Wood stove for Greenhouse

How do most people heat their greenhouse? Last year I used propane and I can not do it this year. The price of propane has gone up so much that we can not afford it. I want to put in a wood burning stove. Not sure if it should be in or out, what are advantages.
Does anyone have any ideas?
Thanks in advance,

Pam

I have worked with friends that had 100' long houses and woodstoves did not produce enough heat to warm the entire house,, the end farthest from the stove was nearly 20degrees cooler. You could put the cold tolerant plants down there and they would survive, less tolerant plants nearer the warm end etc.....

My greenhouses are only 50 ft long and heat very evenly throughout.

The drawbacks I have are : the stove needs constant supervision if you let it go completely out before loading again, the temperature drops rapidly!!!!
You must have a committed person willing to get up all hours of the night to load the stove, check the damper, (if it gets shut too tight, you smoke the house up and you can imagine.....
Your wood supply must consist of well cured firewood, it burns cleaner with less build up in pipes.
We have 4 houses 20' by 50' and it takes 1 cord of wood a week to keep it going. We live in Maryland and the winters are very cold so the fires are burning allnight every night for 41/2 months.
Our stoves are inside near the back door, so we have easy access to the woodpile. You must have an experienced person set up your stoves, fans, etc... If the pipes are not properly installed through your back wall, with fireproofing around exposed wood you will have problems. Also the smoke pipe really needs to be high in the air for proper draft. We have learned the hard way... We've had fires on the walls from excessive heat build up. Also the metal pipe chimneys stop up faster than a block chimney,, we've lost a greenhouse from a chimney that stopped up in the middle of the night, the pipes inside greenhouse turned cherry red and the plastic sheeting on the walls ignited. So many "exciting" things have occurred throughout our 21 years of "learning" by "doing".
I am thinking of buying one of those stoves that are outside of the building that "say" you load once and it burns for 24 hours! What a blessing that would be. But the cost is considerable. Good Luck,,, Hope to hear what you end up using.

My greenhouse is 30 x 85'
Do you burn wood day and night? I think I could only burn at night, let the sun heat during the day. The winters here are pretty mild.
Thanks for your input.
Below is a pic of greenhouse.

Pam

Hi Pam,
How cold of a winter do you get?

We have a 21x36' (756 sq. ft.) greenhouse with double wall polycarbonate on the ends and top and polyvent on the sides and top vent. Propane costs have forced us to consider wood as a supplement. I bought a small boxwood stove (Vogelzang) at Tractor Supply. It is rated for heating 1000 sq. ft., but with the excessive heat loss I don't expect it to furnish 100% of the heat needed. My goal is to cut propane cost by ~50% which, with doubling in the cost of propane shince last year, we should have about the same cost as last year, which was horrible, but better than paying 2x or more to heat the greenhouse. I'm in the process now of designing the chimney system. I'd like to use single wall stove pipe, but I'm sure the experts will say I need at least double wall. Which would be very expensive. I have questions about what kind of pass through is needed to get throught the polycarbonate, which has a flash point of >450C.

An option that I'm also looking at is a small heat pump. Obviously, to be used for heating not cooling. You can buy small units for $1000-1500. Again, these would not take the place of the propane furnace but would hopefully be more cost effective than propane. The bad part here is that heat pumps are not very efficient at temps below 35F. When I need most of the supplement would be at night when outside temps in TN can occasionally get down to the single digits. The GH stays warm during the sunlight hours, it's just the nights where I need help.

What would be really helpful is some advice on how to compare systems, BYU/hr input or some such compared to heat loss from the GH.

The winters here are proably in the 20's, sometimes colder at night.

Last year was my first winter and I heated with 2 elec oil radiators heaters. Everything was perfect until the temps at night stayed below freezing for longer than an hour or 2. Lose afew things and ended up closing off half the GH. Not sure what I'm going to do this year. I know I'll be putting up more plastic for sure.

I'm using a soapstone woodstove in my greenhouse: it retains heat during nighthours when I run it in the evening hours, so I don't need to do additional burning during the night hours. When it keeps freezing during day hours with overcast weatherconditions, I just need to burn again in the morning before I go to work and it stays warm during day hours too.

Tropical plants looking happy while everything's covered with ice outside

This message was edited Oct 30, 2008 1:50 PM

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're in process of installing a OWB this week and hope to use it for a greenhouse someday. Ours will be able to heat well over 4000sq. ft. and will heat both our home and the greenhouse. The Central Boiler E-classic 2300 high efficiency OWB unit we are getting 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 $$$!

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 message was edited Oct 31, 2008 8:23 AM

Hey Cumulus79 where did your get your soapstone heater? never mind, your in Belgium, I doubt I could "run up the street and get one". Still, GREAT heater
dawn

Hi,

Well, my heater is called 'Altech Eclips'. I have been looking on internet for a long time to compare prices and opinions from other buyers, and it turned out to be one of the best soapstone stoves for its price. While looking on internet I also discovered some stoves from this brand overthere in America, so you surely can get it there too. Maybe you can try to google on it's name. There are also expansions available to add an oven and a storage unit to it (it's a modular one). Keep in mind that a soapstone stove works with radiation, so when you use it in a greenhouse, most of the heat simply radiates outside and dissapears. To avoid that, you must add a reflective panel or coating to the windows near the stove and put as much thermal mass as possible in direct sight of the heater, so it takes up the radiation heat and retains it for many hours. It can be anything from plant pots, containers with water, stone to artwork pieces, tables etc

Thanks, I'll check the net. Great advice too.

This looks also very promising as a heatsource in the greenhouse: http://www.heatstorage.net
Unfortunately it's not yet available in the stores, but maybe it will allow us to do all the expensive heating for free somewhere in the future...

We heat our GH with part of the flu pipe from our woodstove that is in our house, other than that we use no other heat source save the sun in our passive solar GH. It has been used this way since 1983. Works great, but we also have a great deal of stone mass to collect the heat. Picture taken this fall of the heat source. Patti

The other direction. The GH is about 36' long. Patti

If I were to build another house with a GH I would build a larger work area with a wood stove at that end (away from most of the plants) for burning at night, but only if I had a cheap source of wood and in an area that had good passive solar possibilities. Tricky. Patti