Air Conditioning Control Unit - CoolBot and ColdSnap

Projects General Guidance
1

Hello

Being a welder for decades I am stepping out of my area of knowledge and request some guidance.

I have a small homestead and need 2 rooms very cold for produce and meat. I found 2 items that will do exactly what I need.

The CoolBot and the ColdSnap. One is $300 and the other is open source and about $30. I like $30 a lot better.

I could use the ColdSnap without help because its already laid out in great detail but I need the buttons and LED display of the CoolBot and dont have $600 to get it.

So, My goal is to basically mimic or clone the CoolBot.

If you are unfamiliar with either product let me explain real fast what they do.

You take a regular window air conditioning unit and attach it to one of the mentioned devices. They maintain a temperature thats below the factory minimum of 60 deg F.

There are 4 wires involved.

  1. Power
  2. Heated diode to fool the A/C units built in air temp sensor to think the air temp is hotter than it is.
  3. Temp sensor to monitor the cooling fins to shut it off near 32F so they dont ice up.
  4. Air temp sensor that tells the headed diode when to turn on and off.

The buttons let you select C or F, set the minimum air temp and turn the power on or off.

The LED lets you see what you are setting and the current air temp.

Its super simple but beyond me. Like I said the ColdSnap does most of this already but you have to reprogram every change and hook it up to see if its right. I need to be able to adjust the settings for the seasons without taking it apart, into the house, and reprogramming.

Also which would be best suited for this project, Arduino or RaspberyPi?

I am not asking for a how to. I am asking for direction so I can teach myself how to do this. I just dont know where to begin.

Any guidance would be lovely.

Thank you,
David

2

Hi,
Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html

Can you post links to the Coolbot and Coldsnap units that you are talking about.

Thanks .. Tom :slight_smile:

3

why not just use the how-to that is on-line ?

http://people.umass.edu/~dac/projects/ColdSnap/ColdSnap.html

we can help you with details as your build progresses.

I will offer that humidity is the killer. when your coils freeze you are done.
if you try to cycle your compressor to fast, you are done.

if you know any HVAC guys, you might be able to hack a much better unit for your walk-in cooler.

with a coil that has wide spacing of fins, you can drop your temp below 32 and not freeze.

super insulation for your floor is needed, as well as walls and ceiling. not hard to do, but a completely sealed vapor barrier is also key to long operation.

4

I should mention that they use a pro-mini.

we prefer to use a UNO for it's ease of use because it has an on-board USB programmer.

the NANO also has an on-board programmer (really just a USB interface)

all three of these use the exact same microchip and all will work exactly the same.

if you want to add remote read outs, extra potentiometers for settings of temperatures. wi-fi to connect to your phone...
we can help you with all of that.
remote alarms, data logging..... all of it.
with any of the chips above.

5

This is an old post, but I just built an updated version of the ColdSnap:

https://forum.arduino.cc/index.php?topic=638054.0