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Discussion Starter #1
So I am building a greenhouse on the side of my house, and will be putting a wood furnace to heat the house there. For the chimney I will be using a 6" pipe that has 1/2" thick sidewalls and will be 6' taller than the roof of the greenhouse. It will be anchored to a concrete pad, and should be pretty strong.

I have been contemplating adding something like a windmill to the chimney which will drive a shaft back down to the greenhouse and run a squirrel cage fan. On the coldest days here it is often windy, so in theory that wind will atleast help to blow the hot air into the house.

The furnace will be controlled by a thermostat in the house, and if the main electric blower kicks on I plan on having a simple one way gateway plumbed in that will shut off airflow from reversing out the wind driven blower. The two blower systems will be independent, I already have the fans, just need to decide what the best way to drive the wind powered blower would be.

Has anyone done something like this? What would be the best design for harnessing the wind, a small windmill style fan blade? Or maybe a vertical style? What would be the simplest way of protecting the windmill from high winds? Not looking to spend a fortune, prefer to build everything myself if possible.
 

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I would consider using some type of clutch (possibly centrifugal type or over run type so one could run the fan via electric motor if needed,


for a speed control I would consider some type of system that would either make a brake like the old wind chargers, or a spring loaded system that would let the blades flex back to the point the shed the wind,
or a system like the Aermotor water pumping wind mill that is off set some so the wind blows it out of the wind,
 

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I think I'd use the turbine to generate electricity and use that to power your fan. Just me. Other poster is correct, its easiest turn the vane on an inclined plane (further it climbs the inclined plane the more towards the wind it points) to turn rotor into wind in extreme weather to protect your setup.

Sounds like an interesting project, keep us posted!!!
 

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Google "brake drum windmill"

Otherpower.com is one of best sources for info on DIY windgennies.

I think your underestimating what it takes to hold a windmill up. You have both the force of the wind trying to blow it over and the vibration of the blades trying to tear everything apart. I would not hook it up to a chimney. It would tear apart all joints in the stoverpipe that could lead to leakage inside the green house. Sounds like a nice way to gas yourself out of there.

WWW
 
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Discussion Starter #5
I will be running a dual setup, one conventional blower and one wind powered. Seems the easiest to setup and maintain and I have the parts except for the actual windmill. I figure on a windy day the conventional blower will never have to come on.

I don't want to use a generator as a direct drive seems like it would be cheaper and easier to maintain. A wind generator may come later, but I want this project to be mechanical. If you are already setup for such a generator may be a better route.

I don't think I am underestimating the stress the chimney will receive. I am building it out of a piece of 6" internal dimension pipe. It has 1/2" thick sidewalls, 7" outer diameter. You could mount a VW to the top and it could support it. The base is a concrete slab with a concrete block base for the chimney all reinforced with rebar.

The style of wind blade and a system to keep it from spinning itself apart are the main problems I have not figured which way is the best route. A spring loaded brake that will engage at a certain speed seems viable as well as the old system of turning the blades out of the wind. Would a vertical Axis windmill even need a system to slow it?
 

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WWW said; Otherpower.com is one of best sources for info on DIY windgennies.

I think they have changed their web site to a for profit. I don't find their plans on how to construct homemade wind turbines anymore. You can buy that info on CDs or books now.
 

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Completely off the original intent but still on topic.

First thing I want to point out is 1 sq' of Green house will Heat will heat 3 sq' of the other building.

If you Build it right , that is Glazing on the South side, North conventional and insulated. It will be be less heat load.
I would also Incorporate heat mass into along the North wall and Floor.

That heat I would use a air handler to move into the house through your existing duct work, via a cooling thermostat in the Green house.

Now for the Wood stove, you make a brick surround around it, that is more for the benefit of the Green house.
Put a water coil in the stove, and a coil around your smokestack, you would need a small length of single wall before your twin wall.
that then thermo siphons to a tank, number of ways to go there.
that then feeds to a A coil in your air handler via a boiler pump.

Now inside you have a thermostat for the air handler, but only for heat.
When it calls for heat it kicks on the air handler and boiler pump.

You should also have a cold air return from the far side of the house to the far side of the green house.

The biggest expense with heat is the fuel, the electricity to move the heats not a biggie. At least to me.

We have a well designed and well built house, on a sunny day in mid winter it will hit 65 with no heat,just solar gain.

Have yet to turn on the furnace, we have been using the stove though been a cold, cold November.
We have been using the stove but only to bring the temp up to 70.
A arm load of wood does that.
Actually had it at 80 last night around 9, we have yet to get any solar gain today and its still 65 in here.

If I could talk the GF into an Atrium on the front, with thermal mass, I would be able to really cut any wood use.
 
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