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Thread: My New GH In Constrution

  1. #17
    Tony Paroubek's Avatar
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    BTU calculator. Adjust the materials and shape/size of the various walls and such..

    You can plug in various numbers such as your coldest winter temps to find out how much heat it takes to maintain your desired temperature on the worst case. Or you can use your Winter average temperatue for a few month period to find out what it will take on an hourly basis to heat over that time frame.

    http://www.igcusa.com/greenhouse-btu-calculator.html

    ---------- Post added at 03:43 PM ---------- Previous post was at 03:06 PM ----------

    I ran some numbers for fun.

    Assuming 70 temperature average inside temperature... figuring your nights will be a little cooler and your days a little warmer. Not sure if you plan to just run a single temperature or moderate between day/night.

    For outside average temperature I split the average low and average high for the end of December in your neck of the woods. That gave me a figure of 30degrees

    6.25' wide, 8.4' long, side walls 6.4 feet high
    8mm double wall poly carbonate (these kits usually have 4-6 mm poly carb. but I couldn't tell from the photo). I figured it was safe to use the 8mm figure though since it probably about balances between thinner poly carb and adding some bubble wrap.

    plugging this in gives me a figure of 7000 btu/hour

    So basically what this means is it will cost an average of 7000btu/hour to heat your greenhouse over most of Dec. Jan. and Feb.

    So if you want to figure your cost.. 90 days at 7,000 btu/hour x 24 = 168,000 btu/day
    Propane has 92,000 btu/gallon so it would take about 2gallons of propane/day. Propane is about $2.50 gallon.. so $5 day.

    If you are planning to use electric then you probably need a 240v line..
    A 240v 4000w heater will put out about 13,500 btu/hour

    To figure how much electricity it would use..
    7000 btu/hour x 24 = 168000 btu/day divided by 13,500 = 12.4 hours/day the heater will run x 4kwh (4000/1000) = 50kwh/day
    Take the 50 and multiply by your kwh delivery charge and supply cost to find out the electricty cost/day

    My power company charges 8.5 cents for delivery and 8 cents per kwh so 50 x 16.5cents = $8.25 day in electricty cost.

    Plugging in the extreame temps during the night.. and maintaining 60degrees during a -15degree night. It will take 13,000 btu/hour to maintain 60degrees. So a 15-20,000 is should be sufficient.
    Is that a Nepenthes in your pocket or you just happy to see me?

  2. #18
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    Qeastion is Tony In Your professional opinion do think it will all work if i can at least keep teh temps at lets say 65 an Humidity above 70% i think all will be fine .
    but Tony What do you think

    daren

  3. #19
    Tony Paroubek's Avatar
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    Humidity won't be a problem during the Winter when the greenhouse is closed up. It will be a problem during the Summer when the vents are wide open! So you will need to come up with a plan to help keep the greenhouse cool and humid during the Summer.

    Can it be heated? sure.. heating is easy. The question is with what are you going to heat it and what will it cost? What did you have in mind?

    You could also look into some passive solar.. ie big water containers that heat up in the sun during the day and release heat at night.
    This place is good for supplies:
    http://www.growerssupply.com

    Natural gas is probably the cheapest, but requires a gas line.
    Electricity requires a heavy cable to supply the heater, otherwise easy to install. Can be expensive depending on your power company...
    Propane is the simplest and easiest to install but on the expensive side.
    Oil is more economical than propane but only good for larger size operations due to furnace sizes.

    Bubble wrapping the inside will help alot. When the sun is up it will also help alot. The other 14 hours of the day though... Reducing your temperature during the night will help alot also, but you can only go so far with that depending on what plants you are growing.


    Don't forget you will also propably want to have some sort of power to run some fans and pumps and stuff, as well as water supply of some sort.
    Is that a Nepenthes in your pocket or you just happy to see me?

  4. #20
    mark.ca's Avatar
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    You can mount a misting system to operate during the summer to keep up the humidity.
    Best regards,
    Marius

    My Website: http://droseragemmae.com/

  5. #21
    Admin- I'm growing CPs in the Desert of Tucson, Az. adnedarn's Avatar
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    I have a true to life example of heating costs Although my temps are quite a bit warmer than you! This is on my 8x16x10 g/h with 4mm twin wall poly. The heater maintains 60f but so far has only been used at night as the days have no problem warming up (and requiring the cooler to keep it down around 85f) I filled a 100lb propane tank on 11/13/09 to the tune of $51.35 (2.20/gal @22 gals) I was in the g/h this morning before work packing an order when the heater went out (already had the other tank in my truck to fill today ) Anyway... That means that tank lasted me 20 days only being used to heat at night at 60f when my nights have been somewhere in the high 30s,40s and low 50s. That's about $2.57 a day. Now, although- we're starting to get cooler... Soon it will be time to take the shade cloth off to aid in day time warming.

    I agree with all the stuff Tony has said, heating is fairly easy but not cheap. Cooling and keeping humidity up is the trick (especially for me!).

    Andrew
    Last edited by adnedarn; 12-03-2009 at 12:28 PM.
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  6. #22
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    Day two:







    Day 3 :











    30 amp Cable



    The End


    Thanks Daren

  7. #23
    Tony Paroubek's Avatar
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    What's the one picture with the plywood/fiberglass batting?

    Some additional thoughts based on your site. The end wall next to the house and the vertical wall on the deck side I would use 2" thick rigid foam insulation and panel the inside completely. You won't get much light through either wall based on their proximity to the house and the deck. That will give you an R14 or so insulation on those portions, which will help alot on the heating.
    Is that a Nepenthes in your pocket or you just happy to see me?

  8. #24
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    Quote Originally Posted by Tony Paroubek View Post
    What's the one picture with the plywood/fiberglass batting?
    I Insulated the Floor.

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