Best Propane Heater With Thermostat for Greenhouse Spaces

Greenhouse heating needs reliable temperature control to protect plants from cold stress. Below is a concise comparison of five propane heaters with built-in thermostats or thermostat control suitable for greenhouse use. This guide focuses on heating capacity, thermostat features, safety systems, and mounting options to help you match a unit to your greenhouse size and ventilation needs.

Product	Type	BTU Range	Thermostat
Mr. Heater MHVFGH30LPBT	Vent-Free Blue Flame	Up To 30,000	Built-In Thermostat
Mr. Heater MHVFBF20LPT	Blue Flame Wall	Up To 20,000	Built-In Thermostat
Mr. Heater F299730	Blue Flame Wall	Up To 30,000	Built-In Thermostat
ProCom ML300TBA-B	Ventless Blue Flame	Up To 30,000	Thermostat Control
ProCom ML100TPA-B	Infrared Compact	Up To 10,000	High/Med/Low Thermostat

Mr. Heater MHVFGH30LPBT 30,000 BTU Vent Free Heater

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This vent-free blue flame propane heater delivers up to 30,000 BTU, designed to heat large greenhouse volumes up to roughly 1,000 sq. ft. The unit includes a built-in thermostat for accurate temperature regulation and a battery-powered electronic ignition for easy startup. Fuel consumption and run time are specified by the manufacturer, and the heater is rated to operate reliably at elevations up to 4,500 ft.

Key safety and operational features listed include an Oxygen Depletion Sensor (ODS) that automatically shuts the unit off if oxygen levels drop below a safe threshold. The vent-free design convects heat into the air, which can be effective for greenhouse spaces with controlled ventilation. Consider greenhouse ventilation plans and CO monitoring when using vent-free propane units.

Mr. Heater MHVFBF20LPT 20,000 BTU Blue Flame Wall Heater

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The 20,000 BTU wall-mounted blue flame model is sized for smaller greenhouses up to about 700 sq. ft. It features an integrated thermostat for maintaining setpoint temperatures and a battery-powered electronic ignition for straightforward operation. The specified fuel consumption and thermal output allow predictable heat delivery for modest greenhouse volumes.

Safety is emphasized by the built-in Oxygen Depletion Sensor (ODS), which is standard on indoor propane units. The wall-mount format frees floor space and positions the heater for even convective distribution. For greenhouse use, ensure placement avoids direct heat on delicate plants and allows appropriate airflow to prevent hot or cold pockets.

Mr. Heater F299730 30,000 BTU Blue Flame Vent Free Wall Heater

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This 30,000 BTU blue flame wall heater offers similar capacity to the MHVFGH30LPBT but in a wall-mounted configuration optimized for residential and auxiliary spaces. The unit includes a thermostat, electronic ignition, and standard safety features such as ODS and CSA certification for indoor operation.

Blue flame vent-free heating convects warm air into the greenhouse, which is effective where even indoor air warming is desired. The manufacturer notes performance consistency at elevations up to 4,500 ft. When integrating this heater into greenhouse systems, pair it with ventilation and carbon monoxide monitoring to maintain plant and human safety.

ProCom ML300TBA-B Ventless Blue Flame Space Heater 30,000 BTU

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The ProCom ML300TBA-B is a ventless 30,000 BTU blue flame unit listing thermostat control and multiple mounting options. It is rated to heat large indoor areas and emphasizes an adjustable thermostat for maintaining greenhouse temperature setpoints.

Manufacturers of ventless blue flame units note efficient heat transfer by warming the air directly, making these models effective in enclosed greenhouse structures. Safety features common to ventless propane heaters should be implemented, including monitoring oxygen and carbon monoxide levels and ensuring proper propane supply connections by a qualified installer.

ProCom ML100TPA-B Ventless Infrared Propane Heater 10,000 BTU

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The ProCom ML100TPA-B is a compact infrared propane heater producing up to 10,000 BTU, suited for small greenhouses, propagation areas, or localized heating near plant benches. Infrared technology warms objects and surfaces rather than only the air, which can reduce stratification and provide gentle root-zone warmth.

