I've done some reading on the thermal powered Eco Fans that run off stove heat. Has anyone used these fans? Do they really move air at the 100 or 150cfm rate as advertised? Does the fan have to be placed on top of the stove, or could I mount it on the horizontal stove pipe exiting the rear of the stove? This would allow for a lower profile install and set the fan behind the stove, but still blow air over the top of the stove. I'm interested in any other pros or cons. Thanks

-- John (eli_john_us@yahoo.com), February 19, 2002

Answers

Good questions, John.

First of all, these fans are GREAT! They are extremely popular here in the north. Now: Do they move 100-150cfm? The only fans I have seen are the Model 800. Is there another model? dunno. The propaganda I have says "generates up to 100 cfm". Well, "up to" encompasses a lot of territory. Besides, how are you going to measure it? A more practical answer is that these puppies really do work. The difference in room comfort is very very large. They're also absolutely silent, and they are always going, without an external source of electricity, as long as the stove is hot. In fact, one thing I've found in using mine (it's been in use 8 months out of each of the past two years) is that it gives me a visual indication of when it's time to stoke the stove - blades slow or stopped.

Can you mount it on the horizontal flue? I suppose so. It does need a flat surface - round stovepipe isn't going to work. Also: the company says NOT to place fan in front of a heat source (such as the vertical member of your flue), but to have it drawing cool air from behind and passing that over a hot surface (ie, the stove top). The temperature of the base needs be 400*F to activate the thermocouple; the company says temperatures over 700*F will damage it. While that sounds like a narrow operating range, I know I've had it running at significantly higher base Ts for long periods of time. At any rate, I have mine placed at a rear corner of the stove, and as I say, it works wonderfully.

Lastly, its cost. Retailers in Alaska sell it for around $95-99. The fan is made in Canada, and I've picked up a hal dozen there for about C$85 or so. With a 1.4:1 exchange rate, it makes them far less expensive than here. Nevertheless, they are not cheap, and I wonder how cost-effective they are for an area where you're running a woodstove for less than 24hrs/day 6 months/year (I run mine 8 months), and where you pay less than the 40 cents/kWh that I have to cough up. I have some addresses for the manufacturer, Caframo Ltd. www.caframo.com caframo@caframo.com 800 567-3556 519 534 1080 Caframo Ltd. R.R.2 Warton, Ontario NOH 2TO

Hope this helps!

-- Audie (paxtours@alaska.net), February 19, 2002.

A few more data on the fan:

They're 5 1/2" wide by 4 3/4" deep by 8 1/8" high - fairly small.

Also meant to say that 100cfm isn't really a whole lot of air. It's a cube 4.6' on a side. Nevertheless, the fans work!

-- Audie (paxtours@alaska.net), February 19, 2002.

The basis upon which these eco fans run is interesting, and this information may provide anyone interested with another way to look at or use thermoelectric convertors.

1821 Thomas Seebeck found that an electric current would flow continuously in a closed circuit made up of two dissimilar metals if the junctions of the metals were maintained at two different temperatures (Seedbeck Effect). There have been generators made by the Russians that use this process to produce enough current from the heaters to power a transistor radio.

If you are interested in this interesting effect then you might want to look at Bath water runs TV, http://www.globaltechnoscan.com/31jan-6feb/generators.htm, Professor Michael Rowe showed that the amount of heat contained in the water left after a bath was sufficient to provide the electricity needed to power a color television set for an hour.

-- BC (desertdweller44@yahoo.com), February 19, 2002.

Have used one this winter with our wood stove, along with one of those little 5 inches square fans mounted up in a corner of a doorway, and it is the first year we have felt comfortable in the north end of our house. It really does work, without the use of electricity, so great if your power is out. My sister has one, and has even used it on top of her wall propane heater. They look pretty simple, and if you were mechanically inclined, you could probably whip something like it up. Jan

-- Jan in Co (Janice12@aol.com), February 19, 2002.

I don't know if this is something you would be interested in but due to the expense of the commercial stove blowers my husband designed and made his own. We have a Regency woodstove with a sort of extra steel plate that goes up the back of the stove with an airspace of an inch or two between the back of the stove and the plate. He got furnace duct and bought an in-line blower for 6" ductwork and bolted this to the bottom of the back plate, he added a switch and we were in business. It dramatically increases the heat distribution in the house. Of course, when the electric is off it doesn't work. Total cost was less than 30 dollars. It does get a little noisy, esp. when turned up high. This may not work if you have a more basic type stove, but perhaps you could adapt something using the materials to

-- K.G. (grable@penn.com), February 20, 2002.

Wasn't familiar with these but did get a magic heat electric unit installed in the pipe. I know it won't work without electricity but sure does a great job of circulating the heat. gail

-- gail missouri ozarks (gef@getgoin.net), February 20, 2002.