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Thread: Conserving heat

  1. #1
    Join Date
    Feb 2002
    Location
    Surrey, BC, Canada
    Posts
    221

    Conserving heat

    Just got my greenhouse built, but like I think it was Sue mentioned, it costs a lot to heat the whole thing. Still running a double poly low tunnel with dependable heat in there, as well as the 3 tier growlights indoors.

    How has anybody managed to heat their structures without throwing away an awful lot of money?

    I'm wondering about energy curtains for one. I've already thrown a layer of row cover (polyester) over the more tender plants, with just an electric heating cable nestled around the pots to keep the roots from freezing so bad. This has really helped, as temps in the open greenhouse get almost as cold as outside without any other heat source in there at night.

    Still planning to put in a (gas fired hot water) heating system, but still don't want to be throwing $ away. This greenhouse is supposed to make money, not bankrupt me!

    Glen

  2. #2
    Join Date
    May 2004
    Location
    SE PA, zone 6b
    Posts
    217
    Seems to me that if hot water pipes were placed just below the benches, that would keep the plants warm enough without having to heat the entire bldg.

    Also, if a sheet of plastic were to be installed as a kind of low ceiling, that would cut down on what needs to be heated.

    On the really freezy days or nights, perhaps some row fabric just laid on top of the plants.

    Rabbits and chickens provide 8 btu's/ # of body weight.

    If you are not using all the space in the gh, gather all the plants together at one end and curtain off the unused space.

    Finally, hay bales around the outside would insulate the space even more.

    Best wishes,
    Last edited by 3girls; 01-16-2005 at 11:47 AM.
    Sandi
    SE PA, zone 6b

  3. #3
    Join Date
    Feb 2002
    Location
    Surrey, BC, Canada
    Posts
    221

    saving heat $

    Sandi--we think alike!

    The system my neighbour (HVAC company owner) has envisioned for me is basically a hot water tank feeding hoses with warm water circulating thru them. He agreed emphatically that heating the air is not what we wanted to do, the more we could just heat the plant itself the better.

    And my row cover laid over the clematis and phormiums in there right now has worked well during our cold snap. Just want to bump up the heat for getting seedlings, veggies and assorted other stuff going in another month or so.

    Agree that installing poly under the "ceiling" will cut down on the area heated, I think that's the idea of the energy curtains tho I've never actually seen those working. Poly is not much of an insulator, as you know, there are other sheets (aluminized?) that are made specially for this. Not sure how I'd suspend it but at least there is some greenhouse framework available so I'm sure I could work something out.

    For that matter I could just set up a low poly tunnel right in the greenhouse, and heat that much warmer than the rest of the house. Really don't want my 20C air right up against the greenhouse roof where it's below 0C on the outside...like trying to heat the whole outdoors.

    Because I went with a ridge rollup style, which has certain advantages esp. growing the hardy ornamentals I mostly work with, I couldn't at the same time instal double inflated poly. I realize that the double roof is a great heat saver if the style of house allows. The infrared poly is another good investment.

    Glen

  4. #4
    Join Date
    Aug 2001
    Location
    Zone 9a - Gulf Coast
    Posts
    9,934
    It dropped to 26 degrees F. this morning, felt like 16 degrees, so I grabbed my industrial A/C thermometer and headed for the old greenhouse.

    Sure enough, there was a light frost on the inside of the south faceing window. The thermometer on the inside wall of the greenhouse said 28 degrees. As I looked around at the plants inside, I couldn't see any damage. The beads of water from a late afternoon sprinkle was still on the leaves of the daylilies placed in the center walkway.

    There was condensation on the north window which is somewhat protected from a newly built shed.

    I left the A/C thermometer on top of one of the daylilies and came back 15 minutes later. Still 28 degrees on the wall thermometer, but the A/C thermometer said 38 degrees.

    The warmth of the ground (dirt floor) is the only thing that was keeping the central portion of the greenhouse warmer.

    The greenhouse is corrugated fiberglass. It was once somewhat clear/white, but has aged. The outer coating has worn off, and you can actually see and feel the fibers. Definitely not what it used to be and in need of replacement...

    A small ceramic 1500 watt heater is what I have used in the past to heat the old greenhouse, but it broke a year or so ago. I also have flood lights along the top which I used on barely freezing nights. Both did fine on keeping the temperatures about 32 degrees F.

