Free Heating - Well maybe?

I have always paid a lot of attention to how other places heat their greenhouses. It is one of the most expensive or laboring parts of having a greenhouse. Over the years I have seen a lot of different techniques. Most involve boilers furnaces and stoves. Some of the more unique ones were greenhouses at our local city dump using the gas from the decaying trash to heat greenhouses.
One greenhouses was one in eastern Kentucky they had the greenhouse attacked to the side of a mountain once inside the very back wall had a huge fan in it. After talking to the people it seems the greenhouse was up against an old mineing tunnel. During the day the greenhouse would get hot they would pump 55F air out of the tunnel into the greenhouse cooling it off. In the winter the greenhouse would generate heat from the sun and the fan would push that air back into the tunnel. At night the fan was turned off and the warmer stored air would push back into the greenhouse. It was very interesting and seemed to work well. The problem is most people do not have a cave or mine shaft on their land.
More recently their has been talk about using geothermal heating. This is the same heat that was being used from the mine shaft, heat from the earth to keep my plants warm. The problem I have seen with Geothermal is the cost. It cost a lot of money to instal and it can take years to get your investment back. I have been trying to think of more simple easier ways to use geothermal heat with out the costs.

I drew up a simple sketch to show a friend my idea. The idea is to get a large pond lake spring or a well that does not dry up and place a pump in it at a good depth. The water flows through a pipe it should be 2 feet under ground once it is out of the well or pond and traveling to your greenhouse. The pipe then go into a heat exchanger system. I have a few of these they look like a car radiator with a fan that pulls the heat from the water and circulates the cold water out the other end taking all the heat from the water. The pipe coming out should then flow back into the pond or well. It is not recalculated like most geothermal heating systems, it just flow back usually away from the pump to allow it time to heat back up. I have not tested this method but it seems it should work. I am interested to hear what others think of the idea. I have never installed a geothermal heating system so their maybe a bit more to this than what I have shown. If so I am interested to hear more. The thought of not having to heat in the winter sounds great to me. My plants like 55f and to be able to cool the greenhouse down in the summer sounds good to and for it all to be basically free other than electric for the pump and fan on the heat exchanger. Maybe to good to be true?

Very interesting idea,only thing is how long is the air staying at a temp of 55*?
Does the air cool of,trying to reach the back of the greenhouse,and how much does it drop off every 10 ft of travel?
What I can't figure out why my 12 ft greenhouse is 10* cooler up there than chest high below,hot air travels up!
I have fans both up high at the roof and down below chest high,then it's also 10 cooler on the floor.

The Mongolia herders burn the manure from the herds to heat there tents.
Eskimos use whale oil.
Kentucky use to have coal mines,can you buy coal and heat it in some type of heat stove at a affordable price?
I was wondering for myself,being in Kansas,we have lots of wind,if I could figure a way
for windpower hooked to a solar panel,when the sun isn't shining the wind fan would provide the electric need to run a heat source.
Don

I've been looking at the frozen condensation in my new hoop house over the past week trying to figure out a low cost way to control the temps.... let me know when you get a good - and easier than finding a mine shaft! - idea, 'kay?

'Cause I gotta tell you, this double plastic, even blown up, ain't doing a thing.

Sheryl your about the same zone as me. I bought a new greenhouse this late summer this makes the 6th one. I was fortunate enough to find a nice size 200.00 wood buring stove for it. I load it up about 3 to 5 times a day. It's a bit of work but I already have all wood for our larger outdoor furnace.

The idea for the above is that ground water is a constant temprature for us it's about 58f and if you can some how take the heat out of the ground water and pump it back you should be able to heat something at least from freezing.

I looked up this idea on the net. It seems similar system are out their and are being used. Here is a link to one of the better sources I found

http://geoheat.oit.edu/bulletin/bull22-2/art4.pdf


Here is a pic of the new greenhouse. This was a photo before I moved it to our land.

Wow, looks great. I am jealous!

A man in a nearby town who does wholesaling of begonias, mums, pansies, and a variety of vegetables, said that he was using wood heat and described it (this is what I *think* he said) that he took a dog house, put a fan in the doorway, a pipe out of the back of it into the greenhouse and somewhere in the middle of that he burns wood. Said he put in a load before bed at 10 and it was warm enough till dawn.

Can you make heads or tails of that one?

You are right, that does sound like a lot of work. We're getting a wood stove for the house that will (supposedly) burn for 15 hrs straight, with one load of wood. Now, why can't I have something like that for my GH?

In most cases the wood stoves are inside and I use metal flashing on the wall to prevent any fires or melting of the plastic. The stove should be at least 2 feet or more from any plastic. I have a frame around the pipe were it leads out so their is no plastic around it as well. I will have to take a few photos to explain it.

The thing with wood stoves is some wood burns hotter and faster than other wood can be cooler and slower. This also bepends on the amout of air you give it. If your trying to heat a large area you have to produce a lot of heat to keep the temprature up this will mean more wood a faster burning. On the other hand if your just keeping it mild in a small greenhouse you can get buy with a lot slower burn.

Here is a picture of our larger furnace. This can take up around 3 wheel barrow loads of fire wood in one load. It heats up water to 180f and heats 4 large greenhouses. We load it up ever 4 to 7 hours in winter depending on the cold.

We are heating this monster greenhouse with it so it take a lot of heat to keep this greenhouse 65 when it is -5f outside.

Oy - I guess! What are you growing?

I want a garden port like your new greenhouse! I'm very jealous.
I'm up to three greenhouses now, but all are small. One is getting ready to "grow up" soon to a 96 though. I just don't want to think about heat though.

I grow a lot of exotic plants. My main interest is in Aroids such as philodendrons anthuriums Alocasias and Colocasias. I have a bit interest in Bananas and Cannas as well.

Try an outdoor wood-burning boiler unit (OWB). Central boiler OWB's have been around for about 20 years and they have a good reputation with OWB units - check out their website. We installed an OWB in November and hope to use it for a greenhouse someday as well. Ours will be able to heat well over 4000-5000sq. ft. and will heat both our home and the greenhouse with hot water created by the OWB unit that travels via thermopex pipe underground. The Central Boiler E-classic 2300 high efficiency OWB unit we have is a "duel fuel unit" and when/if the wood burns down while you're gone, or out of town, the propane burners ignite to keep things heated until you get back to add more wood. A pretty incredible and a great way to save $$$! After it pays for itself in a couple years you then have - FREE HEAT!

And yes, they do keep things warm in sub-zero temps! The main thing you need is to have several cords (9-11 cords depending upon need) of "seasoned" 10-12 month-old split/cut wood ready to burn BEFORE you get your OWB unit. Or, make sure you have access to several dead fallen trees that will make good available ready-to-burn fuel for the winter at hand. Green wood (from freshly cut trees) does not burn as well and tends to smoke a lot.

This is similar to our unit. Ours is under the name Heatmore. Heats up the water to around 180f and heats the floors of our greenhouse. Our unit is currently heating 4 greenhouses we have to fill it up ofter sense we are heating so much.

The Geothermal GH has been discussed ad nauseum on the GW GH forum.

My neighbor did this with air alone, no heat exchanger, in his wife's art studio. It didn't work. He didn't have enough surface area for exchange of heat/cool exchange in his system.

This version keeps the geothermal concept but keeps the pipe in the GH, IIRC: http://www.sunnyjohn.com/indexpages/shcs.htm The killer ball with this system and all of the air only systems is condensation/mold/mildew.

Lots of people use ground source heat pumps for their homes, so obviously they work, but they are installed in the ground, not in a water source generally.