Best Gas Heater for Greenhouse: Efficient Gas Heating Options

Quick Overview: Choosing the right gas heater for a greenhouse balances heat output, fuel type, ventilation needs, and safety features. The table below summarizes the five gas heaters selected for greenhouse use, emphasizing BTU range, fuel type, and notable safety or control features to help narrow options quickly.

Product	Fuel Type	Max BTU	Key Feature
Mr. Heater MHVFBF20LPT	Propane (Vent Free)	20,000	ODS Safety Shut-Off, Thermostat
Dyna-Glo IR30NMDG-1	Natural Gas (Infrared)	30,000	Infrared Radiant Heat, Heats Objects Directly
ProCom MN300HBA-B	Natural Gas (Ventless)	30,000	Manual Controls, ODS Included
Mr. Heater MHVFBF30NGT	Natural Gas (Vent Free)	30,000	Thermostat, Efficient Blue Flame
Mr. Heater Big Maxx MHU80NG	Natural Gas (Unit Heater)	80,000	High Capacity, Venting Options

Mr. Heater MHVFBF20LPT 20,000 BTU Blue Flame Vent Free Propane Heater

Check Price on Amazon

This vent-free propane wall heater provides up to 20,000 BTUs, appropriate for small to medium greenhouse spaces where propane is the preferred fuel. It includes a thermostat for temperature regulation and a battery-powered electronic ignition for straightforward startups. Fuel consumption is specified at 0.926 lbs per hour, which helps estimate runtime from a given tank capacity.

Safety is supported by a factory-standard Oxygen Depletion Sensor (ODS) that automatically shuts off the unit if oxygen levels fall below safe thresholds. The unit is rated to operate reliably up to 4,500 ft elevation. As a vent-free heater, it releases combustion products into the greenhouse; consider ventilation strategies and plant sensitivity to humidity and CO2 when deploying.

Dyna-Glo IR30NMDG-1 30,000 BTU Natural Gas Infrared Wall Heater

Check Price on Amazon

The Dyna-Glo IR30NMDG-1 uses infrared technology to radiate heat directly to plants, benches, and surfaces rather than heating air alone. This method can be efficient in greenhouses because it warms the objects that retain heat and reduces convective losses from openings.

Rated at 30,000 BTU, it is natural gas ready and designed to cover larger greenhouse zones (up to the manufacturer’s stated square footage). Infrared systems may reduce temperature stratification and provide uniform surface warmth, but they require correct mounting and orientation to ensure plants receive even coverage. Fuel conversion is not permitted on this model, so natural gas availability is required.

ProCom Heating MN300HBA-B 30,000 BTU Natural Gas Ventless Blue Flame Heater

Check Price on Amazon

This ventless blue flame heater operates on natural gas and delivers up to 30,000 BTU. It features manual control with three heat settings and a Piezo push-button ignition, which allows operation without electrical supply. The unit includes an Oxygen Depletion Sensor for automatic shut-off in low-oxygen conditions.

Because it’s ventless, combustion byproducts enter the greenhouse environment; this can increase humidity and CO2, which may be beneficial for some crops but requires monitoring. The manual control and three heat settings provide simple staging for heat output, making it suitable for growers who prefer straightforward mechanical controls.

Mr. Heater MHVFBF30NGT 30,000 BTU Vent Free Blue Flame Natural Gas Heater

Check Price on Amazon

The MHVFBF30NGT is a vent-free natural gas wall heater delivering up to 30,000 BTU, suitable for medium to larger greenhouse zones. It includes a thermostat for precise temperature control and an electric ignition powered by an included battery, simplifying automated temperature maintenance.

This model emphasizes fuel efficiency with a blue flame burner designed for even convection heat distribution. As with other vent-free heaters, evaluate indoor air quality implications and ensure proper monitoring of CO2, humidity, and oxygen levels when used in enclosed plant spaces. The unit’s design aims for even area heating rather than directional radiant heat.

Mr. Heater F260560 Big Maxx MHU80NG 80,000 BTU Natural Gas Unit Heater

Check Price on Amazon

The Big Maxx MHU80NG is an industrial-style natural gas unit heater rated at 80,000 BTU, built for larger greenhouses or for growers needing significant airflow and high heat capacity. It includes mounting brackets and is suitable for category 1 vertical or category 3 horizontal venting configurations.

