Best for
A 10x12 or 12x16 twin-wall greenhouse, or a smaller single-glass house, where the heat-loss number lands between 5,000 and 9,500 BTU per hour.
#17 in the buying orderHeatingBuy when needed
Bio Green Phoenix 2800W Greenhouse Heater
The step up when one 1500 W heater is not enough: 9,554 BTU on a 240 V circuit, with a thermostat that runs from minus 58 to 79 degrees F.
- Current price
- $299.99 at biogreen-products.com, down from $329.99
- Checked September 20, 2026
- Review type
- Independent desk review
- Not a physical product test
Skip if
You do not have, and will not install, a 240 V circuit in the greenhouse. On 120 V this heater does not exist as an option.
Hidden cost
The 240 V circuit is the real cost. Running cost is about 51 cents per hour at full duty at the June 2026 US residential electricity rate.
Why it made the list
The buyer case
Two elements of 1000 and 1800 W for 2800 W together, 9,554 BTU, IPX4 splash protection, a wide-range manual thermostat and a two-year warranty, in stock on September 20, 2026. It is the only splash-rated hobby heater we found between a 1500 W plug-in and a gas unit.
Compatibility comes first
240 V, 60 Hz. Bio Green rates it for rooms up to 215 square feet; by extension-service heat-loss math it covers a 12x16 twin-wall house at a 30 degree gap.
Installation boundary
Dedicated 240 V circuit with GFCI protection per NEC 210.8, confirmed with your inspector. Mount low, clear of spray, and pair it with a circulation fan so one heater reaches the far bench.
Our verdict
Buy it once the math says a single 1500 W heater is short, and before you consider two plug-in heaters on separate circuits. For a heated house over 12x16 in a real winter, a vented gas unit is the next step.
Primary sources
Product facts come from these direct sources. They are kept separate from the purchase button, and none is rewritten through an affiliate redirect.
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Canopia Portable Greenhouse Fan Heater 1500W NA
Check a current US distributor
A purpose-built 1500W fan heater is a better fit than an exposed household space heater, but the greenhouse heat-loss math still decides whether it is enough.
- Best for
- Small North American greenhouses needing frost protection on a correctly sized circuit.
- Skip if
- Your heat-loss calculation exceeds the output, the greenhouse has no safe GFCI-protected supply, or you expect a 1500W heater to hold warm-growing temperatures through severe cold.
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Bootstrap Farmer 24V Greenhouse Thermostat
$115.99
This is a proper 24V climate-system thermostat, not a universal plug-in controller for any heater or fan.
- Best for
- A greenhouse heating or cooling system designed for 24V thermostat control.
- Skip if
- You are trying to plug a normal 120V appliance directly into it. That is not what this thermostat is for.
#16Buy when neededHeating
Bio Green Palma 1500W Greenhouse Heater
$149.99 at biogreen-products.com
The default heater for a 6x8 to 8x12 twin-wall greenhouse: 5,120 BTU, a real thermostat, IPX4 splash protection and a two-year warranty on a standard outlet.
- Best for
- Owners of a 6x8 to 8x12 greenhouse who need frost protection or a modest overnight hold on a single GFCI-protected 120 V circuit.
- Skip if
- Your heat-loss math needs more than about 5,000 BTU per hour, you have single glass in a cold climate, or you cannot give it a GFCI-protected outlet of its own.