[jeff5may]

There is interest growing in the General-purpose controller thread, so I have decided I will be using my manifestation in this unit. It consists of an arduino uno development board, an LCD readout with 5-button keypad, and a control board out of a portable air conditioner. I had it working to control the retired window unit conversion in the past, so I am confident it will do what it should. A store-bought relay shield (with its own power supply) would serve the same purpose.

With the other unit, I started out using a non-heat pump thermostat. When it failed, I rigged the homebrew controller up strangely to make the unit happy. It had wires for the compressor, fan, and reversing valve relays coming from the controller. My existing unit had a working defrost board, so the controller did not do defrost. I had the thing working before, and the defost control I was using had a single thermistor as a defrost thermometer. I may end up doing the same thing with my controller.

I haven't had much time to do anything with the unit except prove that the thing actually holds its charge and moves heat. It works in both directions, too. It has been unseasonably warm lately, so I ran it in cooling mode a week or so ago, just to make sure I didn't fry the reversing valve during the re-plumb. My buddy thinks it looks ugly, and doesn't believe it can do a better job than his "infrared" remote control space heater. I already know it does, because it poured out the 95 degree air in his garage, heating it up to around 70 in less than an hour, during a cold spell a couple of weeks ago. I unplugged the beast, and 2 of his toasters could hardly keep up.

I will be running through some ideas for a defrost algorithm that will run off either a single or a pair of thermometer sensors. If I can figure out how to use all 1wire sensors, that would be great. If not, I will have to use up more pins on the controller, which are scarce.