This unit requires electrical power for the built-in fan and uses venting to exhaust combustion products outside the greenhouse, preserving indoor air quality. Its high output and forced-air delivery make it effective for large-volume spaces or situations where rapid temperature recovery is needed. Proper installation with adequate clearances and venting is essential for safe operation.

Buying Guide: Choosing The Right Gas Heater For Your Greenhouse

Selecting the best gas heater depends on greenhouse size, plant species, fuel availability, ventilation capacity, and safety needs. Below are key purchase considerations and comparison perspectives to guide selection.

Heat Output And Sizing

• BTU Requirement: Calculate heat loss for your greenhouse by factoring in square footage, insulation, local winter lows, and desired internal temperature. Small greenhouses may require 10,000–30,000 BTU; larger or poorly insulated spaces need more.
• Overcapacity vs. Cycling: Oversized heaters can short-cycle, increasing wear and uneven humidity. Choose a unit with adjustable settings or thermostat control for better staging.

Fuel Type And Availability

• Natural Gas: Good for fixed installations and continuous use if mains supply is available. Many natural gas units require venting or are designed as vent-free options.
• Propane: Portable and suitable where natural gas is unavailable. Propane vent-free heaters provide flexibility but require propane storage and monitoring of tank levels.
• Conversion Limitations: Some models prohibit fuel conversion—verify fuel compatibility before purchase.

Ventless vs. Vented

• Ventless (Blue Flame): Efficient at heating air and raising CO2/humidity levels, potentially beneficial for plant growth. However, combustion products remain inside, so monitor air quality and oxygen levels and use units with ODS safeguards.
• Vented/Unit Heaters: Exhaust combustion gases outdoors, preserving indoor air quality. Forced-air unit heaters are suitable for larger greenhouses and where venting can be installed.
• Infrared: Radiant heaters warm surfaces and plants directly, which can be efficient in drafty environments where heating air is less effective.

Controls And Automation

• Thermostat Integration: Essential for maintaining consistent setpoints and reducing fuel use. Electronic thermostats with probes provide finer control.
• Manual Controls: Simpler mechanical settings may be adequate for stable climates or as backup to automated systems.
• Remote Monitoring: Consider added sensors for humidity, CO2, and oxygen when using ventless gas heaters in enclosed greenhouses.

Safety Features

• Oxygen Depletion Sensor (ODS): Critical for ventless gas heaters to prevent operation under low-oxygen conditions.
• Automatic Shut-Offs & Tip-Over Switches: Important for portable and mounted units to mitigate fire or combustion risks.
• Overheat Protection: Protects the heater and environment from thermal runaway or malfunction.

Installation And Venting Considerations

• Clearance Requirements: Follow manufacturer minimum clearances from floors, walls, and plants to avoid heat damage.
• Venting Routes: For vented units, plan exhaust routes that prevent re-entry of combustion gases and that comply with local codes.
• Electrical Needs: Some gas heaters require electrical power for fans or ignition; ensure supply and grounding are present.

Plant Impact And Environmental Factors

• CO2 And Humidity: Ventless heaters increase CO2 and water vapor, which can be beneficial for photosynthesis but may also increase disease risk in some crops. Monitor and control humidity accordingly.
• Air Circulation: Ensure even distribution of heat to avoid hot/cold pockets; fans and placement strategy can improve uniformity.
• Altitude And Efficiency: Check manufacturer ratings for altitude limits and efficiency figures—some units are rated for reliable operation up to certain elevations.

Maintenance And Serviceability

• Access For Cleaning: Regular cleaning of burners and sensors ensures consistent performance. Choose models with user-accessible panels if frequent maintenance is anticipated.
• Replacement Parts: Confirm local availability of filters, ignitors, and ODS components to minimize downtime.
• Professional Installation: For vented or high-BTU units, professional installation can ensure code compliance and safe operation.

Comparison Perspectives

• Small Greenhouses: Vent-free propane or smaller natural gas blue flame units with thermostats offer straightforward heat with minimal installation.
• Medium Greenhouses: 20,000–30,000 BTU vent-free or radiant infrared units provide balance between capacity and installation complexity.
• Large Greenhouses: High-capacity unit heaters with venting and forced air (like the Big Maxx) provide robust heat and maintain indoor air quality for large volumes.

When evaluating gas heaters for greenhouse use, weigh heat output, fuel logistics, ventilation strategy, plant needs, and safety systems. Proper sizing, correct mounting, and continuous monitoring yield effective climate control while minimizing risks to plants and people.