The Wood Stove Eco Fan Revisited

A few weeks ago I built a very simple wood stove fan using a couple of computer CPU heat sinks, a TEC wafer, a motor from a CD ROM drive and a home made fan.

At that time I was quite satisfied in how the heat sinks and the TEC were able to provide enough power to drive the motor, however I was just not very satisfied in the design of the fan blade.  The fan spun at a good clip, but it just wasn't moving much air. More of a flaw in the design of the fan blades than anything else.

A week later, inspiration hit at my trip to the Surplus store

The Nerd's Paradise

I actually live a fair distance from any large urban center, so when the significant other says that she would like to do a trip into the city for some shopping, it usually isn't too hard to convince me to come along. 

To me a trip into the city usually means one thing...

A stop at the Surplus Store!

I don't usually have anything particular in mind that I need to get when I go, so I treat the visit as an adventure - you just don't know what you will find. 

Often ideas for potential projects usually pop up during the course of one of these trips (as you'll see in a moment) 

Most time I'll take the opportunity to top up on the essentials for my electronic parts bin such as LED's and perforated circuit boards. Some times I fine odd stuff that is really cheap and mght be useful at some point (for example a large scrolling LED sign for 10 bucks) 

Building a Wood Stove Eco Fan

Towards the end of last winter, the squirrel cage fan in my wood stove gave up the ghost.

Pricing out a replacement fan for my type of wood stove almost made me wonder if they were also tossing in a new stove with the price of the fan. Looking for alternative ideas, I didn't have to go no further than to my parents house.

My parents have heated their home with a couple of wood stoves for many years, with the heat from these stoves being distributed by fans that get their power from the heat generated by the woodstoves themselves. Though much cheaper than the replacement fan for my stove, I felt that even those fans were a bit too pricy for my tastes.

Looking at my parent's fan a bit more closely, I noticed that there seemed to be some sort of magic wafer that was mounted in the middle of the metal framework of the fan. That wafer was wired up to the fan motor and was providing the motor its power. It all looked pretty simple - assuming I could get one of those magic wafers.

A quick search on Instructables and YouTube, gave me the answer, since there are quite a few people on those sites that have built these gadgets. The magic wafer is in fact a  thermoelectric cooling (TEC) module.  These modules work by generating electricity if one side of the wafer is cooler than the other side. In the case of the stove fan, the electricity is generated by having a piece of metal pull heat into one side of the wafer, while a metal heat sink pulls heat away on the other side of the wafer.

A quick look on ebay showed that I could have one of those TEC wafers for less than $3.

An idea began to form....