Hello I found these project online its called vent a garage. It has 2 ac fans the LINK DEPOT 120mm AC Cooling Fan (AC-FAN-1238B) and its controlled by a thermostate. What I have plan is to use the arduino and a temperature sensor to turn on the fans when for example reaches 70 degrees. what I dont know is what to use to link the 2 ac fans to the arduino to communicate.
these are the spark fun instructions
https://www.sparkfun.com/tutorials/119
But I do agree, If your not familiar and comfortable working with mains voltages, GET HELP, knowledgeable help, professional help if needed. 
THIS CAN KILL YOU IF NOT DONE RIGHT 
You get to do things right as long as you do them right, in many cases you get to do things wrong only once...
Peter
As I said in the PM, having the link in place helps others if they follow it, and given the warning I provided could be made safe.
In many cases the person is ignorant because they don't know, so understanding the reasons and things to look for is part of learning.
I'm less worried about people playing with mains voltages and killing themselves, than I am for them to leave a death trap for someone else.
Most electrocutions aren't because someone intentionally touched the mains, its the un-intentional contact that causes problems. 
Besides the electricity being able to kill you, the force of the shock can cause physical injuries as you are thrown across the room, or off the ladder, etc.
RCD's do provide some help in removing the power (after you've gotten the shock), but not all circuits are required to have them, so treating all mains as deadly is far better.
Bernardo
Is there a reason why you can't just add a manual thermostat set at 70 deg to turn the fans ON.
I applaud you wanting to learn, but I suggest using the arduino to measure the temperature and maybe warn you.
You could follow this article we did to give you a high and low setting (sorry we used celcius)
http://www.theshedmag.co.nz/online/images/stories/downloads/arduino/arduino-101-part4.pdf
The sketches are just to the right, and the LCD isn't required if you don't want it.
Mark
Peter
As I said in the PM, having the link in place helps others if they follow it, and given the warning I provided could be made safe.
In many cases the person is ignorant because they don't know, so understanding the reasons and things to look for is part of learning.
I'm less worried about people playing with mains voltages and killing themselves, than I am for them to leave a death trap for someone else.
Most electrocutions aren't because someone intentionally touched the mains, its the un-intentional contact that causes problems.
Besides the electricity being able to kill you, the force of the shock can cause physical injuries as you are thrown across the room, or off the ladder, etc.
RCD's do provide some help in removing the power (after you've gotten the shock), but not all circuits are required to have them, so treating all mains as deadly is far better.
Bernardo
Is there a reason why you can't just add a manual thermostat set at 70 deg to turn the fans ON.
I applaud you wanting to learn, but I suggest using the arduino to measure the temperature and maybe warn you.
You could follow this article we did to give you a high and low setting (sorry we used celcius)
http://www.theshedmag.co.nz/online/images/stories/downloads/arduino/arduino-101-part4.pdf
The sketches are just to the right, and the LCD isn't required if you don't want it.
Mark
