Greenhouse floor - radiant tubes in sand?

Therese

I am considering putting radiant floor heat in my greenhouse, under the paver stones of the floor. The tubing would be buried in a bed of sand, with the paver stones on top. Would this heat the sand? Any comments?

Mark Eatherton

Sand makes an excellent insulator....

Ever been to he beach on a nice sunny day. In your bare feet, when you try and walk on the sand, you get a REAL hot foot. Wiggle your toes a couple of inches below the surface, and feel immediate relief.



With that said, sand CAN be a decent conductor of heat, if the sand is wet and conductive. If it is dry, it will act more like an insulator.



I have done snowmelt systems in sand beds, with pavers placed on top, and initially, during a snow event, the system worked rather poorly. Once some moisture got down and into the sand, it picked up and melted the snow very well.



Instead of doing that, consider a concrete slab, with the tube embedded in the concrete, and set your stone pavers in a wet bed of mortar avoiding any air pockets.



JMHO



ME

Mark Eatherton

By the way...

Are you trying to make the HUMANS comfortable or the PLANTS comfortable??



No sense in heating the floor if the root zones are your target.... Unless you will be propogating plants on the floor.



ME

Therese

Plants

For the plants/seedlings. The idea is to capture solar heat during the day to heat the floor/sand, which would theoretically release heat during the cool night. The greenhouse is in the north where the night temps dramatically drop year-round.

Mark Eatherton

You should be OK...

Plants won't complain if they're a little chilly, so long as you don't freeze their little petals off :-)



I think it would be a good idea energy conservation wise, to use a floor temperature sensing control as opposed to the conventional air sensing thermostat.



I'd also recommend the sensor be high in the floors vertical profile to reflect solar gain.



ME