Bobberman
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Heating my solar greenhouse for starting seeds!

I tried to use just water sotrage for the heat I need but the coold came too quick this year! I was trying to find something that would only give off a little heat just to keep it above 32. I have ver 500 gallons of water in a 15 by 17 greenhouse covered with double plastic! My ideas lately are with propane. First I tried a catalistic burner but it had no thermastat and only a 9000 and higher setting. A 20 pound propane tank would only burn for 35 hours so it was too expensive and to much heat at night! I thought maybe a small one burner propan cook stove placed under a 50 gallon barrel of water would work and will be trying that soon! I also thought maybe a one mantle propane latern would give off enough hea and give light to the lants at the same time and I will try that also. With the latern I will get a latern tree that hooks to a 20 pound tank which should last for a month! I have no electric in the greenhouse but can run a line there for light or a fan but heating it that way would be too expensive! Any ideas?????

wordwiz
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No ideas yet, but a question. Why are you starting seeds this early, given your location? Long time before Frost Free.

Mike

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soil
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we have an unheated greenhouse and the only things were planting now are things that need cold stratification. this way they get there cold and then get the benefits of an early spring in the greenhouse. I also use them as indicators of when to plant certain things sometimes.

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farmerlon
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It might not work in your situation, but I was impressed with this idea for heating greenhouses ... https://www.growingpower.org/
(I can't find them right now, but remember seeing several pictures at their web site)

That Northern "urban organic farm" uses large piles of compost, piled both inside and outside their greenhouses, to help maintain workable temperatures.
I thought that was a great idea to get some more "passive" heat.

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Gary350
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25 years ago when I lived at the other house I had solar. I was using 3 barrels of water 55 gallons each. The sun would heat the place up to 100 degrees during the day it the winter even if the temperature outside was very cold. The temperature of the water never changed more than about 1 or 2 degrees.

I had to used a very large radiator and pump to transfer heat to the water. The water pumped through the radiator and a fan blew through the radiator. I could get the water to 100 degrees F that way. Then at night the fan needed to run to transfer the heat out of the water to heat the space that needed to be heated. I had to pour 1/4" of oil on the surface of the water to keep it from evaporating from the open top barrels. It worked good once I got it figured out. The radiator was about 3" thick about 24" wide and about 18" tall. The pump was 5 gpm running on a small electric motor.

I was using 2 layers of glass at the time. I tried 2 layers of polyethylene plastic first but it would not work. The wind would blow and suck the plastic in and out. The movement of the plastic acted like an air pump it sucked the heat out and the cold air in.

garden5
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I never thought about the "pumping effect" of the plastic, but that makes sense. If your greenhouse is covered only by sheets of plastic, that may not be enough to keep the heat in and the cold out very effectively. Is your greenhouse only plastic or does it have some glass panes as well?

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ozark_rocks
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I am having the same problem you are. While the day temp has hit 96F, it has dropped to 12F at night. We put a small camping heater in and brought the temp to above freezing, but I'm afraid it will use to much gas. I'm thinking about only heating part of my greenhouse. Or setting water filled jugs around the plants I have ready to move in it. I'm starting everything in my kitchen, and keeping it under growlights, untill I figure out how keep the night temps above freezing. I like your idea about useing a lantern, that would work on a small area, I think. This is my first greenhouse, and I don't want to kill any plants while working out the problems.

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soil
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if you cant hold heat at night you need more THERMAL MASS. that means get some 5 gallon buckets of water, 55 gallon drums, cob, anything to capture that heat you get in the day and slowly release it over the night. paying to heat a greenhouse is not the smartest thing to do, it will cost a pretty penny.

PS: salt water holds more heat longer.

wordwiz
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soil wrote: paying to heat a greenhouse is not the smartest thing to do, it will cost a pretty penny.
Depends on what you mean by pretty penny. I heated my GH last winter and it ran about $50/mo. I did have two layers of glass/plastic and the north wall was OBC board with R-23 insulation but it was also 196 sq. ft. with the average ceiling height 7'. But it was a relatively cold January - one day it did get up to 51 but most of the month it was in the teens and twenties.

I plan on using it to raise seedlings in this spring but I should need heat at all, at most for a couple of nights in March.

