Device to Shut Off Circulating Fan when Stack Temperature Drops???

Does anyone know of a device that would automatically shutoff the circulating fan on your wood stove when the stack temperature gets low? Just curious. I always thought that something like that might be a good idea.

 

You might want something like this.

Emerson 3F05-2 Adjustable Snap Disc Fan Control

There are also fixed temp ones.

 

The only thing is that I would want something that measures the stack temperature and when it gets below a certain value turn off the fan. Another option might be where the fan's speed adjust based on the stack temperature.

 

Thermocouple and a PID controller...$40 worth of parts on ebay. I used a Mypin controller on a previous wood furnace...not much different than what you want to do really...

 

For the big blowers on my NC30 stove I added an adjustable snap disk like pictured above to start and stop the fan whenever a surface (I chose the stove top) hits the desired temperature. Pretty simple in line switch. I like it because the big fans really cool off the firebox which is a bummer when you're trying to get the firebox warm enough for a clean burn and also after the fire goes out I don't want to waste electricity blowing air.

 

So what else would I need to make this work? What other parts?

I also noticed this on Amazon. I haven't totally scrutinized it yet but it appears that this would do what I am looking for. It has a higher temperature range than other units like it and I believe that I can set it to around 230F to cycle the fan on/off. I am going to research more before considering this device.

 

Just watch probe cable temp limits. 250ºC usually means even if you are careful not to let the bulk of the cord get close to anything too hot the first several inches at the probe itself can "dry out"/become inflexible and crumble leaving bare wires. Unless they have some extra insulation at that end, even then it only helps so much. Just something to watch more than anything.

 

Good point about the cabling. I am still shocked that there is something set up for this. Maybe my idea isn't really that necessary?

 

You might save enough electricity $ to pay for the meter/instrument and probe eventually. If there's a watt rating on your fan's UL tag it shouldn't be hard to calculate usage.
Beyond the $ there's also the principle of the thing. There's also the geek/nerd factor.
A snap disk is the cheap and easy/simple way out.