Geothermal Heating

[Michael Quinones]

Is anyone using geothermal heat to heat a green house.  For example pumping air threw a pipe burried in a trench 200' feet long 6' down?   Or pumping well water trew a hose under the stock tank? 

Maybe I should have asked the question before I burried the pipe Hmmmmm.

We are in Gainesville, North Florida I do understand the warmest the air comming out of the ground in this are will be about seventy degrees but at least we can capture that heat being cost effective.

 

[Kou]

You're amazing!!

How much do you charge for building the Rocket Mass Heater?

[Japan Aquaponics - アクアポニックス 日本]

I am really sorry - I have been searching around and I just cannot find the source... but there was a guy who did exactly this... he built a rocket stove into his aquaponics greenhouse and had the thermal mass under the grow beds.

One thing to note - is there any specific reason for heating the greenhouse instead of the water?  I am not 100% sure, but isn't heating the ambient temperature the most inefficient way of heating the water? (Assuming it is the water that actually needs to be heated to stop it freezing).

I had also heard that plant roots need a warmer temperature, but that the leaves are more tolerant - so in this case might it be more efficient to warm the water as sustainably as possible, rather than the air, or a solid thermal mass?  In effect, use the water as your thermal mass?  Perhaps use the rocket stove to raise the water temp?

[Vlad Jovanovic]

Have you thought of maybe some sort of PLC, temp sensors, relay, and a small motor to open and close the exhaust?

John Wroten said:

Yes Michael. The air coming through the  underground pipes now is 60 (give or take a degree). The man that I read from, that designs these systems give the computations for the fan needed to circulate the air. As it turns out, his comps say a small 12 volt, 4 watt fan made to cool a computer will work. I bought 2. I put one on the intake end, and one on the exhaust end. After a month of this, I decided this was not enough. I put a small 110 volt 8 inch fan on the exhaust end and cut a hole at the very peak of my roof and placed the unused 12 volt fan to blow hot air out on hot days. I attached a 4 inch flexable hose to the intake fan, and ran the end of it to the peak of the greenhouse. I can see a small degree of heat rise in the air coming from underground.

The designer said to use dirt as a back fill on top of the sewer pipe, but me being a "rocketscientist" decided to use rock. I put 6 inchs of rock on the pipe, then 6 inches of dirt ( gravel has gotten very expensive), another run of pipe, then 6 inches of rock, and so on until I covered it all with small gravel as a floor.

The designer said the in the heat of the summer, the underground cooling would not be enough. You would still have to have help. I entend to place a 21 inch exhaust fan in the peak, and I have a 4 foot window on the oppisite end of the greenhouse to open.

My biggest chalenge now is how to automaticly open an exhaust port when I am not around. Those solar powered openers, open at 70 degrees. I need something that would open at a much higher temp. I could sure use some help on this. Anyone. Thanks....John

Michael Quinones said:

John I had the same concern about creating more heat in the green house in the summer but the temperature undergroung remains fairly costant.  In the winter we can raise the temperature with the air comming from the underground circulation but in the summer we should be able to cool the green house becase the air comming out of the underground pipes should be cooler than the air in the gren house.  Air moving threw a pipe for 200 feet I think has to aclimate to the underground temperature.

[Rob Torcellini]

I jsut put a rocket mass heater in my greenhouse:  http://youtu.be/_DhCRUMxnNM  It's working quite nicely so far!

To answer the earlier question about heating the water instead of the air.  You can heat the water to about the same temperature as the air.  If you rely on all the heat for your greenhouse from the water, you will run into big problems.  With the air being cooler, the water will condense on everything and keep your humidity near 100%.  I had ice forming on all my polcarbonate...even froze the door closed so I couldn't get inside!

[John Wroten]

Rob, I just watched your video on your rocket stove. It is outstanding. I wish you were my neighbor, but since I know that wont happen, then I can wish I saw your video before I built my greenhouse. If I were but 15 years younger, I would start all over, and try to duplicate your installation.

Again thanks Rob. You are quite the engineer.....John

Rob Torcellini said:

I jsut put a rocket mass heater in my greenhouse:  http://youtu.be/_DhCRUMxnNM  It's working quite nicely so far!

To answer the earlier question about heating the water instead of the air.  You can heat the water to about the same temperature as the air.  If you rely on all the heat for your greenhouse from the water, you will run into big problems.  With the air being cooler, the water will condense on everything and keep your humidity near 100%.  I had ice forming on all my polcarbonate...even froze the door closed so I couldn't get inside!

