Thermoelectric Fan Harvests Wood Stove Heat Junkyard Style

Anyone who heats with a wood stove knows that the experience is completely different from typical central heating. It’s not for everyone, though, and it’s certainly not without its trade-offs. One of the chief complaints is getting heat away from the stove and into other areas of the house, and many owners turn on an electric fan to circulate the heated air.

That’s hardly in the green nature of wood heating, though, and fans can be noisy. So something like this heat-powered stove-top fan can come in handy. Such fans, which use Peltier devices to power a small electric motor, are readily available commercially. [bongodrummer] thought that sounded like no fun, though, and created his own mostly from junk. The Peltier module was salvaged from an old travel fridge and mounted to a heat sink from a computer to harvest heat from the stove. The other side of the Peltier needs to have a heat sink to keep it cooler than the hot side, and [bongodrummer] chose an unconventional bit of salvage for the job — the cylinder of a chainsaw engine. The spark plug hole sprouts the mount for the fan motor, and the cooling fins help keep the Peltier cool. And to prevent overheating of the device, he added a surprise — a car cooling system thermostat to physically lift the device off the stove when it gets too hot. Genius!

The video below shows the build, which was not trivial. But we think the end results are worth it, and it reminds us a little of the woodstove generator we featured a while back.

 

26 thoughts on “Thermoelectric Fan Harvests Wood Stove Heat Junkyard Style

  1. These things run on a difference of temperature, so rather than having it be cooled by the hot air at the top of the stove and blow it a few feet horizontally have it suck cold air off the floor or even from the colder spaces in a nearby room. Moving the cold air to warmer spaces does more considering that cold air sinks and stays there.

  2. Tip: I used copper paste as heat sink compound for my stove fan. The stuff you normally use for cpu heatsinks can’t take that kind of heat. It dries out very quickly and then you loose heat transfer between the peltier and the heat sink – peltier solder melts. Also, heat pipe coolers work very well for the cold side…

    1. Congratulations! You have won the award for the most useless blatantly misinformed comment so far in 2018. Would you like to give a speech for all your fans and admirers?

    2. I was going to make the same comment.

      Depending on the country you are in you are likely to have access to lower carbon energy through the electricity grid. Few people in developed countries power their heating systems exclusively from dead wood or industrial offcuts. Cutting down trees to burn them is worse for the environment than leaving the trees standing and using other sources.

      Replanting trees could pay back the carbon debt, but the timescales are so long – many decades – that our environment will take a hit when we can no longer afford it to.

      1. If your sole consideration is firewood you don’t need to wait ‘many decades’ in your rotation. Even the building material and pulpwood industries only wait a handful (3-4) decades with thinning and management every 5-10 years through the rotation. This is also ignoring the centuries old practice of coppicing which almost every hardwood will allow, reducing processing of the wood & allowing more vigorous growth.
        If responsibly harvested peat (200 year rotation) is considered by many to be ‘renewable’, 40 years is certainly deserving of the same title.
        Just because it is more convenient to use gas powered equipment doesn’t mean a person couldn’t use electric or hand powered tools to fell / collect / process all of their heating fuel for a season.

      2. Here in the UK we burn wood pellets in places like Drax power station which used to be coal fired.
        So it’s green right?
        Except that the wood pellets are imported by ship from the USA.
        Louisiana forests are cut down, turned into pellets, loaded onto rail, sent to the port, reloaded into ships, sent to the UK once a day, loaded back on to rail and delivered to the power station.

        Because coal isn’t green enough.

  3. In most developed countries there are laws that require cut down trees to be replanted within a few years or the owner pays heavy fines.

    This means burning wood has zero co2 impact on the environment.

  4. I’ve heated exclusively with wood for four years and I’ve never cut down a living tree to do it. That being said, good forest management means both harvesting and carrying for living forest. Your electric grid runs on oil and coal. Carry on.

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