I have a swamp cooler (evaporative cooler) on my roof

[G+_John Sullivan]

I have a swamp cooler (evaporative cooler) on my roof. Basically it's a water pump and reservoir, which pumps water in a waterfall pattern, and a fan which blows outside air through the waterfall into the house. The moist air makes it feel cooler. (Works better in dry climates than humid ones)

 

Except on really hot days, the cooler works too good. After running awhile, I need to get up and turn the water pump off and just let the fan blow until the house starts to get warm, then get up again and turn the pump back on (etc.)

 

After watching Padre's episode on using an Arduino to open a water valve, I decided I needed something like that.

 

After much experimentation, I ended up with a sensor that sends the house temperature to an Arduino, which turns the water pump on and off as needed.

 

The code is something like: if the temperature is above 80 F, turn pump on. If equal to 79, turn pump on for 3 sec every 30 secs. If equal to 78, turn pump on for 2 secs every 30 secs, if 77 turn pump on for 1 sec every 30 secs and if 76 leave pump off.

 

Works great!

[G+_George R. O'Connor]

I first ran across that tech in Ardmore, Oklahoma. It was 1969. I think you have gone about as fur as you can go having bypassed the bimetallic strip (did you?) and gone straight digital.

[G+_Jeff Gros]

Simple and effective!

[G+_George R. O'Connor]

Jeff Gros you are not aware of my joke. The Broadway Play, Oklahoma! Has a famous line in a song about how “fur” the city folks have gone. I did see my first swamp cooler in Ardmore. I was just joking.

[G+_Jeff Gros]

George R. O'Connor I was talking to John, not George. I was just just praising John's simple yet effective use of arduino code for his algorithm to control the pump. Next time I'll specify who so no one is confused. Sorry! :)

[G+_John Sullivan]

George R. O'Connor Hi George. Thanks for the pun although I didn't get it either until you explained it (having never watched Oklahoma).

Never had the bi-metallic strip thermostat to begin with, just on -off switches for fan and water pump. Pretty primitive, huh?

[G+_George R. O'Connor]

John Sullivan not as fur as it can go. Analog to digital was a black art. I spent a fair amount of time writing 6502 machine code (Woz‘s Sweet 16 made my life much easier) polling 8 bit ports to kind-a-sort-a perform Analog data capture.

 

I love your project. The next iteration is obvious: put that swamp cooler on a chip.

[G+_George Fromtulsa]

As a native-born Okie who has been around awhile, I remember swamp coolers well. There's a lot of man made lakes lakes here now, and that line about "it's hot, but at least it's dry heat" doesn't apply here. Or down in Ardmore, either.

 

In a humid climate, the old swamp cooler would just have everything dripping and growing mold. It would be cooler, mostly because water coming into the cooler from the underground pipes would be cooler than the air. Swamp coolers, in formal attire, are called "evaporative coolers." and they need low enough humidity to "evaporate."

 

You'll see giant ones pre-cooling air for large commercial HVAC units.

 

Friend built a home-made one to pre-cool his outside AC condenser. AC fall came on and tripped a switch to turn on the swamp cooler pump, which gushed water from a plastic kiddie pool onto that kapok swamp cooler fiber he'd put n a cage surrounding the condenser. By dumping the inside condensate water into the pool, he reduced the need for water from the nearby faucet, that was added when a float valve tripped another switch.

 

Ingenious, yet the water around here is often so filled with dissolved lime, even the amount the blew into his unit from the "dripping kapok" started turning it into a marble deposit. He did get a couple of years additional service from the old condenser that was on its last legs anyway. And vinegar would have cleaned out the lime, but not without danger to the condenser's metal.