Good article on heating a greenhouse,, check it out : )

Harnessing the Value of the Heat

Is the winter cold digging in to your heating costs? Are you searching to harness the power of the sun to cut cots in your greenhouse? Here are a few ideas that you can make work for you, where you might be able cut costs, and maybe even cut out heating your greenhouse at all during certain times of the winter months!



Use water barrels. Getting large barrels and painting them black so they can absorb the sun, and hold the heat until the cold of night arrives. When the nighttime arrives, the thermal heat that is being stored in the water barrels is slowly released into the air of the greenhouse and this helps to keep your heat bills lower. You can use any kind of barrels plastic or metal and just paint them black. Fill with water and that is it! One extra thing you might like to do is to keep a screen over the tops of the barrels so that water bugs and mosquitoes cannot lay eggs in the water. For best effects use buckets or containers with lids so that the evaporation of the water does not cause you to loose the stored heat as fast. If you have lids that are not air tight you can duct tape the lids close to keep the heat in the barrels.



If you are still in the purchasing and the building stage of your hobby greenhouse you are in luck! You can correctly calculate and place your greenhouse to where it will receive the most benefit of the sun over the winter months for heat and thermal storage use. When you gauge where your greenhouse will receive the most amount of sun you will find that you can save on heating costs compared to other parts of the yard.



If you are looking to get some five-gallon buckets you can easily inquire with bakeries, delis, caterers or construction companies to get some for free. Many times they are glad to give them away and not to have to store them. You can even use smaller ones (from milk and tea or juice from your home) and fill them with water and place them nearest your most fragile plants to keep them ?warmer? during the coldest months. The bigger the container that you use, the slower the heat release will be back into the greenhouse. When you use large fifty gallon drums the heat release into the greenhouse will be much slower than with five gallon buckets.



While you might think this is strange, there are even gardeners who have their greenhouse very close to their home. So close in fact that they run a hose from their dryer in to the greenhouse. This gives the plants both moisture and heat during times when heat is valuable in the winter months. This is easiest when the greenhouse is attached to the home, but is can be done when the greenhouse is even up to 50 fifty feet away from the home! If you are able, and don?t laugh about it, you can place a blanket over the top of the greenhouse at night to prevent even more heat from leaving the greenhouse and to keep your heat bills even lower. Heating a greenhouse does not cost very much at all, but when you can heat the greenhouse for almost free ? it is worth the try!

Thanks for the great information, I am in the contraction stage of my gh and was wondering those very things..As far as the 5 gal. buckets, I thought they would be too small and glad to hear they are not since I have a ton of them at school. I like the dryer idea since I am building mine right next to the house and not far from the dryer.

Thanks again.
Vickie

Great information...thanks

Glad it was of some advice,, We built ours this summer and double wrapped it with bubble wrap. I have been thinking of how I can keep it above freezing,, I did some research and found this article. Hubby brought me some grey buckets home from work which I am going to paint. I know it will take some long sunny days to heat the water and hope we get some to . If it does work out I will keep using them but if not I am going to have to think of other options.
Enjoy.
vicki

I have been successfully growing spring bedding plants and hanging baskets in a 10X20 greenhouse which I designed and built 27 years ago in the Denver area. It is principally solar heated. Heat storage consists of 600 water-filled 1-gallon milk bottles. They are stored on floor to ceiling shelving 2X20 along the inside north wall. Shelf spacing matches the height of single bottles, as these bottles are so thin that they will leak if stacked on top of each other. To conserve heat, only the south wall and 60% of the roof area are glazed. The remaining roof surface and north east and west walls have insulating batting in the 2X4 framing (Denver has about 300 sunny days per year, so the plants get plenty of IR for healthy growth). When the temperature gets below 0 for more than one night, I turn on 2 250-watt IR lamps. This has been sufficient to prevent freezing throughout the life of the greenhouse. Note that temperatures near freezing are very hard on early plantings of tender plants such as begonias. Very sensitive plants such as orchids are completely out of the question. I do grow a wide variety of perrenial and annual flowering and vegetable garden bedding plants with very little problem. Cooling the greenhouse in our dry climate requires evaporative cooling at a rate of about two air changes per minute (about 3500 cfm in my 10X20 greenhouse).
Note that IR oxidizes the plastic bottles over time. IR exposure varies with positioning on the shelves, so I replace them when they start leaking. Average life of each bottle is probably about 8 years. Therefore, about 75 per year are replaced.

