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Heat Load for greenhouses.

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Wayco Wayne_2
Wayco Wayne_2 Member Posts: 2,479
in THE MAIN WALL
How do you do a heat load for a greenhouse? there's no walls, only glass. A little help please.

Comments

  • Mark Eatherton
    Mark Eatherton Member Posts: 5,875
    R what?

    Single pane would be R 1 to 2, double pane could be R 3 to 5 (with gas) and triple pane could be R 5 to R 7 (also with gas).



    Infiltration could be the killer..



    A over R times delta T = conductive losses.



    Plus infiltration at .018 btu/cu ft/minute times the air changes per hour.



    ME
  • meplumber
    meplumber Member Posts: 673
    Greenhouses are a little different.

    While Mark's method is the more scientific approach, the greenhouse people usually have a heating package geared for the horticultural intent.



    They are usually done for Seasonal, Local, Tropical, etc... That drives the design temp and humidity. Tropical greenhouses are normally designed for 84 F year around indoor temp. Seasonals are 72 F shoulder and 60 F winter indoor temp.



    Greenhouses are the only buildings that I do a radiation only survey on for boiler replacements and even new installations. Because the greenhouse folks always spec the radiation amounts.



    Good Luck.
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    Thanks

    for the input. There are two old rusty peerless boilers rated at 845,000 IBR. There is a primary loop out to the greenhouses with pairs of close tees and a circulator every place they want a zone. I'm thinking of taking out one boiler and putting 2 or 3 mod cons in its place. (for economic reasons.) I'd have all boilers teed into the primary loop and a boiler control staging the boilers in and out. I'd use the old peerless cast iron beatie as the last dollop of heat in the colder weather. I will do a heat load but I agree it would only be a SWAG
  • Bob Gagnon plumbing and heating
    Bob Gagnon plumbing and heating Member Posts: 1,373
    Delivering Heat

    What are you using to deliver heat in the greenhouse?



    Thanks, Bob Gagnon
    To learn more about this professional, click here to visit their ad in Find A Contractor.
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