Temperature differential switch

[steven r]

I think a usefull module would be temperature differential switch. ie. A device that could have 2 temperature sensors and send a signal when one temperature was higher or lower than the other. eg. One sensor could be outside perhaps wireless but a wire out the window could work and the other sensor inside. The module could be use to control a window fan to blow in when it's cooler outside.

It's probally more trouble than its worth but since my AC went out last weekend I've been thinking about options till it gets fixed.