Wood or pellet stoves are a great way to keep warm during cold days. Unfortunately, they have one significant disadvantage: they can only warm the neighboring air. Warm air rises, of course, and as the heated air moves up, it is replaced by colder air near the floor, which creates circulation in the room where the stove is located. In other words, the heated air collects near the ceiling first, and then seeps down into the lower parts of the room. Unless you’re sitting fairly near to where the stove is, you’re not going to get very warm. Even if you are in the same room, your feet will remain chilly for quite some time!
It follows then, that someone would create a solution to change the way the air circulates, so that the hot air gets more evenly spread through the room, which leads to a much more comfortable environment.
A variety of solutions have been put forth, but in most cases, the power supply became the hindrance. Although the small electric motor used in a log burner fan only require a small amount of energy to operate, standard batteries couldn’t be used because they would be exposed to dangerous levels of heat, in some cases in excess of 300C/570F! That’s definitely well beyond tolerance for most batteries.
Using electricity isn’t a good idea either or you’d have to provide heat shielding for the wiring. If you didn’t, the consequences could be disastrous, and definitely more than customers would be willing to live with. Thanks to refinements in inventions based on 19th century science, however, and vast economies of scale, TEG modules and miniature Stirling engines proved ideal for use in modern stove fans.
Typical fans utilize two separate but interrelated sources:
are the most common source of power for stove fans. TEG stands for Thermoelectric Power Generator,and these modules work by transferring heat from the cooler side of the wood burner fan, to the side that is hotter through electrical conductors. This heat is then converted into thermoelectric energy, and this is known as the Seebeck Effect. The heat from the wood stove is converted to electricity through complimentary conductor pellets which are able to produce their own power. This then makes the motor run, which in turns starts the stove fan in motion. Thermoelectric generators are very reliable and also very safe because they contain no moving parts. They require no other source of power because they generate their own electricity from the heat of the stove.
Their construction is quite simple and so is their mass production: simple, fast and relatively cheap. Most products in this market come from the country that has mastered these kind of production and marketing principals: China. There are just a few European, and one Canadian, brands that stand up to the challenge and survived: Caframo, Sirocco, Valiant or SmartFan.
The second source is really impressive:
works on a cycle that receives its power from a quick heating-cooling alternation related to a certain volume of air.
When the air heats up, the Sterling engine expands, thrusting a piston upward; when the air drops in temperature, the engine contracts, drawing the same piston downward. This rapid succession provides power that transforms the heat energy to mechanical energy used to turn the fan blade.
Both systems involve low-torque motors, which accounts for easy blade control. This means the said blades stop and start according to some pre-designed specification. Most stove fans start when the stove is at a temperature of 65 degrees C. or 150 degrees F.
One should keep in mind some stoves maintain a surface temperature higher than that mentioned above and can damage the internal components of the TEG module. For this reason, the wood burner fan is not likely to work the same in extraordinary circumstances. This is probably the fan’s biggest drawback.
In the end, both of these sources create greater fuel efficiency because they require no electricity or gas to operate, just the heat of the stove. The bottom line here is this: the higher the level of heat, the quicker the blade rotation and expended power. The more heat you want, the faster you get it.
Stove fan equipped with such sophisticated devices could operate using nothing but the heat from the stove, which is great because that means no added fuel costs. Also, these devices don’t need to be charged or recharged. They don’t produce any pollution. They work silently, and pose no health or environmental hazards. Some manufacturers even claim that their products reduce the total cost to operate the stoves, and reduce emissions by burning up to 14% less fuel. That’s the kind of performance that speaks for itself.
The market is dominated by two brands producing this type of stove fans. The production requires high precision, sophisticated machines and are usually hand made thus difficult in mass production. They are usually pricy but in exchange the buyer gets top notch product that not only is efficient but also very impressive to watch them working.
Today, the market is flooded with a variety of fans from several different companies, each sporting a number of different makes and models. They differ from one another in many ways, so finding the “right” unit can be tricky. It can be hard to evaluate them side by side to find the one that meets all your needs. Fortunately, that need not be the case for you! We’ve done all the research for you, and have prepared detailed reviews of every stove fan we present here. We hope our website will be your single source for information, and one stop shop to allow you to make a well informed, confident decision about which one to buy.
Vast majority of the stove fans are powered by the Peltier module pressed between the lower heat sink and the top cooling part to secure sufficient temperature difference. Placement on the stove of those fans is crucial for their performance. Basically the best position for them is at the rear side of a stove and as far away from the flue pipe as possible. This way the cooler air can be drawn through the fan’s fins. This positioning ensures best performance but it doesn’t mean a different placement will cause the fan to stop.
The fan’s performance can be affected by a few other factors specific to the individual heating appliance surroundings, like the depth and shape of the recess, the height of an aperture etc. So, use your fan’s top handle to move it around the top plate of your stove to determine the right position for the best performance – just make sure you keep the fan away from the flue and never in front of it. If you decide to go for any of the SmartFans make sure you get yourself familiar with the illustration below as their positioning rules are slightly different.
Things are much easier with the Stirling powered fans like Vulcan or Warpfire, where there’s no temp difference required – just the heat from the stove. Stirling powered fans are not as vulnerable and withstand much higher temperatures. So if your stove usually gets very hot you might want to consider this kind of fan – especially if you have big area to push the warmth around.
We recommend using a stove or infrared thermometer to control the temp of the stove top and keep it within the best operating range of your fan as well as avoid overheating it.
Soapstone or Gas stoves don’t get their top surface as hot as wood or pellets stoves. Many Heat powered electric fans start working at pretty low temperature like 60 Centigrade which is easily achievable by gas stoves. However those fans’ optimal operating temperature is at top or even beyond the temp range of that kind of stoves. There are a few models though that have their best operation temperature tailored to that range. Check for SmartFan marked with ‘LT’ or Caframo BelAir if your stove’s top doesn’t reach 200 C. Bear in mind to never leave those fans to work on hotter surface as this might damage the Peltier module.
Until quite recently there was no chance any fan could work on inset stoves as they need to stay on a flat pretty horizontal and quite big surface which is usually missing on those kind of heating appliances. But…Hansa, the manufacturer of Sirocco fans has just introduced a new interesting solution that might satisfy owners of built-in stoves – just check the video below for their ingenious solution.