Mike

Bobberman
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The radiator to me is the answer. Even a combination of a radiator and a water baseboad heater! Using the two together gives heat faster both to the 55 gallon drums and the col night air! There is plenty of wased daily heat in a greenhouse to save in the water for the night! The fan will help some but can cause a colling effect if their is mosture or it can dry the plants! I think a light fan woud be better at night when the heat needs moved around! Old hot water tands are also good to hold heated water! If you use a radiator insulate the bottom of the drums. I would also run the pump to the radiator day and night. The only time I would shut the pump off is at the first two hours hours of dark unless its a loudy day and little heat is absorbed by the drums! I have 500 gallons in my greenhouse and think thatI want to double it. The reason is because the water also keeps the greenhouse cool in the spring or when its really hot outside! I like to have the drums under some of the plants on the noth side!

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rainbowgardener
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I couldn't find it on the growing power site ( https://www.growingpower.org/index.htm ) but from hearing Will Allen talk (an amazing man!) I know that they use compost to heat greenhouses. Have an active compost pile inside the green house and pile hay bales along the outsides. The hay insulates and also gives off heat as it breaks down.

Bobberman
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I also have heard that they make a outside compost using chicken or any type of manure in a large pile and have a radiator in the middle! The radiator collects the heat as the water is pumped through it. The water is sent into a large 150 gallon tank inside the green house where the heat is distributed through the green house using basebard heaters! This tank can be placed anywhere if it is insulated and will hold hot water for days but the compost will constantly give off heat! Any type of nitrogen fertilizer will aid a compost like blood mill or urea but not too heavy! People even use compost activator to aid composting! Its pretty easy to set upa two radiator system to collect heat from a compost source or from a outside fire. ASll you need is two old radiators a flexable 1 inch underground type water pipe that comes in 100 foot coils a small watyer pump and electric. A thermastat is opional. Coming from the burn pile a metal pipe mst extend to the lastic pipe. The heat of the fire will not harm the radiator as long as there is water flowing through it! A small fire every other day will fill he 150 gallon tank with plenty of hot water! I hope this inspires some of you to try it!

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soil
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bobberman look up the jean pain method of composting/heating. he does amazing things with the method.

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Gary350
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You need to be able to collect the heat and release it again at night. A 55 gallon barrel of water won't change temperature more that 1 or 2 degrees in 24 hours and 5 gallon buckets won't change more than about 10 degrees in 24 hours. You have to increase the surface area many times over to store heat then release it later. A radiator with a water pump works good on liquid. Small loose gravel and a fan works good too.

garden5
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The compost thing makes sense since, at its peak, compost will reach 130 degrees F inside. What a great idea of taking that heat and transferring it to the greenhouse.

I'd really like to get a greenhouse and use it for starting seeds since I want to eventually grow more than I am now and be able to up-pot all of the seedlings to bigger pots, as well. This would require 12+ 4ft. shoplights. I thought that, in the long run, a greenhouse wold be cheaper since it wouldn't cost me an electric bill increase for3 months out of the year.

However, reading this thread it seems like it's going to cost me to heat the greenhouse Feb-May, anyway...so maybe it's not really worth it :?. I'm glad to read these reports because I always thought that a greenhouse stayed warm enough on its own to grow plants. Perhaps this is true in some areas, but probably not in mine.

OK...back on topic :roll:.

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applestar
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I'm not financially or project-wise ready to build any kind of a greenhouse yet.
It's frustrating because I have a kit in the shed -- a big lean-to model -- that after purchase, we decided we didn't want to build against the house. Then other things happened to prevent taking any further action and the whole thing has been stored away ever since.

Now, I want it, but DH still doesn't want it. :roll: (Besides, I've planted all around the house in the interim so entire beds will have to be transplanted :roll:)
It'll be a whole another BIG project to try to ... what? get rid of it? trade it on Craigs List for free standing one? Whatever. So, it sits.

But with the thing on the back of my mind, you can imagine that I spend periods of time each year dreaming how I might set it up. :wink:

One of the ideas I was playing with is to have a row of those black rubbermaid stock tanks along the north wall. Use them for aquaponics and heatsink. Set up benches on top in such a way that water can be pumped up and drain down.

I thought I would do the hay bales along the base of the outside wall, and have the compost pile next to the greenhouse to somehow pump heat into it, so these discussions have been illustrative and illuminating. 8)

A lot of old horticulture books (and classic British mysteries :>) talk about "manuring the hothouse beds" in fall and planting directly in the ground. It's been difficult for me to reconcile these images with the modern greenhouse plans that almost always seem to have graveled of paver block floor (or even landscape fabricked floor) and "benches"/tables. I think I see raised beds in the photos of DDF/Eric's greenhouse. Elliot Coleman's high poly tunnels are planted directly in the ground. The one I've seen in his Four Season Gardening (or similar name) book is, I believe, a movable tunnel that is positioned with the one open end directly on the house kitchen wall.

