Freezer to Refrigerator Conversion

Introduction

Convert a freezer to a refrigerator, and reduce energy consumption 12x so that your refrigerator uses 8 Watts of average power.

Nearly every household on Earth has a verticaldoor fridge that uses 100W of power on average - or about 2.4 kWh per day. In a country of a few million households, replacing vertical door refrigerators with chestfridges can save enough energy to allow closing down at least one large power station. Alternatively, construction of a new power station to meet the increasing energy demand could be avoided or delayed. http://mtbest.net/chest_fridge.html

In money terms, the Superfridge costs 2 cents per day to run (assuming 10 vent per kWh electricity cost). This is about $7 per year - compared to $88 for an average fridge.

For the Seed Eco-Home, the cost is actually even better. The off-grid energy system cost $3000 for 3kW not including labor. This translates to 2 cents per kWh energy cost over a 20 year life of the PV system. That is about $1.50 electricity cost to run the refrigerator for a whole year!

Original Work

This work is based on the Mt_Best_Freezer_to_Refrigerator_Conversion.

edit

Wiring Diagram

google doc

Wiring Harness

google doc

BOM

sparkfun

• Sparkfun Pro Micro 3V - $19.95 sparkfun - Install Instructions
• 24-280VAC Relay - $9.95sparkfun
  • or SainSmart Relay Module $3.99 - Requires 5V Board
• Thermister $0.75
• 10k Resistor $0.95
• Female Headers
• Jumper Wires M/M
• USB 5V Charger $3.95
• USB Micro Cable $1.95
• Junction Box $7.23
• Twin-screw cable clamp HomeDepot
• Extension Cord - Ace Hardware
• 2 Conductor Speaker Wire - Ace Hardware

amazon

• Sparkfun Pro Micro 3V amazon
  • or adafruit Trinket amazon
• Relay amazon
• Themister amazon $4.32
• 10K resistor amazon
• Female Headers
• Jumper Wires M/M
• USB Wall Charger amazon
• Electrical Junction Box amazon
• 120V Male Receptical amazon
• 120V Female Receptical amazon
• 1-11/16 Hole Saw amazon
• Extension Cord amazon
  • Lighted End Extension Cord amazon
• 2 Conductor Wire amazon

Arduino Code

//A1 read voltage
//D3 sensor power
//D7 relay (+)


  volatile int sensorvalue = 328; //define the variable
  int triggeron = 328;         //number that will trigger fridge on
  int triggeroff = 304;        //number that will trigger fridge off


// the setup function only runs once every time the chip is reset
void setup() {
  digitalWrite(3, HIGH); //for powering thermister  
  digitalWrite(7, LOW);  //for switching relay
  pinMode(3, OUTPUT);    //begin operating pin
  pinMode(7, OUTPUT);    //begin operating pin
  delay(20000);          // wait for thermister to get a good initial reading
}

// the loop function runs over and over again forever
void loop() {
  sensorvalue = analogRead(A1);   //read sensor
if (sensorvalue > triggeron){     //if sensor reads over triggeron, turn on
  digitalWrite(7, HIGH);       //turn on relay
  delay(8000);                 //wait 8 seconds
}
if (triggeroff > sensorvalue){   //if sensor reads below triggeroff, turn off
  digitalWrite(7, LOW);         //turn off relay
  delay(8000);                  //wait 8 seconds
}
}

 

Other Options

• http://mikeysklar.blogspot.com/p/yatc.html
• https://www.amazon.com/gp/product/B0002EAL58
• https://johnlvs2run.wordpress.com/2009/10/08/chest-fridge-conversion/

Further Reading

• Refrigeration
• Open_Source_Peltier_Refrigerator