This unit lists High/Medium/Low thermostat control, wall-mount and floor-base installation options, and portability. Infrared heating can be advantageous in greenhouses where targeted warmth is preferred and where vent-free operation is compatible with greenhouse ventilation and air-quality plans.

Buying Guide: Key Considerations For Greenhouse Propane Heaters

Selecting an appropriate propane heater with thermostat for a greenhouse involves several technical and practical considerations. Below are the core factors to evaluate before purchase and installation.

Heating Capacity And Greenhouse Size

• BTU Rating: Match heater BTU output to greenhouse volume, construction R-value, and desired temperature rise. As a rough estimate, 10,000 BTU may suit small propagation areas up to 500 sq. ft., while 20,000–30,000 BTU units serve larger spaces up to 1,000 sq. ft. depending on insulation.
• Multiple Units: For even heat distribution, multiple smaller units can reduce cold spots compared to a single large heater.

Thermostat Accuracy And Control Options

• Built-In Thermostats: Provide integrated automatic setpoint control and reduce the need for separate controllers.
• External Sensors: Consider units compatible with remote probe sensors or external thermostats for placing the sensor at plant canopy height rather than by the heater.
• Control Granularity: Look for thermostats that allow precise temperature bands and cycling behavior suitable for plant tolerance.

Heating Method: Blue Flame vs Infrared

• Blue Flame / Convective: Heats the air, creating uniform ambient temperature. Effective for whole-space heating and general greenhouse environments.
• Infrared (Radiant): Heats objects and plant surfaces directly, which can be more efficient for targeted zones and reducing air stratification.
• Choose Based On Use: Use blue flame for whole-structure warming; choose infrared for bench-level propagation or spot heating sensitive plants.

Vent-Free Operation And Air Quality

• Vent-Free Considerations: Many propane greenhouse heaters are vent-free to maximize efficiency, but vent-free combustion releases water vapor and combustion byproducts into the greenhouse air. Plan ventilation and humidity management accordingly.
• Oxygen Depletion Sensor (ODS): Ensure ODS is included — it shuts down the unit when oxygen is too low, which is critical for occupant safety and plant environments.
• CO Monitoring: Install carbon monoxide detectors rated for greenhouse use and follow local codes on indoor combustion appliance use.

Installation, Mounting, And Placement

• Mounting Type: Wall-mounted units save floor space; floor-mounted or portable units may be repositioned for propagation benches.
• Clearances: Follow manufacturer clearance specifications to combustibles and ensure heat is not concentrated on plant surfaces unless intended.
• Professional Installation: For hard-piped propane or permanent installations, use a licensed technician to ensure safe fuel connections and compliance with local codes.

Safety Features And Certifications

• ODS And Auto Shutoff: Essential for indoor propane use.
• CSA Or Equivalent Certification: Look for recognized safety certifications indicating third-party testing.
• Elevation Ratings: Confirm operational elevation range; output and combustion characteristics can change at high altitudes.

Humidity, Condensation, And Plant Health

• Moisture Effects: Vent-free combustion produces water vapor; monitor humidity to prevent fungal issues and condensation on glazing.
• Dehumidification And Airflow: Pair heating with exhaust or dehumidification strategies if humidity rises above plant-appropriate ranges.

Energy Efficiency And Fuel Logistics

• Fuel Consumption: Compare expected hours-per-tank and consumption rates at typical setpoints for greenhouse cycles.
• Refill Or Bulk Supply: Plan propane supply logistics for remote greenhouses or extended cold periods.

Redundancy And Zoning

• Multiple Zones: For larger greenhouses, use zoned temperature control so different plant groups maintain optimal ranges.
• Backup Heat: Consider a secondary heater or electrical backup for prolonged extreme cold or propane supply interruptions.

Comparison Perspectives

• Performance Perspective: Blue flame vent-free units provide strong whole-space heating; infrared units provide surface-level radiant heat better for propagation.
• Safety Perspective: All indoor propane heaters should include ODS; vent-free units require more air-quality planning than vented systems.
• Operational Perspective: Built-in thermostats simplify control, but remote sensors improve accuracy at plant canopy height.