Selecting a Greenhouse Heater: Types, Mounting, and Venting

Night temperatures can plummet—greenhouse heaters protect plants. Choose based on structure size, fuel cost, and safety.

Heater Types

• Electric: Best for small greenhouses. Clean, no fumes, no ventilation needed. Precise temperature control.
• Gas (natural/bottled): Less efficient. Combustion fumes require ventilation. Constant monitoring, safe placement essential.
• Paraffin: Basic. Needs refilling, wick trimming. Fumes require ventilation. Reduces frost risk; emergency backup.

Mounting Options

• Hanging: Ceiling-mounted. Saves floor space. Hang high enough.
• Wall: Wall-mounted, vents outside. No floor space. Clear area in front.
• Floor: Freestanding. Uses floor space—disadvantage in tight greenhouses.

Combustion & Venting

• Open combustion: Uses interior air. No flammables near unsealed burner.
• Separated combustion: Uses outside air, sealed burner, exhaust piped out.
• Sealed combustion: Fully sealed, direct vent for intake/exhaust (concentric pipes). No indoor air exchange.
• Vent types: Unvented (temporary only), gravity (vertical), power (blower, flexible), direct (sealed combustion only).

Sizing

Calculate output range (BTUs) based on greenhouse area, climate, and glazing. Consult suppliers or online calculators.

Assess your greenhouse first—then choose the heater that fits.