set to Fahrenheit but we will check it anyways.
  • (1) Press SET to enter setting mode;
    (2) Press , and to enter parameters, in this case enter 0086;
    (3) Press SET to confirm;
    (4) Press or to select the new parameter, press until it reads CorF. If it reads 0 then you are in Celsius, if it reads 1 then you are in Fahrenheit.
  • Once that is set up exit back to the display.

Now we will set the temperature parameters.

I will simplify this chicken scratch below, all I had at the time was a sharpie and an air filter.

  • (1) Press SET to enter setting mode;
    (2) Press , and to enter parameters, in this case enter 0001;
    (3) Press SET to confirm;
    (4) Press or to select the new parameter, go to SV (Set Value), set this number to 58°F
  • Setting the parameters for the condenser, follow steps 1-3 then read below
  • Press or to select the new parameter, go to AH2(Absolute High), set this number to 62°F
    • This is the number that the condenser will turn on at, yes it is reverse thinking seeing how the next value AL2 (Absolute Low) is a bigger number.
    • Press or to select the new parameter, go to AL2 (Absolute Low), set this number to 59°F
    • This setup will tell your condenser to turn on at 62°F and turn off at 59°F
  • Setting the parameters for the heat source, follow steps 1-3 then read below
  • Press or to select the new parameter, go to AH1(Absolute High), set this number to 55°F
    • This is the number that the light/heat source will turn on at, yes it is reverse thinking seeing how the next value AL1 (Absolute Low) is a bigger number.
    • Press or to select the new parameter, go to AL1 (Absolute Low), set this number to 57°F
    • This setup will tell your heat source to turn on at 55°F and turn off at 57°F

    This completes my installation and setup of a PID controller to my larder, you can see my original post here.

    Feel free to contact me with any questions or thoughts on how to make the larder more efficient.

The DIY Larder

The larder is a cool room, usually built off of the kitchen where food was stored before the use of refrigeration. Some larders were as big as a standard garage and others could have been as small as a modern-day refrigerator. They were used to store perishable foods and large pieces of meat to help preserve them for a few more days. I have begun to get deeper into the world of charcuterie and have found myself curing meat in a fridge that is barely below 45°F. When curing muscle, the ideal temperature is between 55°F and 60°F, with humidity between 60% and 70%. I have read that wine coolers are ideal but for my purposes, it might be a little small. Aside from curing meat, the box will be the perfect tool for pickling by fermentation, making sauerkraut, and producing many other culinary delicacies.

The equipment that I started with is as follows, and more will be added as the project continues:

Johnson Thermostat – $112

AC Cooling Fan – $25

Humidifier – Cold air humidifier – $30

Dryer vents x3 – $27

Black, White, and Green Wire rolls (16 gauge) – Price varies by length

8 Pin “Ice Cube” Relays with socket x3 x2 of each – $45

Humidity Controller – $80

Humidity Monitor – $12

Surge Protector – $15

Refrigerator – $50 – I used Craigslist

I started this project with a top freezer refrigerator, I am not sure about the cubic footage. After a lot of horrible drawings, and many ideas of how assembly was going to work, I started modifying the refrigerator.

To begin, we remove the doors of the fridge and freezer and started pulling the paneling out from the inside to revel its inner working. As shown below, all of my complicated ideas were simplified by understanding how the unit works, and I couldn’t have ask for a better fridge.

Straight back, above the condenser, is where the fan housing was mounted, which I kept, and the rectangle hole actually vents down to the refrigerator.

The positioning of the fan and the condenser couldn’t have been better. The freezer portion of the box is where I will put a humidifier and a heat lamp to heat and keep a moist environment in the lower box. I took some canned foam sealer and sealed the top vent on the fan housing so all of the heat and moisture will go to the lower box.

Back of the fan housing. I filled the vents with a foam sealer and place a piece of stiff foam on top to prevent the vents from doing their job in the freezer.