[John Wroten]

Vlad, I have thought about this. I have an old 12 volt actuater arm off a 10 foot satellite dish. Yesterday I found the power supply for it, with the forward and reverse buttons, but this rocketscientist hasn't figured how to incorporate a temp sensor into the  equation yet. This is what I need to open and close a vent door. .John

Vlad Jovanovic said:

Have you thought of maybe some sort of PLC, temp sensors, relay, and a small motor to open and close the exhaust?

John Wroten said:

Yes Michael. The air coming through the  underground pipes now is 60 (give or take a degree). The man that I read from, that designs these systems give the computations for the fan needed to circulate the air. As it turns out, his comps say a small 12 volt, 4 watt fan made to cool a computer will work. I bought 2. I put one on the intake end, and one on the exhaust end. After a month of this, I decided this was not enough. I put a small 110 volt 8 inch fan on the exhaust end and cut a hole at the very peak of my roof and placed the unused 12 volt fan to blow hot air out on hot days. I attached a 4 inch flexable hose to the intake fan, and ran the end of it to the peak of the greenhouse. I can see a small degree of heat rise in the air coming from underground.

The designer said to use dirt as a back fill on top of the sewer pipe, but me being a "rocketscientist" decided to use rock. I put 6 inchs of rock on the pipe, then 6 inches of dirt ( gravel has gotten very expensive), another run of pipe, then 6 inches of rock, and so on until I covered it all with small gravel as a floor.

The designer said the in the heat of the summer, the underground cooling would not be enough. You would still have to have help. I entend to place a 21 inch exhaust fan in the peak, and I have a 4 foot window on the oppisite end of the greenhouse to open.

My biggest chalenge now is how to automaticly open an exhaust port when I am not around. Those solar powered openers, open at 70 degrees. I need something that would open at a much higher temp. I could sure use some help on this. Anyone. Thanks....John

Michael Quinones said:

John I had the same concern about creating more heat in the green house in the summer but the temperature undergroung remains fairly costant.  In the winter we can raise the temperature with the air comming from the underground circulation but in the summer we should be able to cool the green house becase the air comming out of the underground pipes should be cooler than the air in the gren house.  Air moving threw a pipe for 200 feet I think has to aclimate to the underground temperature.

[John Wroten]

I really dont know. I bought Sylvia's book, but I didn't get the temps needed for the water in the grow beds. Im sure it would have to be different for the summer crops and the winter crops. Right now I am holding between 67 and 72. Nothing is dying, but the lettuce isn't doing as great as it did when the water was cooler. My better half bought some "end of season" starter pots at Lowes. It included tomatoes seeds, so she wanted to grow them in my greenhouse. I let her start them in a pot full of potting soil. She did and when she wasn't looking, I placed one of the growing plants in my water. It is growing twice as fast as her plants. I do water her plants with my fish poop water. It seems I learn something new everyday...John

Japan Aquaponics - アクアポニックス 日本 said:

I am really sorry - I have been searching around and I just cannot find the source... but there was a guy who did exactly this... he built a rocket stove into his aquaponics greenhouse and had the thermal mass under the grow beds.

One thing to note - is there any specific reason for heating the greenhouse instead of the water?  I am not 100% sure, but isn't heating the ambient temperature the most inefficient way of heating the water? (Assuming it is the water that actually needs to be heated to stop it freezing).

I had also heard that plant roots need a warmer temperature, but that the leaves are more tolerant - so in this case might it be more efficient to warm the water as sustainably as possible, rather than the air, or a solid thermal mass?  In effect, use the water as your thermal mass?  Perhaps use the rocket stove to raise the water temp?

[John Wroten]

Kou. Rob lives in Conn. Get in your car. stop in Ky to get me, and we can drive to Conn to visit Rob. We can take our cameras...John

Kou said:

You're amazing!!

How much do you charge for building the Rocket Mass Heater?

[Vlad Jovanovic]

John, this is an Arduino UNO ($28.00USD I think) and a DHT11 temp sensor ($2.50 or $3.50 I can't recall) and a run of the mill bread board for testing out circuits...My relays (not pictured were real cheap too). I have absolutely no experience in physical computing, and no knowledge of any of the C languages (C, C+, C++,C# et. al). But within the first day (and well into the night hehe) I was able to get temp and humidity readings, and turn a mains power, lamp and a small motor on and off with the help of a relay...

