Choosing The Right Indirect Gas Fired Heater means balancing heat output, venting type, installation needs, and space coverage. Below is a quick product summary to help you compare features at a glance.
| Product | Type / Notable Feature | Max BTU / Coverage |
|---|---|---|
| Modine Hot Dawg, Gas Fired Unit Heater | Low Profile Unit Heater / Indirect-Style Installation | 125,000 BTU |
| Mr. Heater Big Maxx MHU80NG | Natural Gas Unit Heater / Category 1 vertical & Category 3 horizontal venting | 80,000 BTU / ~2000 sq. ft. coverage (manufacturer) |
| Mr. Heater Big Maxx MHU50NG | Natural Gas Unit Heater / Powered Exhaust Venting | 50,000 BTU / ~1250 sq. ft. coverage (manufacturer) |
| Dyna-Glo IR30NMDG-1 Infrared Wall Heater | Infrared Wall Heater / Radiant Heat To Objects | 30,000 BTU / up to 1,000 sq. ft. |
| ProCom MN300TPA-B Infrared Space Heater | Infrared Natural Gas Heater With Thermostat | 30,000 BTU / up to 1,400 sq. ft. |
Modine Hot Dawg, Gas Fired Unit Heater, 125000 BTU
The Modine Hot Dawg is a commercial-style low profile unit heater suitable for large open spaces such as warehouses, workshops, and garages. The listing identifies it as a natural gas fired unit heater, and Modine’s Hot Dawg family is designed for robust, continuous operation.
Features referenced include the unit’s low profile design and its status as a natural gas-fired unit heater. The physical layout allows ceiling or wall mounting where ceiling clearance or layout constraints exist. Its high BTU output (125,000 BTU) is appropriate for heating large volumes or high-ceiling spaces where indirect-style distribution via ducting or louvers can be used.
Installation considerations for this style include proper venting, gas supply sizing, and certified installer requirements. The Hot Dawg family is commonly paired with distribution louvers or ducting to direct warm air where needed. For spaces requiring separation of combustion air, a properly installed flue/vent and fresh-air intake will meet indirect-style safety and ventilation objectives.
Mr. Heater F260560 Big Maxx MHU80NG Natural Gas Unit Heater
The Mr. Heater Big Maxx MHU80NG is a high-capacity gas unit heater intended for large workspaces. The product listing highlights an 80,000 BTU output and coverage up to approximately 2,000 sq. ft. Manufacturer notes include dimensions and electrical requirements for fan operation.
Key features include inclusion of angle brackets and a liquid propane conversion kit with purchase, though the listing specifies natural gas use by default. The unit supports Category 1 vertical and Category 3 horizontal venting, enabling flexible venting strategies for direct or semi-indirect setups depending on installation constraints.
Performance specs include a 120 V fan motor with low amp draw, minimum clearance requirements, and recommendation for professional installation. For spaces where combustion products must be vented outdoors, the Big Maxx’s venting categories and powered exhaust capability make it compatible with indirect-style installations that keep combustion airflow separate from occupied space.
Mr. Heater F260550 Big Maxx MHU50NG Natural Gas Unit Heater
The MHU50NG is a mid-range unit heater from Mr. Heater offering 50,000 BTU per hour and coverage up to about 1,250 sq. ft. The listing emphasizes its powered exhaust that supports both vertical and horizontal venting, enabling tailored exhaust routing to meet building layout and code requirements.
Features called out include outside access to the thermostat and A/C terminals and accessible gas connection points. The unit’s powered exhaust fan simplifies vent termination and can help when routing exhaust to an exterior wall or through a roof.
For indirect-style installations where combustion products must not mix with indoor air, the MHU50NG’s venting flexibility and externalized controls can simplify installation and maintenance. It’s often selected for medium-sized garages or workshops where a centralized vented solution is preferred over unvented radiant heaters.
Dyna-Glo IR30NMDG-1 30,000 BTU Natural Gas Infrared Wall Heater
The Dyna-Glo IR30NMDG-1 is an infrared wall-mounted natural gas heater that provides 30,000 BTU and uses radiant heating to warm objects and people directly. The listing notes it is Natural Gas Ready and highlights the infrared heating method that heats by radiation similar to sunlight.
Infrared models heat objects and surfaces rather than relying solely on air circulation, which can be efficient in drafty or high-ceiling spaces where convective heat dissipates. The listing specifies up to 1,000 sq. ft. coverage under typical conditions.
