I built a PICAXE-based fan controller for an A/V cabinet in September 2006 to keep the then-new 26" LCD TV cool. I had the project on one of my websites and it was featured by Hacked Gadgets in 2007
I must use this principle for a future project for my daughter's bathroom. If the hot water pipe remains hot for more than xx minutes, an alarm will sound and not stop until the pipe cools down.Running 24/7. I have a 08M and a 18B20 temp sensor attached to the shower hot water supply pipe (in the water heater cupboard) running a bathroom extractor fan since 2002. Its now in it second home.
Monitors the water temperature until it drops to certain temperature (then assumes the shower has stopped) then running the fan for 20 minutes.