Difference between revisions of "Milk cooling chest"

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=Milk cooler hack=
 
=Milk cooler hack=
[[thumbnail: File:chestfreezer.jpg]]
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[[File:chestfreezer.jpg|thumb|the freezer we modified]]
  
 
Raw milk needs to be cooled quickly - ideally brought below 40F as quickly as possible (2 hours is a reasonable maximum target) - simply putting milk jars in a refrigerator will not cool it fast enough to maximize safety and longevity of the milk. On top of that, consumer grade refrigerators will often struggle to handle the load of several gallons of warm milk. It can take hours to cool milk this way and the strain that all this puts on the compressor of the fridge will shorten it's life. Plunging milk jars into an ice water bath is best - but that requires making a lot of ice and the extra step of removing the jars and putting them in the fridge after cooling.  
 
Raw milk needs to be cooled quickly - ideally brought below 40F as quickly as possible (2 hours is a reasonable maximum target) - simply putting milk jars in a refrigerator will not cool it fast enough to maximize safety and longevity of the milk. On top of that, consumer grade refrigerators will often struggle to handle the load of several gallons of warm milk. It can take hours to cool milk this way and the strain that all this puts on the compressor of the fridge will shorten it's life. Plunging milk jars into an ice water bath is best - but that requires making a lot of ice and the extra step of removing the jars and putting them in the fridge after cooling.  

Revision as of 17:05, 19 October 2015

Milk cooler hack

the freezer we modified

Raw milk needs to be cooled quickly - ideally brought below 40F as quickly as possible (2 hours is a reasonable maximum target) - simply putting milk jars in a refrigerator will not cool it fast enough to maximize safety and longevity of the milk. On top of that, consumer grade refrigerators will often struggle to handle the load of several gallons of warm milk. It can take hours to cool milk this way and the strain that all this puts on the compressor of the fridge will shorten it's life. Plunging milk jars into an ice water bath is best - but that requires making a lot of ice and the extra step of removing the jars and putting them in the fridge after cooling.

A larger-scale solution is to purchase and install a bulk-tank to cool the milk. A simpler cheaper method that works for up to about 4 -6 cows is a chest freezer modification: the milk cooler hack.

Materials Needed:

  1. chest freezer that can hold water.
  2. silicone caulk
  3. STC-1000 temperature controller or similar cheap knockoff (such as inkbird ITC-1000) with probe. (Manual)
  4. wire to power the unit. (Since unit draws less than 3 watts of power - this wire can be very small. I used 20 gauge but you can check gauge tables and use something even smaller if you have it on hand)
  1. 14 gauge wire or better for switching leg for chest freezer. A piece of an old power chord or a plug wire from a defunct appliance works great.
  1. Wire nuts and/or electrical tape
  1. optional: mounting hardware

procedure

  1. clean and seal all seams under the waterline with silicone
  2. decide where you want to mount the controller on the outside of the chest freezer. Consider the following:
    • accessibility and visibility for checking temperature and changing settings
    • routing wires back to compressor: power, switching and probe wires inside the unit.
    • a location where the unit will not get brushed or knocked off by passers-by
  3. Locate the cooling lines on the inside of the freezer nearest the area where the controls will be mounted - Most chest freezers have radiator coils (the ones that get hot) running horizontally around the inside of the outer wall of the freezer and cooling cools (the ones that get cold) running horizontally against the inside of the inner wall of the chest. To locate the cooling lines - sometimes it helps to plug in the freezer and splash the sides with water. To locate the heating lines place your hand on the outer wall and feel for hot spots. Watch as the water freezes around the cooling lines. If you can't locate the lines you will have to be very careful drilling holes since puncturing a line will release the coolant and destroy the chest freezer.
  4. avoiding the areas where the lines run mark a spot to drill a hole through both sides (inner and outer) of the chest freezer wall.
  5. pick the smallest drill bit that will work to make a hole that the temperature probe will fit through.
  6. Carefully drill through both sides. If you don't know exactly where the lines run, drill VERY carefully just through the wall material and insert a wire to probe around and see if you can locate the lines. Drilling near the top edge is believed to be safer since coils seem to be rarely located there.
  7. Feed the smaller end of the temperature probe through the hole - don't put it in backwards! The exposed wires need to be outside and the sensor bulb needs to be inside and submerged below the water line.
  8. connect the temperature probe to the sensor

