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greenhouse floor

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cbs
cbs Member Posts: 1
in Radiant Heating
new viewer here with a ?

 i have a client with a 30x60 arched, fabric covered greenhouse with a pea gravel floor.

?  can i put in a radiant system that does not involve a slab?  can i put down foam insulation on grade with sand on top, radiant then more gravel?   any help greatly appreciated.

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  • mike parnell
    mike parnell Member Posts: 42
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    gravel floor

    Ive got a 30 x 60 greenhouse with a polycarbonite roof,double wall poly, and a 3/4 stone floor. it is heated with a 225,000 btu propane hot air heater.. if it were me I would insulate then pour a concrete slab with the tubes in it but near the top, not the bottom of the slab, the loose stone wouldn;t hold the heat like concrete does.  If you  plan on  keeping the plants on ot near the floor , the plants will do fine..good luck with your project... mike
  • Gordy
    Gordy Member Posts: 9,546
    edited February 2011
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    pumping tubing

       A long with the fact that fill material is a pour conductor of heat transfer capability, another issue would be the tubing pumping up through the gravel after a period of time.  Your going to have water saturating the ground year round, and this will make fill unstable. Trying to get suitable drainage with the foam as a barrier could prove to be a challenge also.



     Either pour a slab with insulation under it, or go from above with fan coil type emitters as the other poster has done with his.  Over head radiant with gas tube is a thought, but may not prove to be a good marriage with fabric? covering unless you have the height to keep good clearance from combustibles



     Gordy
  • TMorg
    TMorg Member Posts: 23
    edited February 2011
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    Greenhouse

    In the early 80s I designed a 30,000 sq. ft. greenhouse - 2" polystyrene, 4" of sand with 2" of gravel. It is still working well. It works much better when moist. The huge advantage is they place the plant pots on the gravel. The boiler is controlled by a thermister in the pot soil. The air temp. is quite cool but the roots are warm. This keeps disease down(they tell me). It also keeps the gas bill down. Just like people plants like warm feet and cool heads. The reason for the depth of the tube is simply for even plant growth. I believe the tubes are 12" apart. If you have a cool spot you can actually see it in the foliage growth. By adding depth of heating tube the heat which comes up in a V pattern will overlap the adjoining tube heat. That was the theory- and it works. Keep in mind that Pex doesn't like sun and must be protected from direct UV.
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