I have a lot of black 5 gal. buckets, do you just fill them up with cold water and set them in the GH. Or do you have to fill them up first with hot water? What if the water doesn't get hot. I know my GH gets in the 70's to the low 80's in the day. Is that enough to heat the water in the buckets?

Here is another suggestion.

I have my GH on the south side of my house about 2 ft. away. My husband ran a vent from our house heater to the GH. This really helps out. At night I make sure the house doesn't get below 62*. You have to heat your house you may as well have a little bit of that heat going to your GH. I know it won't take care of it completely so I have a electric heater in the GH. I keep it set on the frost setting. So far we have had nights down to 28* and the flowers in the GH are doing fine. You will be able to see how close the GH is to our house. By putting it there our house blocks the north wind.

I think the water would heat up just fine..esp in black containers. I was wondering if anyone had ever thought of trying ot hook up a solar panel to a battery and run a thermostat controlled heater off of that. I don't know enough about electricity to know if such a thing would be feasable but it would certainly be cheaper than electric or propane!

Vwetzel, thanks for the info. I won't get one this year but I would like to put one up next year. My Dh thinks it would be very expensive to heat it in the winter. I would love to know how you heat it, how much it costs, and at what temp. you keep it. Also, what "pyl" is the material on your greenhouse? No one here in our small town has one that I can talk to about heating costs, but I know our weather is very similar in temperature to yours. Lou

Lou
I dont heat mine I am expiermenting with the black buckets of water to kinda keep my plants a little cozy in winter. I dont know how it will work out but I got my buckets and lids painted black and tomorrow I will be filling them with water and sitting in the greenhouse where the sun shines all day and close to my plants.

I am still trying to corragated panels for mine. I have it double insulated with bubble wrap for now. Probably wont be till next year that I can get the panels.

vicki

I'm subject to "sometimers" disease and won't remember, but I sure will be interested to know how it turns out for you this winter. I will try to mark this so I can ask you about it then. Good luck. Lou

Since I last posted on this thread I did put 3 five gal. buckets full of water in my greenhouse. The water really never gets that warm. But I am leaving them in there if for no other reason but for some moisture.

2pugdogs
Do you have a lid on the buckets tightly? and painted black?
vicki

I am putting up a 14X16 hobby greenhouse just after Thanksgiving. Another "junker" gave me black 55 gal plastic drums with lids. I intend to line the north and south walls with the buckets used as a base for benches. The buckets are 36 inches tall and 2 feet in diameter. It will take 18 to do what I want. I also bought (right at $100) a 4 ft X62 ft roll of reflective bubble insulation for the north top wall and north half of the ceiling from Farmtek.com...These 2 procedures are supposed to help with both heating and cooling. The reflective foil is suppossed to be good to use on propagation benches too. I wonder if these drums will be able to heat up in the winter months or will it take thru a summer of suns to heat them up enough.
I use liquid detergents in those 200 oz containers. I plan to start to save those for use inside as vickie says the smaller would release heat faster. Milk jugs too I guess, I get those faster.

I too have wondered how to heat one of my greenhouses cost efficiantly. I was suggested to use the barrels also. I have one other problem tho. I have tender new cuttings that need to have heat on the roots. I did a bit of research and came up w/ using a submersible heater and using a pond pump to push water thru tubing running on the underside of the cuttings. I would think a submersible heater would work well for the larger barrels to have higher heat. Will let you know how it works out, under construction as we speak.
Angie

If you have thrift shops or goodwills or salvation armys in your area search out water bed heaters....they are the greatest at the least cost.
That reflective insulation is advertised to be a good heat source, I haven't tried it yet but it makes sense that it would work

Were you suggesting a submersible for each barrel?

large water barrel literature

pictured

vwetzel, or anyone else:

No I don't have lids on my 5 gal. buckets. But I do have lids that will fit them. I am so new at this but would someone explain to me how this method of heating works with the lids on tight. How does the heat escape. Everyone please stop laughing like I said I am new at this.