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The Bearded Farmer
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Nice little set up you have there Hatter. Only tip I have is add one more light fixture. The reason I say this is because you might get the seedlings at the end of the table bending for light.

I might be trying something similar when I build the greenhouse.

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jal_ut
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Keeping a greenhouse operating through winter is a tough proposition.
If we just want to start some plants for planting out in spring, we don't need to start too early. About 6 to 8 weeks before planting out time is soon enough. Shut the greenhouse down in the coldest months.

When it comes to the cost of heating a greenhouse, it may be better to just buy nursery plants for the few plants we actually need.

Ya, ya, I know we just like to grow things. :)

There are some good plans for Solar Greenhouses. These are not low dollar things, but do work quite well. Basically the North wall, the North half of the east and west walls and the North half of the roof are solid insulated walls; like a regular insulated building. They have cement foundations that are insulated on the outside so the concrete also enters into the mass. The other half of the building is double pane glass panels. Heat storage mass is provided by at least six 55 gallon drums painted black and filled with water. The floor is earth which is also part of the mass heat storage. Yes, to build something like this is costly, but if you are into spending money for a play thing, it could give you years of pleasure.

Do a Google search for Solar Greenhouse.
"Passive Solar Greenhouse" too.

garden5
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Thanks for the suggestion, Jal. You do put my scenario into perspective: I just want to be able to start and up-pot a few hundred plants in the coming years as I create more gardening space. Yeah, it seems like a lot, but if you plant then densely in beds (what I would do with them if/when I get to that point) 100 pepper plants would only take up about a 5x20 area or so.

Anyway, I would wind up using the greenhouse from about mid-March to mid-May, so perhaps by this time the greenhouse will be able to heat itself? I'm going to have to look into this quite a bit more before I actually go out and buy one.

DoubleDogFarm
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There are some good plans for Solar Greenhouses. These are not low dollar things, but do work quite well. Basically the North wall, the North half of the east and west walls and the North half of the roof are solid insulated walls; like a regular insulated building. They have cement foundations that are insulated on the outside so the concrete also enters into the mass. The other half of the building is double pane glass panels. Heat storage mass is provided by at least six 55 gallon drums painted black and filled with water. The floor is earth which is also part of the mass heat storage. Yes, to build something like this is costly, but if you are into spending money for a play thing, it could give you years of pleasure.
James,

I've seen a greenhouse a lot like the one you described. Now where did I see that. :lol:

[img]https://i67.photobucket.com/albums/h300/eric_wa/Double%20Dog%20Farm%20Greenhouse%20Photos/DSC01957.jpg[/img]

Currently my setup is half greenhouse, half tool shed. The north wall down the middle is insulated.

Soon I will be removing the center wall and turning the whole building into greenhouse. I'm in the process of collecting all the components to build a [url=https://www.motherearthnews.com/Do-It-Yourself/1976-11-01/Wood-Hot-Water-Heater.aspx]Blazing Shower Stovepipe Water Heater[/url].

Instead of using wood, I will be using a [url=https://journeytoforever.org/biofuel_library/ethanol_motherearth/me4.html#mwoh]waste oil burner[/url].

Using this old potbelly stove, I could also burn wood in it.

[img]https://i67.photobucket.com/albums/h300/eric_wa/ComfortStove004.jpg[/img]

This setup should heat the greenhouse and supply warm water for aquaponics / tilapia. Before the aquaponics, I will probably use the warm water for bottom heat propagation.

I second the motion, we need a Greenhouse Forum. :wink:

Eric
Last edited by DoubleDogFarm on Tue Oct 04, 2011 1:00 am, edited 1 time in total.

Bobberman
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wordwiz wrote:No ideas yet, but a question. Why are you starting seeds this early, given your location? Long time before Frost Free.

Mike
I am not starting seeds this early but I have some lants from this summer and flowers that I am trying tokeep all winter. Most of them died but a few ae still left. I am trying to learn this winter for next winter. I would like to raise some crops all winter! The coldest it seems to get is 25 even when it is 5 outside. I am thinking that the water changing to ice must be giving off more heat durig the phase change!! Gardening and greenhouses seems to spur the mind to be creative or even invent new ways!

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rainbowgardener
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Even if I had room for a greenhouse, I've never had much ambition for one. I'm in the garden through October and start my next seeds in January. I don't mind having that little break, in which to get all my Christmas projects together.