After a little more digging we found three screw holes on the left hand side for mounting an ice maker, which again was very convenient. Two of the holes were used for mounting the light socket for heating and the other was used to feed wire through the walls of the fridge. We also unplugged the wiring hole for the ice-cube unit, the yellowish circle in the top right of the freezer in the top picture, and fed the wire through there for the fan.

Next, I drilled a couple of holes in the side, just below the exit hole for the lamp wires, and I installed a thermostat, The thermostat is from Johnson controls and can be found on Amazon. I just used rivets to mount the thermostat, and began deciphering the instructions for what wires went where. Sometimes the instructions can be confusing when it says on temp increase use this and on temp. decrease use this color. First step is to cut the power cable to the length it needs to be to reach the thermostat. Break up the wires and you should have three, mine were two black and one green. The green is your ground wire, and the two blacks are a hot and a neutral. You will need to determine which wire is the hot and which is neutral, the right side of the wall outlet is the hot. Wire nut the grounds, and the neutrals together, you should be left with only hot wires. I will break it down so it is a little easier to understand.

  • There are three connections; Red, blue, yellow, in ascending order.
  • The Red is your HOT this is where your main power will go in.
  • The hot end of your heat light will go onto the yellow screw, this screw will tell the light to turn on when the box is too cold.
  • The hot end of the condenser, coming out of the back of the fridge, will go to the blue screw. This screw tells the condenser to turn on when it gets too hot.
  • The fan is the only item that I do not have connected yet because I need it to turn on in two separate situations but I do not want it running all of the time. I will need to look into a relay of some sorts to get this installed.

Mounted and half wired thermostat.

Once I tested the functionality of the thermostat and the accessories, I began to reassemble the freezer parts.

Functioning light fixture and fan to move the warm and humid air. Next to be put on is the guard for the condenser so it wont cool the upper box, where it should be warm. The yellow foam above the fan prevents cool air from moving into the warming box.


The freezer is now reassembled and the vents have been caulked and secured with 3″ screws with locking nuts. I added the humidifier and ran the wires out the back with the fan wires.

At this point I am waiting on a humidistat and some relays to get the humidifier to work properly; until then I did some wiring organizing and ran the thermostat probe into the main housing of the fridge, where the meat will hang.

A cleaner view of the wiring.

I fed the probe in next to the exhaust fan and placed it on a small shelf about 3/4 of the way down, on the inside of the fridge.

I secured the probe with some plastic wire clips so it doesn’t float around.

After I ran the probe, I wired the exhaust fan into the main power and onto a push button switch so I can clear out the air in the main fridge when necessary. I want to make sure that there is clean and fresh air in the fridge as much as possible without opening the door. I will also install filters and guards on the vents to prevent anything unwanted from getting in and contaminating the food.


In order to get the circulating fan to come on with each of the three components (fridge condenser, heat lamp, and the humidifier) individually I needed to wire them into some relays. I picked up two of the relays at my local wholesale electrical supplier. The 8-pin relays were the closet thing I could find as no one had a single throw relay. There were a few wasted terminals but everything works. To get the fan to work with the humidifier I spliced the hot wire for the fan into the plug for the humidifier, which was plugged into the humidity controller, basically its own relay.

Next I fed all of the wiring for the humidity controller through the fridge, plugged everything in and did a quick test run. The test run proved that everything worked accordingly and the only thing left is to clean up the last few wires, get a surge protector to plug the humidity controller into it, and do a full run to make sure that I do not have things turning on when there is only a degree of difference in the box.

Full side view of the electrical workings and setup.


After doing a test run I realized that I will need a third “ice cube” relay box for the humidifier to turn on properly with the fan. The surge protector is mounted and we are ready to make a second test run for a 24 hour period.


So after a few weeks of crazy work and being sick I got back into the larder. I have realized that the warm air humidifier was not the right choice, during the cooling process the warm air fought against the cold air and was very inefficient. The next change was moving the new cold air humidifier to the lower part of the box. By moving the humidifier to the lower box I have eliminated the use of the last “ice cube” relay box because I do not need the fan to turn on with the humidifier.

The larder is now a lot more efficient and keeps the humidity and temperature very well.

Improvements made on 9/23/2012 CLICK HERE