I'm going to be covering part of my screenhouse with plastic to use as a greenhouse in part of my get out of debt scheme. My problem is that I have no heat source for the greenhouse, so I am thinking of using the chiminea my sisters gave me for my birhtday to heat it. My thoughts are to run a simple up out and up pipe exit with no damper on it. What do you think, would it work? I will also be putting some black spray painted garbage can of water in to help moderate, but they wont be able to keep it warm enough. Any other ideas that won't cost me money? Thanks as always!

-- Doreen (animalwaitress@yahoo.com), December 30, 2001

Answers

I sell lots of chimineas where I work (garden center) and the main thing is to remember to put a good bed of sand in it before you use it. Lots of folks just load it up and start a fire, then the blamed thing cracks from the intense heat. I've never used one to seriously heat an area, most are bought for show. If you could get a good little wood burning stove, you'd be more likely to keep a fire going overnight. The chiminea isn't going to be very heat effecient. But, if it's what you've got, go for it. Just be very careful about sparks coming out the front.

-- melina b. (goatgalmjb1@hotmail.com), December 30, 2001.

What's a chiminea? Sounds like some kind of perrineal!

Is the greenhouse attached to your house? If so, the waste heat out of the house may well keep it warm enough; it works for me here in Orygun. Also, it helps keep the house warmer. Clear plastic is, of course, not much of an insulator.

If you can, make the greenhouse attached to the south wall of the house. if not, make the north side of the greenhouse solid, and insulated. The north side gives you no heat gain except in summer when you don't want it, and plastic (or glass, for that matter) will still lose lots of heat on the north side, even though it's not gaining any.

If you can dig the floor of the greenhouse down so that the plants are at the original ground level, and your feet are thirty or forty inches below grade, you'll make the greenhouse much more efficient too.

-- joj (jump@off.c), December 30, 2001.

I helped a friend devise a greenhouse heater by burying a flue pipe loopback to a distance of 30 feet and 3 feet below ground level to circulate greenhouse air through the chamber by fan to keep the air at about 60 degrees inside the greenhouse. Biggest cost is the expense of burying the 65 feet of flue pipe for the chamber.

-- Jay Blair in N. AL (jayblair678@yahoo.com), December 30, 2001.

Jay, are you talking about essentially a ground source heating arrangement? The soil in my garden is good (that's where the greenhouse will be), but outside of that it's caliche. Caliche is basically rocks and very heavy clay. I'd have to rent a large trencher to do that at $250 per day. It would probably work quite well for someone with either sand or good loam soil!

Joe, a chiminea is a patio fireplace really. It's made out of heavy clay, kind of like an adobe oven. It has a short stack and a rounded bottom and is on a stand of wrought iron. The clay does radiate heat well, albeit fast. I think I will take your advise on closing up the north face! I was having trouble figuring out how to get it to work anyway!!!

I lined the proposed area with black plastic today, thinking that might help with the temperature. Do you think that was a good move? or would I be better off to just go with the ground I have there? I have heavily mulched the area for several years so I could scrape all the mulch off and just have plain ole dirt as the floor. Thoughts on that? Also, the entire structure is covered in black shadecloth, so it does draw more heat through that. I was surprised that it modearted the temperature by about 7 degrees!

I was going to use 1/4 inch hardware cloth to cover the front of the chiminea to stop sparks. I have lots of that around!!

-- Doreen (bisquit@here.com), December 30, 2001.

Doreen, if you use a fire, you will need to have some sort of ventilation. As the fire will eat away the oxygen. Also, you will need to have plenty of humidifiers or water barrels as the dry heat from the fire....well you get it. also, if you could ventilate or pipe the chimney along the full length of your room, then the heat would be better distributed in the room. Oh, and one last thought, you would need a small ceiling fan to move the heat from the top to the bottom. IMHO, Sissy

-- Sissy Sylvester-Barth (iblong2Him@ilovejesus.net), December 30, 2001.

If you have to resort to fire heat, you might consider keeping the fire source outside the greenhouse and using a small loopback to coverge the heat from the source into the structure to avoid the carbon monoxide hazards and moisture depletion potentials.

-- Jay Blair in N. AL (jayblair678@yahoo.com), December 31, 2001.

How many degrees do you need to heat it? If you were to use a small kerosene burner or propane flame, solid fuel or even a good candle in your chimeira it will raise the temperature quite a bit and you would not need to put a flue in. Greenhouses do not need oxygen for the plants, they make oxygen just don't spent too much time in there with the door shut!

Another thing you may wish to try is heating with compost. Hot manure puts out quite a bit of heat and nitrogen that plants love. I am looking for my old solar greenhouse book. When I find it, I can offer more precise information.

I never cared for the idea of wood heat in the green house. Too dry, it causes too much of a tempurature swing to be healthy for most plants and too dirty. Soot blocks light and cloggs the pores of the plants. I do like the chimeira concept. It's kinda like the claypot heaters used in small spaces.

-- Laura (LadybugWrangler@hotmail.com), December 31, 2001.

I think Countryside Archives have a lengthy thread on heating a greenhouse in Texas.

-- Laura (LadybugWrangler@hotmail.com), December 31, 2001.