In article ,
Kay Lancaster wrote:

Bench heating, aka root zone heating.
http://preview.tinyurl.com/yz7qnq5
http://preview.tinyurl.com/ykt425d
http://preview.tinyurl.com/yjpwdfy

which are the long, fractured URLs below:

http://www.rngr.net/Publications/fnn...rsery-notes-2/
2007-winter-forest-nursery-notes/root-zone-heating-can-save-energy-by-
reducing-needs/file


http://www.hrt.msu.edu/energy/Notebo...nderbench_Heat
ing_Systems_by_Bartok.pdf

http://www.umass.edu/umext/floricult...reenhouse_mana
gement/jb_root_zone_heat.htm

Sorry, I haven't looked at the links above, you don't get better than
Kay Lancaster, but let me just say that if the flames on this propane
heater come to a blue tip and not just a billowing cloud of flame, there
is no chance, that I can see, that CO would be a problem.
--
³When you give food to the poor, they call you a saint. When you ask why the poor have no food, they call you a communist.²
-Archbishop Helder Camara

http://tinyurl.com/o63ruj
http://countercurrents.org/roberts020709.htm