The wiring up is pretty str8 forward (you'll need some resistors from Radio Shack or wherever, should be under a dollar)...the programming (for me) is the hardest part. Though luckily for us Arduino is an open source platform, and there is an automation group here on this site that might be willing to help you out with the programming part of it. There are also tons of people on the net sharing their projects and 'programming libraries'. There are also good tutorials on-line to help you out with the basics.

You should be able to, when a given temp (determined by you) is reached by the sensor, to actuate the 'forward' button through your relay, same with 'reverse' at a value you input. DC is going to be a bit different from AC so make sure you keep that in mind. (Turning things on DC is no problem, turning them off properly needs to be given special consideration as there is no "zero crossing point" like with AC, and you could fuse your relay together after some time due to the electric arc, but this too is 'easily' remedied. IDK might be worth a try...

[John Wroten]

I have thought of an ordanary thermost. The actuartor arm has limiting switches in it, so I can leave the power on each way it runs. If I can set the thermostat to close a relay to provide DC curent one way to open the vent, and when the air temp gets cool, then the thernostat closes another relay that would reverse the DC to close the vent. Just a thought, but not on the drawing board yet. I'm still just opening and closing the door for cooling now. I am busy trying to get a couple of IBC totes ready and set up for the coming spring planting in my basment.

Thanks Vlad. ...John
Vlad Jovanovic said:

John, this is an Arduino UNO ($28.00USD I think) and a DHT11 temp sensor ($2.50 or $3.50 I can't recall) and a run of the mill bread board for testing out circuits...My relays (not pictured were real cheap too). I have absolutely no experience in physical computing, and no knowledge of any of the C languages (C, C+, C++,C# et. al). But within the first day (and well into the night hehe) I was able to get temp and humidity readings, and turn a mains power, lamp and a small motor on and off with the help of a relay...

The wiring up is pretty str8 forward (you'll need some resistors from Radio Shack or wherever, should be under a dollar)...the programming (for me) is the hardest part. Though luckily for us Arduino is an open source platform, and there is an automation group here on this site that might be willing to help you out with the programming part of it. There are also tons of people on the net sharing their projects and 'programming libraries'. There are also good tutorials on-line to help you out with the basics.

You should be able to, when a given temp (determined by you) is reached by the sensor, to actuate the 'forward' button through your relay, same with 'reverse' at a value you input. DC is going to be a bit different from AC so make sure you keep that in mind. (Turning things on DC is no problem, turning them off properly needs to be given special consideration as there is no "zero crossing point" like with AC, and you could fuse your relay together after some time due to the electric arc, but this too is 'easily' remedied. IDK might be worth a try...

[Jon Parr]

Rob, great video. I just finished a rocket heater for my room as well. I built my combustion chamber from an 8" 90 deg duct inside an open-topped barrel, right-side up, then filled the bottom of the barrel with mortar and fire clay. Though it wasn't my intention, it is portable. The exit duct is cut in the side if the barrel, about 6" off the floor. I then put a closed top barrel on top of the first, with a barrel clamp exactly like you did, and I use the upper barrel to heat fish tank water. The exhaust duct is 6" single wall furnace pipe, and I will run it horizontally for about 20' thru my greenhouse, surrounded by a 10" pipe with a fan forcing room air between the 6" and the 10" pipe counterflow to the smoke. I don't have any thermal mass, other than the water, and I'm bummed about that. I would have prefered to bury the pipe under the floor as you have done, but the floor is existing concrete, and I'm lazy.

Nice job. I'm also building a second greenhouse, and opted to heat using a wood gasifier. There are two 4" flexible ducts cast into the concrete. One is to cool the syngas on the way to the generator, and the other is to cool the engine exhaust before exiting the slab, harvesting heat both ways, and supplying electricity for growlights (and my entire house and probably feed the grid, too)

I'll get some pictures posted. I hate paying for electricity.

Also, I intend to exhaust both the rocket heater and the generator near an air intake, to provide a CO2 boost back into the GH

[Jon Parr]

I have less than $100 in my rocket heater, and built it in one evening.
The most expense was 5 sacks of mortar and a half sac of fireclay. The barrels, most of the furnace ducting, and a short length of triple wall stove pipe (for the interior chimney), were all scrounged.

Kou said:

You're amazing!!

How much do you charge for building the Rocket Mass Heater?