Programming the cooler

(See the manual)

settings and default values
Code Function Correct value for farm
TS Temperature Setting 33
DS Difference Setting 1
PT Protect Time (compressor delay) 3
CA Calibration 0
CF Celsius/Fahrenheit C*
  • It's possible to run it in Fahrenheit however since our controller is capable of tenths of degrees centigrade but only whole

Degrees F we will use C.

Key Operating instruction: 1. Check Parameter: In normal working status, press “  ” key once, it will display the setting temperature value; press “  ” key once, it will display the difference value; 2. Parameter Setting: In normal working status, keep pressing “  ” for more than 3s to enter set mode, set indicator lamp is on, screen displays the first menu code “TS”. Press “  ” key or “  ” key to move up or down the menu item and display the menu  code. Press “  ” key to enter the parameter setting of current menu, the parameter value starts to flash. Press “  ” key or “  ” key to adjust the parameter value of current menu. After the set, press “  ” key to exit the parameter setting of current menu, the parameter value stops to flash. User can set the other functions as above steps. In any status, press “  ” key to save the parameter modified value, and return to the normal temperature value. If no operating within 10s,it will exit the menu automaticallyand return to normal temperature display status, and does not save the parameter of this modification. Operating instruction: In normal working status, press and hold “ controller; in Power-off Status, press and hold “ ” key for more than 3s to turn off the ” key for more than 1s to turn on the controller. In normal working status, screen displays the current measuring value, the controller switch modes between heating and cooling automatically. If the measuring temperature ≥ temperature set value + difference set value, the controller starts refrigerating, the cool indicator lamp lights on, and the refrigerating relay is connected. When cool indicator lamp flashes, indicating that the refrigerating device is under compressor delay protecting status. If the measuring temperature ≤ temperature set value, the cool indicator lamp turns off, and the refrigerating relay is disconnected. If the measuring temperature ≤ temperature set value - difference set value, the controller starts heating, the heat indicator lamp lights on, and the heating relay is connected. If the measuring temperature ≥ temperature set value, the heat indicator lamp turns off, and the heating relay is disconnected. Menu Instruction: 1. When the set temperature is degrees Celsius (FCC) Code Function Set range Default Note TS Temperature Set Value -50~99.9 oC 10.0 oC DS Difference Set Value 0.3~15 oC 1.0 oC PT Compressor Delay 0~10 minutes 3munites CA Temperature Calibration Value -15 oC~15 oC 0oC CF Fahrenheit or Celsius Setting C  2. When the set temperature is degrees Fahrenheit (FCF) Code Function Set range Default Note TS Temperature Set Value -50~210 oF 50 oF Min. Unit 1 oF DS Difference Set Value 1~30 oF 3oF PT Compressor Delay 0~10 minutes 3 minutes CA Temperature Calibration Value  -15~15 oF  0oF CF Fahrenheit or Celsius Setting   F Note: When CF value change, all the set values restore to default value. Error Description Sensor Error Alarm: When the temperature sensor circuit is short circuit or open circuit, the controller starts sensor error mode and closes all running status, the buzzer alarm sounds, screen displays ER. Press any keys can cancel buzzer alarm, the system returns to the normal working status after error is cleared. Over-temperature Alarm: When the measuring temperature exceeds the temperature measuring range, the controller starts over-temperature error alarm mode and closes all running status, the buzzer alarm sounds, screen displays HL. Press any keys can cancel buzzer alarm, the system returns to the normal working status after the temperature returns to measuring range.