Doug Varney

Here are a few pictures of the RH in the greenhouse. The 55 gal on the top full of water and store heat for the nights. The stove gets its air from a 4" pipe from the outside. I fuel it with pallet wood. I had to develop some techniques to prep wood as pallets no longer come apart. Runs like a rocket.

This sounds like something great. We have an active group here in Underhill called CAP for community Agricultural Program with similar interests. I will be taking pictures of my little greenhouse and meat rabbit enclosure. Let me know if/when/where we can meet.

Doug Varney
Underhill, VT

Update:

I have moved my stove into the greenhouse. The flue is now a 6" metal pipe instead of an 8" chimney. No surprise that I had to shorten the length of my J tube and reduce it's cross sectional area a bit. It now runs quite well. To provide enough residual heat through the cold night, I am going to place a 55 gal drum of water directly on top of the 55 gal drum of the RMH.. I plan on an interface between the two of 20 lb iron weights so that the top of the RMH barrel is in direct contact with the water barrel. I will vent the upper barrel (bien sure) On each side of the RMH I will place two additional water-filled barrels. I will have to see if these side barrels pick up any heat. I might circulate the water among the three IF the upper one gets too hot. Only testing will determine that. I will also include a pipe to the outside of the greenhouse to provide fresh air to the barrel that encloses the wood feed to the J tube. Thanks for the tip about placing a T in the flue pipe to allow for some preheating of the exhaust stack. I will update with more data as the project progresses. Thanks to you for all for the help.

Thomas,

I am currently planning on insulating the floor of the GH with metal roofing to isolate from moisture then 4" of cellulose. The barrels will sit in this with the 6" "flue" along the sides of the barrels. Cob will come later if this doesn't work.

What great information. Thomas, you have convinced me to move my rocket stove into the greenhouse and damn the loss of space. No amount of space compensates for frozen plants. Since my dad was an agronomist, I know about the day/night CO2 give and take. I doubt the greenhouse is quite that tight. That being said, I will run the exhaust back and forth under the plants but I won't be anal about small leaks. Is it important to run the exhaust pipes in a slightly upward direction to encourage draft or does the final vertical stack at the end of the run through the roof provide sufficient draw? You might enjoy the fact that I am reusing #10 steel cans as the pipe for the exhaust. I find that the new aluminum suretape works well to bind them together. I will use conventional stove pipe coming directly out of the barrel but expect the temps to have cooled enough to keep it safe. I also will be running the pipes in between some 55 gallon barrels of water as a heat sink. How important is it to insulate the floor under the exhaust pipes and barrels? I may just do that anyway to be sure. re: the hay. You make an excellent point. I have somewhat encased the bales in heavy plastic. I will check them for moisture as the winter progresses but it gets rather dry here at -15 F.

Ironically my family used to own a farm in VT where it was nothing but heavy blue clay. I may take my pickup truck down there next summer and try to beg some material from some house site. I would love to work some of that beloved ground into the project.

Thanks again for such a fine response to all my beginner's questions.

I think all of your observations ring true to me. My greenhouse is small, was built in the late fall, and is a work in progress. It does have foil faced foam insulation in all non-transparent surfaces and hay bales on the outside as additional insulation. Because it is small, I wanted to use the existing rocket stove in my workshop and try to move in the hot air. I think this current setup is RMH beta. I have a feeling that next summer I will build a heater inside the greenhouse and run the exhaust under the plants with some sort of thermal mass. I have lots of food grade 55 gallon barrels that I may lay on their side and run the exhaust gasses in 6" steel pipes around them as a heat sink. I will want to go through one winter to see how much thermal gain I can get from the sun. Here in VT, November and December are often dark and cold. Jan and Feb can be cold but sunny. I am hoping that the bright sun can carry a good portion of the heating needs. I would love to work with cob but our subsoil here is hard pan and, though impervious to water, may not contain enough clay particles to set up. Looks like I have lots more experimenting to do but that is what I live for.

Thanks for you kind advice. I will keep checking back with you all if more suggestions are made and I will provide some pictures if that would help.

Regards

I have built a rocket stove with cement blocks and firebricks and a 55 gal barrel. It runs like a champ. I am trying to use it as a heat source for my small attached greenhouse. I have two 6" pipes connecting a hot air gathering unit (A 55 gal barrel open in the bottom suspended above the stove). It has a couple of fans to move the hot air to the greenhouse. Right now the exhaust from the rocket stove goes up an existing chimney. The top of the stove barrel get to 700 degrees F which is great. The problem I am trying to solve is how to move more heat to the greenhouse. I live in VT and it is currently 10 degrees and even my kale is shivering. I understand that most rocket stoves move EXHAUST air for heating. I am a little reluctant to do this. Does anyone know what portion of the heat from a rocket stove is released through the barrel vs how much heat is moved through the exhaust? Am I expecting too much?