Linda
Edit to ask do you remove the lids at night or leave them on?

This message was edited Nov 21, 2005 9:32 AM

you leave the lids on permanently....the buckets absorb the heat from the sun, as it gets cooler at night the water in the bucket cools off releasing their stored heat into the area......repeats during sun and cool down

I just went out and put on the lids. Thanks for the information
jackieshar.

I have a 8 X 12 GH, I probably should have more then 3, 5 gal. buckets of water in there.

as many as you can have room for........check the pictured image in my last post....and the literature image on the one before explaining the principal behind the thermal heating...... .These are large barrels , but smaller ones on the benches will heat some too

remembering they need to be a dark color so they absorb the heat

The water storage methods in solar greenhouse construction rely on very large amounts of water, and more importantly, well-insulated construction. The method relies on low-level heat absorption, and releasing it slowly at night as temps drop. The water will not heat up like a hot water radiator. It's the massive amount of water, relative to size of the space, and the ability to retain the heat within the space that makes the system work.

The small solar greenhouse I hope to have up by next spring will only be 10'x12' with an 8'x12' glazed south wall that will be covered with insulating blankets at night. The other 3 walls framed & heavily insulated, as will be the roof. The ground at the perimeter will be insulated with foam to 4' below grade.

For this small, well-insulated space, I'm hoping to keep the space at or above freezing with 6 to 8 55 gallon drums. I could fit a maximum of 10 drums in this small space. With temps that reach to minus 40 degrees, I may have to max the space with drums to hope to keep temps up above freezing.

Wayne

That was most informative Wayne.........Thank you for sharing.

How long do you think in the winter will it take for the large 55 gal barrels to heat up enough to make a difference? I am just now getting started. The greenhouse goes up next weekand the barrels will be filled then. Still having some 70 degreee days but down in the 30s at night.

Tell us more about the insulating blankets. What are they made from? where did you get them? Will you have to manually put them on each night?
My zone is much warmer than yours and I am hoping that the barrels and the radiant foil inside on the north side and roof will be all the heat I need. I am working with a 14X16 double (with air space) poly with a cathedral style roof about 9 ft tall.

Jackieshar

You'll have practical experience long before I will. Looking forward to hearing bout your results. Though I've been reading about this subject for 35 years I never had the opportunity to build my own. The attached one I designed seemed to operate well but the house was sold soon after completion and I wasn't able to track the efficiency. I'll be starting my own soon.

Most of my knowledge is from books and my architectectural training. A particularly helpful book is "The Solar Greenhouse Book" by James McCullagh (Rodale Press, 1978.) Though some new glazing materials, such as polycarb, have been introduced since then, the book is still a wealth of information. Out of print now but there are a lot of copies available online at used book sites like Alibris.com

Your drums should begin to warm up immediately as the soon as the sun strikes them. It will be a slow process as the water begins to absorb the heat, but you should begin to see results as soon as the air temp falls lower than the water temp. The solar absorption method is more suitable and the results more satisfying in greenhouses that are in more "survival mode" than in "growing mode." That is, if you are growing orchids in a constantly warm greenhouse, then this method may not noticeably reduce your heating costs. But if you are interested in growing some of the most hardy greens overwinter and need simply to to keep them from freezing before harvest, this may be most or all the heat you need, as long as you provide means of retaining the heat inside the space.

