Heating my greenhouse

Re: Heating my greenhouse

mike90045 wrote: »

I'm tracking this thread, as I also co-habit with a SWMBO.

Ditto from me too! In fact this coming weekend is one of those!

Re: Heating my greenhouse

Cariboocoot wrote: »

Electric heat is terribly inefficient. Solar Dave's suggestion of mass storage (and a bit of insulation) will work far better.

Minor point of correction: electric heat is 100% efficient, you put one kilowatt of energy in, and get one kilowatt of heat out.....zero waste.

The problem is the generation of electricity can be extremely inefficient....which I'm sure is what you meant.

In this case, 45w probably won't even keep up the self discharge on that size battery bank, much less leave any to work with.

Takingtime1 would do far better to do as ya'll have suggested, and build a well insulated greenhouse with lots of thermal mass to minimize the amount of heat needed to start with.....then use solar for direct heating of air or water, and store it for overnight/cloudy days.


Hey...that's what I'm doing !


When I first set up my PV system, I need a "power room" out as near to the arrays as possible to house the gear and batteries. So I benched out a place in the south facing side of the mountain, and built a combo solar room/greenhouse ( SWMBO got the greenhouse part ).

Initial construction:

The small 4x8 section on the front left side is my power room, the 12x20ish on the far end is her greenhouse.



The back, far end and front wall are all earth bermed. The front is a permanent bed of strawberries outside now.



Homemade rafter/trusses made of 2x6 treated lumber/plywood gussets, on 24 centers. You can see the trackers I built for my two initial arrays before the drive actuators or panels were installed.



Same shot, taken from the house garage door.

Re: Heating my greenhouse

Cariboocoot wrote: »

TnAndy;

That is some fine building!
Unfortunately I shall have to delete the pictures to eliminate any possibility of my wife seeing them.
(Just kidding, of course.)

I completely understand....a man's gotta do what a man's gotta do.....ahahahaaaa

Re: Heating my greenhouse

here's the solar water heating shed:
http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/solarshed.htm

Re: Heating my greenhouse

How about a compost furnace? Gardens and greenhouses produce lots of biomass. Why not put it to work heating your greenhouse? I am yet to try it, but seriously considering the idea for our greenhouse-to-be. I have friend who's tried it in his greenhouse. He does employ multiple techniques (compost, insulation, thermal mass), but he manages to keep his greenhouse above freezing through Montana winters. Here is a link to one if his blog posts: http://montanawildlifegardener.blogspot.com/2009/01/heating-greenhouse.html

Re: Heating my greenhouse

I fought the keep-it-warm-enough-in-winter thing for several years, refusing to consider gas or electricity. I gave up. Some vegetables are sensitive enough to temp' that even a few nights of cold will disrupt their growth/fruit set. Plus, as someone else alluded to, many plants, such as those in the tomato family, need a certain number of hours of light to set fruit or to produce fruit that is edible. Plus, that light must be of sufficient quality and strength. Lost of $$$ to set up some sort of light system and lots of electricity to run them. Not really useful for people of average financial resources and just growing for a household. Maybe ok if you are selling fresh produce to restaurants or whatever in winter and can charge a premium in a commercial operation, I suppose.

I now let my plants go by about October and the greenhouse rests til spring. I can use it for germinating new plants from seed starting anywhere from January to March, though the earlier winter months are still dark and cool and the seeds are not as fast to germinate and the seedlings don't grow very fast. I've found, for my high Colorado area, starting seeds in the greenhouse is about as effective in March or April as January, they grow that much faster in the early spring anyway. Last year, I started some seeds in Jan. and some in May, to test this, and by the first of June, the plants were all the same size.....

The heat-water thing, with solar water heaters or any other method, would probably lessen or eliminate the winter temp' swings in my greenhouse. However, enough volume of water will take up much space. I don't care how big the greenhouse is, before long you'll want even more room for growing. Dedicating room in the greenhouse to water storage must be planned and engineered carefully to prevent losing too much growing area. If outside the room, maybe better but not an option up here where I am.

I do keep my herbs in pots so they can come into the house proper and live on windowsills during the winter months. The lower light/shorter days slow them way down, too, but I plan for that now and have many more pots of basil, etc., that I could ever use during the summer.

Re: Heating my greenhouse

Yes, burying would be an option some places. Not here. We sit on pretty much solid rock. It would take a major dynamite/drilling operation to get a hole. It could be done in an above-ground shed or something, then piped into the greenhouse. I don't have the room for it.

Some friends of ours in a different area dug a huge hole next to their home and filled it with rock. They ran air through the rocks, air heated by panels on the surface. They had a way to blow air through the rock and into their basement through vents, then the air made its way through their upstairs and was exhausted to the outdoors. The idea was that the rocks, once heated up, would provide a fairly even source of heat even when the sun wasn't shining on them, a heat-sink to keep them warm around the clock and keep them warm on cloudy days. It was a pretty slick and technical set-up and you could stand next to the vents in the basement and feel warmish air coming out. But it was not hot air or even REAL warm air. After a few years of trying, they mothballed the system. It kept the house from freezing [protected the pipes if they were gone] but they were not warm enough for any comfort. They'd spent a lot of money on it, and perhaps a water system would have worked better. Maybe.

Re: Heating my greenhouse

Just throwing out an idea, why couldn't you use a tank(s) as legs for a growing table. (set a wood table on top of a tank) Surely not everything sits on the floor....?