Quick Summary: This guide reviews five gas-powered heaters suitable for garages, workshops, sheds, and other semi-enclosed spaces. Each selection highlights fuel type, mounting style, and key performance specs to help compare BTU output, coverage, and installation considerations.
| Product | Fuel Type | BTU | Coverage / Notes |
|---|---|---|---|
| Mr. Heater Big Maxx MHU80NG | Natural Gas | 80,000 BTU | Coverage ~2000 sq. ft.; includes LP conversion kit |
| Mr. Heater MHU80LP Propane Unit Heater | Propane | 80,000 BTU/Hr | Advertised up to 1000 sq. ft.; ceiling mount brackets included |
| Dyna-Glo IR30NMDG-1 Infrared Wall Heater | Natural Gas | 30,000 BTU | Infrared radiant heat, up to 1000 sq. ft. |
| Modine Hot Dawg Gas Fired Unit Heater | Propane | 75,000 BTU Input | Power-vented garage unit; 80% efficient |
| Mr. Heater Portable 4000–18000 BTU LP Unit | Propane | 4,000 / 9,000 / 18,000 BTU | Portable use, up to 450 sq. ft.; three heat settings |
Mr. Heater Big Maxx MHU80NG
This natural gas unit heater delivers 80,000 BTU and is specified to cover approximately 2,000 sq. ft. The package lists two angle brackets and a liquid propane conversion kit, while thermostat, hose, and regulator are not included. The unit dimensions are 29.33” L x 15.50” W x 26.37” H, and it requires a minimum 8 ft. clearance from the floor to the base of the unit for safe operation.
Venting is specified as category 1 vertical and category 3 horizontal, which affects whether the heater can use existing flue systems or requires different venting components. Electrical draw is low (2.3 amps, 120 V) for controls and ignition. These listed features indicate suitability for larger garages or medium commercial spaces where a natural gas supply and proper venting are available.
Mr. Heater MHU80LP Propane Unit Heater
The MHU80LP is the propane variant of an 80,000 BTU unit heater intended for ceiling or wall mounting. Manufacturer features include a spark ignition system with a self-diagnostic control module and two angle brackets to simplify ceiling-mount installation.
Listed performance notes indicate it can heat up to 1,000 square feet, making it a common choice for detached garages, small workshops, and barns where propane is the preferred fuel. The spark ignition and diagnostic features are relevant for reliability and troubleshooting during installation and service.
Dyna-Glo IR30NMDG-1 Infrared Wall Heater
The Dyna-Glo IR30NMDG-1 is a 30,000 BTU infrared wall heater designed to radiate heat to objects and people rather than primarily heating the air. This infrared technology can feel faster and more direct, similar to sunlight, and is noted as natural gas ready (fuel conversion not permitted).
Manufacturer claims up to 1,000 sq. ft. coverage and emphasizes radiant heat distribution. Infrared style heaters can be effective in spaces where air movement is limited or when targeted warmth is preferred for work areas, benches, or localized zones.
Modine Hot Dawg Gas Fired Unit Heater
The Modine Hot Dawg is a commercial-style gas-fired unit heater offered as a propane model with 75,000 BTU input and ~80% combustion efficiency. It’s described as power vented, which allows venting through an exhaust fan and flexible venting options in constrained spaces.
Power-vent models like this can simplify vent routing compared with traditional atmospheric-vent units, and Modine’s Hot Dawg family is commonly specified for garages, shop bays, and light industrial spaces where continuous or high-duty heating is required.
Mr. Heater Portable 4000–18000 BTU Unit
This Mr. Heater portable LP unit provides variable settings at 4,000, 9,000, and 18,000 BTU, with a listed heat range up to 450 sq. ft. It supports dual tank connection for longer run time with larger tanks and uses a piezo sparking mechanism.
Features include automatic safety shutoff on tip-over and portability for temporary or spot heating. While not a fixed unit heater, this model is relevant when evaluating small-space gas heating options where a permanent unit is not feasible or when localized supplemental heat is needed.