The insulating blankets I'm aware of are homemade affairs and would depend on materials available, the configuration of the greenhouse and how handy the owner is. I'm planning to make mine using heavy-duty bubblewrap since I get huge sheets (about 6'x20') for free from a canoe/kayak dealer. I haven't designed a system to install/remove it yet. Since I will be glazing only the south side at a steep 65 degree slope, I'm thinking of some kind of pulley and hand crank to raise and lower it with some guide wires stretched to hold it against the glazing. Is the foil you mentioned flexible like the material called a "space blanket?" Attaching it to the bubblewrap somehow may be beneficial.

Rigid insulating panels can be used but there may be a space problem when it comes to maneuvering and storing them. I've seen a small greenhouse whose owners simply cover it with fiberglass batt insulation sandwiched inside tarps. Quick to install, but hard to remove in the morning if it snows overnight. Whatever you install, it needs to be easy to put up and remove without interfering with your plants or flats. It also needs to provide a tight seal.

The simplest "blankets" may be floating row covers. Elliot Coleman uses them in his greenhouses in Maine to grow hardy vegetables in hoop houses. See his book "Four Season Harvest."

Jwest is lucky to have so many sunny days each year. Our climate up here isn't so generous. I know I'll not be growing tropicals in mine, but my goal is to pick salad greens all winter without plugging it into the grid. Maybe overly optimistic but I'll have fun experimenting. Wish I started years ago.

Wayne

check out farmtek.com...for the material called Tekfoil, it's flexible , comes in a roll .It installs over the poly on the inside.... foil side in toward open space .it's kinda like a small bubble wrap sandwitch ...... white on the outside foil on the inside for radiant heat. Can also be used on benches for growing...I like the idea of floating row covers for seedlings.....My land is pure packed sand 40 feet deep......the soil doesn't freeze here. I plan on using white gravel for drainage and the reflective value on the floor.......
Oooo wish I knew a kayak dealer....but I felt blessed to get the barrels. I seem to remember reading somewhere that if you wet the bubble wrap it will stick to the poly if installing between studs or whatever method of framing...

I dont think I"ll be doing tropicals. I like the natural oak woods and tall grassland and wildflower meadows. An early start for my butterfly gardens and a nice tomato every now and then will make me happy. Shelter for the few frost tender hardies I allow myself

I am in my early 60s and this is my first GH venture......surely it's not tooo late

Thanks for your insight,

Happy Thanksgiving ,
Jackie

This message was edited Nov 22, 2005 4:08 PM

Another method of heating the greenhouse is one old timers used. Containers of fresh manure which will provide adequate heat in the south. A friend spreads fresh chicken manure on the floor of his greenhouse and covers with pine straw or wood shavings. Keeps it toasty thru the colder days.

podster I can image what that GH smells like especially when the sun is shining in at full force.

I have an extra swimming pool cover that I'm thinking of rigging in a way that I could pull it up and over my 10X16X8' high greenhouse at night. We are still having temperatures in the 70's many days, and 30's at night. My greenhouse (which has been rebuilt now after being blown down by Hurricane Jeanne shortly after it was ready for use) is very simple - solid wood ends, with an exhaust fan in one end, metal gable-like hoops and covered with the plastic purchased from farm-tek (I don't know the correct term for it). I think I can attach lines to the pool cover (which is like bubble wrap) and just pull it up over the whole house. Would having it on the outside that way, anchored by block or timbers on each side, add to the heat-maintaining capability? (I saw someone post that she (he) is starting at 60; I'm a decade older than that, and have no doubt there's time). By the way, does anyone use halogen lamps for heat?

Thanks.

Howdy givingtrees!

I'm sure any extra layer over your g-house will help with conserving the heat inside. My g-house is double-layered plastic and has an air pocket between the two layers; it really makes a difference. Likewise, I'm confidant your swimming pool cover will help with heat retention. I'd go for it!

As for halogen lamps, I've never used them so can't comment on that. (I know our heat lamps that we use in our chicken brooders sure put out lots of heat though so I bet the halogen lamps would do the same. Wonder how feasible it would be money-wise though...don't those things really pull some power?

And by the way, WELCOME TO DG! Hope to see you around the site!