What I do have is a regular metal 5 shelf system that I wrap in heavy plastic. Put velcro strips up the middle so it can be opened and closed to care for things and also for ventilation. Sort of a cheapo-homemade version of this:

https://www.ivgstores.com/IVG2/Y/ProductID-83697-.htm

It allows me to put seedlings out a little earlier and helps with the hardening off process - gives a more protected space to start plants getting used to outdoors. I only use it for about 6 wks in the spring and then put it away again.

garden5
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DDF, I was picturing your greenhouse in my mind while I was reading Jal's post!

I just noticed in the picture you put up that you did not include an overhang on the side of the shed that is the greenhouse. That's pretty good foresight! I had to think about it at first, but then it dawned on me that (DUH!) you want sun to get into your greenhouse so you don't want to shade it.

I especially like your idea of using the oil/wood burning stove. That may be a solution for some of us: heat with wood. If you have land, the wood would be free and you would thus only pay a one-time cost for the stove.

Maybe put the stove right in the greenhouse, only lighting it up at night, or do you think that would make things to hot?

DoubleDogFarm
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[img]https://i67.photobucket.com/albums/h300/eric_wa/DSC00958-1.jpg[/img]
I just noticed in the picture you put up that you did not include an overhang on the side of the shed that is the greenhouse. That's pretty good foresight! I had to think about it at first, but then it dawned on me that (DUH!) you want sun to get into your greenhouse so you don't want to shade it.
G5, You are correct.

I like the looks of overhangs on buildings and think it looks cheap if they don't have them. Not on greenhouses.

The waste oil burner, is someone going to say boo on this, will be in the greenhouse. The furnace is coupled with a old hotwater heater storage tank. Themal siphon, circulation pump, and tubing.

Example
[img]https://i67.photobucket.com/albums/h300/eric_wa/Thermalsiphon.jpg[/img]

Instead of radiators, I'll have tubing for bottom heat. In the future, I hope to heat fish tanks.

I'm also thinking about pulling the duck house over and connecting it to the greenhouse. Might as well keep the ducks warm also. :D

Eric
Last edited by DoubleDogFarm on Tue Oct 04, 2011 1:01 am, edited 1 time in total.

Bobberman
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My 500 gallon of water heat storage is not enough yet with the outside temp still arounds 10 at night! The other problem is the snow on the plastic! I swep it off when I am there on the weekends but the sun cannot heat it much with the snow! I got my boxes started this past week but did not plant the seeds yet. I used about 10 6 inch boxes and put a sheet of news paper at the bottom with leaves on top and some urea and blood meal with some garden soil on top about 4 inhes deep! I put a layer of seed potting 2 inches on top of the compost mix at the bottom! I am hoping it heats up in about two weeks when I start the seeds! I even put a layer of rabbit manure in several boxes! I will see what happens! I am hoping it heats up a few degrees for a few weeks!

Bobberman
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I tried my newest sorce of heat for my solar geenhouse this past weekend! This may sound unusual bu it seems to work. I will report on it next week as to the temperature change from day through the night! I took several car tires and put 8 bricks inside the tires I put the tire into a clear plastic bag and sealed I! The sun and the heat in the greenhouse heats the tire quick and extra warm heating also the brick! Because the rubber is a insulator it gves of heat slowly at night and seems to hold the heat longer than the water! I am going to stack 4 tire this week with a layer of 8 additional bricks between each tire plus the 8 inside! This I think will work better than the 50 gallon drums I use now! Each method of collecting heat works different and using several types together gives a more uniform heat! It also has a better cooling effect when the greenhouse is too hot!

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applestar
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it was kinda warm -- 40's and 50's AND sunny.. Might even have hit 60's at one point... -- this weekend so it may not be as good an indicator.... (at least here in NJ -- The snow finally started to melt and I could actually see my brick patio and the surrounding ground yesterday! How about in PA?)

I think I'm going to "soak up" all this information this winter and aim for next winter's NEW PROJECT! :wink:

Bobberman
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Pa. was warm in the upper 40's for a few days and in the 50's today and thursday. Then cold at night again! I am hoping my seeds get the start from the warm weather. I don't mind a 25 degree night once my water warms up since I have over 500 gallon in the greenhouse! I just hope it does not get cloudy and cold for a whole week! I am planning on puting another 20 boxes in this week and adding 3 more cold frames! I put in a cold frame of 4 by6 with peas this past wekend and another with lettuce and cabbage!!



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