1500W / 5100 BTU. It comfortably holds frost off a 6×8 to 8×12 ft greenhouse, a small sunroom, a shed or a grow tent. Bigger, drafty or single-wall poly spaces want a second unit. It's a frost-protection heater, not a whole-barn furnace, and we'd rather tell you that now.

Plug the heater into the included digital controller, push the probe into the soil or clip it near your plants, press SET and pick a temperature. When the reading drops below it the heater switches on; when it climbs back over, it switches off. The dial on the heater itself is a coarse backup — the controller is the one you'll actually use.

That's the whole job. PTC ceramic self-limits so the element can't run away, there's no exposed glowing wire behind the grille, and the thermostat cycles it off every time the target is met. Keep it on a flat surface off wet floors, give the intake a foot of clearance, and use a 14-gauge or heavier extension cord if you need one. It's dust-rated (IP20), not splash-rated, so keep it clear of misters.

On the 800W setting, about 14¢ an hour at the US average rate of 17¢ per kWh, and only while the thermostat is calling for heat. Most frost nights need a few hours of actual run time, not eight. Full 1500W is there for the nights that need it.

Yes — that's one of the most common places it ends up. Set the probe at plant height, run it on 800W, and switch to fan-only mode in summer to keep air moving without adding heat.