While not an indirect combustion heater in the traditional sense, infrared wall heaters that vent outdoors or are installed in a way that keeps combustion separate can serve similar needs—targeted warmth without relying on heating the entire volume of air. Verify venting and installation requirements for any project requiring separation of combustion byproducts from living or working areas.
ProCom MN300TPA-B Ventless Natural Gas Infrared Space Heater With Thermostat
The ProCom MN300TPA-B is an infrared natural gas space heater with thermostat control, offering up to 30,000 BTU and coverage claims up to 1,400 sq. ft. The product emphasizes a slim modern profile, multiple thermostat settings, and wall or floor mount flexibility.
Key features include High/Medium/Low thermostat control and a compact infrared design suitable for residential or small commercial spaces. The listing highlights that it is designed for reliable operation with included mounting hardware.
Note that this ProCom model is a ventless infrared heater. Ventless units do not exhaust combustion byproducts outdoors, so they are not a substitute for indirect or vented systems when code or indoor-air-quality concerns require separation of combustion gases. Use ventless units only where allowed by local codes and where ventilation and oxygen depletion safety measures are appropriate.
Buying Guide: Choosing An Indirect Gas Fired Heater
Selecting a heater for a workshop, garage, or commercial space requires careful attention to venting, BTU output, coverage, and safety. Below are the key considerations to compare across the products above and other models you review.
1. Vented Versus Ventless
- Vented/Indirect-Heated Systems: Exhaust combustion gases outdoors; required when building codes or indoor air quality mandate separation of combustion byproducts from occupied spaces.
- Ventless/Unvented Heaters: Offer high efficiency but release combustion products indoors; suitable only where local codes permit and where ventilation/oxygen-safety devices are in place.
2. Heat Output And Space Sizing
- Match BTU output to the cubic volume of the area, not just floor area—high ceilings increase volume and heat loss.
- Manufacturer coverage figures are guidelines; factors such as insulation, doors, and air infiltration affect real-world performance.
3. Venting Requirements And Flexibility
- Look for units that support horizontal and vertical venting options if your site limits roof or wall penetrations.
- Fans or powered exhaust can make routing easier but require electrical power and affect installation cost.
4. Combustion Air Management
- Indirect systems often supply combustion air from outdoors or via sealed intakes to avoid drawing indoor air for combustion.
- Verify whether the unit requires dedicated combustion air, and plan intake locations to comply with code.
5. Installation And Clearance Needs
- Check minimum clearances from floor, walls, and combustibles. Ceiling-mount models reduce floor footprint but need adequate overhead space.
- Professional installation by a licensed HVAC or gas contractor ensures safe fuel connections, venting, and controls.
6. Controls, Thermostat, And Operation
- Thermostat integration and remote access can improve comfort and efficiency in intermittent-occupancy spaces.
- Variable fan speeds, ignition type, and conversion kit availability (natural gas vs LP) increase flexibility.
7. Efficiency And Heat Distribution Type
- Infrared / Radiant Heaters: Heat objects directly and are effective in drafty, open, or high-ceiling environments for localized comfort.
- Unit Heaters With Fans: Move warm air around large spaces; suitable when even air distribution is needed.
8. Safety Features
- Look for oxygen depletion sensors, flame supervision, and automatic shutoff where applicable.
- Confirm compliance with relevant safety standards (ANSI, CSA, etc.) and local code requirements.
9. Fuel Type And Conversion Options
- Ensure the chosen model supports your available fuel (natural gas vs LP). Conversion kits may be offered but confirm compatibility and professional conversion.
10. Maintenance And Serviceability
- Access to controls, burners, and vent connections simplifies servicing. Units with exterior access panels can reduce maintenance time.
- Inspect vents, flue paths, and combustion air intakes periodically and follow manufacturer maintenance intervals.
Comparison Perspectives
- Large Volume / Warehouse: High-BTU unit heaters with dedicated venting and distribution louvers (Modine Hot Dawg, Mr. Heater Big Maxx) are often best.
- Medium Garage / Workshop: Mid-range unit heaters with powered exhaust and flexible venting (MHU50NG, MHU80NG) can balance cost and performance.
- Targeted Warmth / Localized Comfort: Infrared wall heaters and compact units (Dyna-Glo IR30NMDG-1, ProCom MN300TPA-B) suit spot heating needs but verify venting strategy and code compliance.
Before purchasing, document the space dimensions, ceiling height, insulation level, intended mounting location, and local venting/code constraints. Share those details with a qualified installer to select the correct capacity, venting type, and controls for a safe and effective installation.