    BWI tells me that double poly with heated inflation blowers is used some here, but I've never seen them in use, probably because I am never near one of these type greenhouses during the early hours of the morning.

    My patio didn't go below 48 degrees according to the thermometer on the east wall. That side is lined with 4 mill clear poly. The west and south walls are the house. The north wall connects to the new 'porch' which is lined with cheap 6 mill plastic.

    I used a 1500 watt quartz (electric) heater in the doorway facing out toward the porch. We lit a kerosene heater (on low) at 9 PM near the north wall of the porch. The porch was about 45 degrees.

    I don't know how much all of that will help you, but perhaps at least you could heat your greenhouse durng the last 6 weeks of cold so that you could get a jump start on the spring.

    There are so many variables, it is hard to say...
    Ann B.
    Zone 9a
    Gulf Coast


  5. #5
    Join Date
    May 2004
    Location
    SE PA, zone 6b
    Posts
    217
    Eliot Coleman says that row cover adds 1 1/2 - 2 zones to the plants it covers. I think building hoops over the seed trays with heat underneath them will do very well. In one of the articles I have collected by him, the picture showed wire bent into a square about 8" over the plants. Ann, you should be just fine with row cover over your plants.

    Glen, I talked to my sister in Anacortes last night. Man, you guys are sure getting hammered. The nice thing is that by the end of Feb, you should be just fine. Although, once in the 30 years I was there, we had a 2-3 day ice storm on the fourth of Feb, and again on the fourth of Mar. It was clear sledding after that. I also remember just once that there was about a 10 day sustained freeze that jellied up the roads for awhile meaning that the school buses couldn't run.
    Sandi
    SE PA, zone 6b

  6. #6
    Join Date
    Aug 2001
    Location
    Zone 9a - Gulf Coast
    Posts
    9,934
    Sandi,

    I have used the row cover (frost blanket), and I love it!

    Right now, I only have the thinner kind that offers down to 28 degrees F. protection. I have doubled it for greater protection. The advantage of the frost blankets are that they can be left on all the time. The plants will stll get some sunshine and rain.

    It is especially great for low growing plants, but sometimes difficult to keep pinned down for taller plants or vines in cages.

    I am a believer in the material. I have also used old comforters and blankets in areas that are not large. I used one last night on the Thunbergia, not because it would die. It wouldn't. But it is herbacious and has grown 8 inches. The disadvantage is that heavier material weights down tender new growth. Another disadvantage is that they really get heavy and need washing and drying if there is rain.

    I'll try to take of picture of the Thunbergia that wintered over under an old comforter last night...
    Ann B.
    Zone 9a
    Gulf Coast


  7. #7
    Join Date
    Aug 2001
    Location
    Zone 9a - Gulf Coast
    Posts
    9,934

    As Promised...

    Saved by an old comforter...

    They are wilted, the tender branches just bent slightly due to the weight of the comforter.

    Thunbergia Battiscombei:
    Attached Images  
    Ann B.
    Zone 9a
    Gulf Coast


  8. #8
    Join Date
    Aug 2001
    Location
    Zone 9a - Gulf Coast
    Posts
    9,934

    NOT Protected

    New growth on my grandmother's crinum...
    Attached Images  
    Ann B.
    Zone 9a
    Gulf Coast


  9. #9
    Join Date
    May 2004
    Location
    SE PA, zone 6b
    Posts
    217
    On another forum, I found www.greywater.com on which I found this drawing--hope it copies. If not, go to the above site, scroll down on various pages until you find the greenhouse.

    ******Well, that didn't work. I believe I found the lean-to greenhouse under "Treatment"

    Good luck.
    Last edited by 3girls; 01-17-2005 at 12:54 PM.
    Sandi
    SE PA, zone 6b

  10. #10
    Join Date
    Aug 2001
    Location
    Zone 9a - Gulf Coast
    Posts
    9,934
    Indeed, it is under treatment (after you go to the website)....

    Here's a direct link. You need to scroll down a bit to see find it:

    http://www.greywater.com/treatment.htm

    With recycled bottom rock heat, no less!

    Neato! Thanks for sharing!!!!
    Ann B.
    Zone 9a
    Gulf Coast


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