Buying Guide: How To Choose A Gas Unit Heater
Selecting the right gas unit heater requires matching BTU output, fuel type, venting, and mounting style to the space. This guide outlines key factors and comparison points to consider before purchase or installation.
1. Determine Required BTU And Coverage
Calculate heat load based on space volume, insulation, door openings, and local climate. As an approximate baseline, 40–60 BTU per sq. ft. is often cited for colder climates or poorly insulated spaces. Compare unit BTU ratings to your calculated requirement and consider zoning or multiple smaller units for even distribution.
2. Fuel Type: Natural Gas Vs. Propane
Natural gas units require piped gas service but can be economical for continuous use. Propane offers flexibility where piped gas is unavailable; tanks or bulk supply are needed. Verify conversion kit availability if you might switch fuels later.
3. Venting And Installation Type
Venting options include category 1 (atmospheric), category 3 (direct vent), and power vented systems. Power-vent units can simplify vent routing; direct venting can improve combustion air quality. Confirm local code requirements and whether existing flues can be used.
4. Mounting And Clearance Requirements
Unit heaters are typically ceiling-mounted or wall-mounted. Check listed minimum clearances (e.g., an 8 ft. floor clearance specified for some models). Angle brackets or mounting hardware may be included; otherwise plan for professional installation.
5. Ignition, Controls, And Thermostat Compatibility
Ignition systems vary from continuous pilot to electronic spark or intermittent pilot. Electronic ignition with a self-diagnostic control module can simplify troubleshooting. Determine if the unit accepts a conventional thermostat or needs specific control interfaces.
6. Heat Distribution: Infrared Vs. Convective
Infrared (radiant) heaters heat objects and people directly, performing well in drafty or high-ceiling spaces for targeted warmth. Convective/forced-airunit heaters distribute warm air and are better for whole-space warming. Match the technology to the use case.
7. Efficiency And Operational Costs
Compare input BTU to useful output and listed efficiency ratings where available. Higher efficiency reduces fuel consumption but may increase initial cost. Consider duty cycle and runtime to estimate operating cost between natural gas and propane.
8. Safety Features
Look for tip-over shutoff on portable units and safety switches, flame rollout protection, and overheat limits on fixed units. Verify proper clearances and ensure carbon monoxide safety measures when installing indoor gas appliances.
9. Maintenance And Serviceability
Regular maintenance includes cleaning combustion chambers, checking ignition components, and verifying vent integrity. Choose units with accessible service panels and consider manufacturer support and replacement part availability.
10. Noise And Air Movement
Forced-air unit heaters and power-vent models may produce more operational noise than infrared units. Assess whether noise is acceptable for the work environment and whether deflection louvers are needed to control airflow direction.
11. Portability Versus Permanent Installation
Portable propane heaters offer flexibility for occasional or temporary use but require careful ventilation and fuel management. Permanently installed gas unit heaters provide higher output and integrated venting for continuous use in workshops and garages.
12. Compliance And Permitting
Gas heater installation may require permits, code compliance, and inspections. Confirm local building and fuel-gas codes, and factor in professional installation costs when evaluating total project needs.
13. Comparing Multiple Perspectives
- Performance Perspective: High-BTU fixed units are best for whole-space heating; infrared units are best for targeted warmth.
- Cost Perspective: Natural gas tends to be cheaper per BTU for high-duty applications; propane suits locations without gas service.
- Installation Perspective: Power-vent and direct-vent units may reduce chimney modifications; atmospheric units may require existing flue infrastructure.
- Safety Perspective: Fixed units with proper venting reduce indoor combustion risks compared with indoor use of portable unvented heaters.
14. Final Selection Checklist
- Confirm space size and calculate BTU need.
- Choose fuel type and verify supply availability.
- Determine venting method and check clearances.
- Decide on radiant versus convective heating based on use.
- Verify compatible controls, safety features, and maintenance plan.