Modine HD100 Hot Dawg Power-Vented Natural Gas Unit Heater - 100,000 BTU, 115V, Aluminized Steel

Ceiling-Mounted 100,000 BTU Natural Gas Unit Heater For Large Garages, Workshops, Warehouses, And Commercial Spaces

The Modine HD100 is where the Hot Dawg lineup steps into serious commercial territory. At 100,000 BTU input and 82,000 BTU output (82% efficiency), it moves to a larger chassis (31 x 35.5 x 20.5 inches) and 4-inch venting, both up from the HD60/HD75's smaller frame and 3-inch vent. It pushes 1,490 CFM with a 50°F temperature rise and throws heat 42 feet.

The HD100 shares its chassis with the HD125 and offers optional two-stage ignition for fuel savings in mild weather. It weighs 125 lbs and mounts up to 12 feet high. If you are stepping up from an HD75, note the larger footprint and the change from 3-inch to 4-inch venting, which requires a different vent pipe.

Quick Specs

• BTU Input: 100,000
• BTU Output: 82,000 (82% efficiency)
• Airflow: 1,490 CFM at 70°F
• Supply Voltage: 115V, 1-Phase, 60 Hz
• Vent Size: 4 inch
• Maximum Mounting Height: 12 ft
• Heat Throw: 42 ft at max mounting height
• Dimensions: 31 x 35.5 x 20.5 inches
• Weight: 125 lbs

Key Features

• 100,000 BTU with 1,490 CFM: 33% more BTU and 28% more airflow than the HD75. Handles large garages, workshops, and mid-size commercial spaces.
• Larger chassis, 4-inch venting: The HD100 steps up to a 31 x 35.5 x 20.5-inch chassis and 4-inch vent pipe. This is a different frame than the HD60/HD75 (25 x 26.8 x 18, 3-inch vent). Plan for the larger footprint and vent size if upgrading.
• Two-stage ignition available: Low-fire runs quieter and uses less fuel on moderate days. High-fire delivers full 100,000 BTU in deep cold. Available on HD75, HD100, and HD125.
• 42-foot heat throw from 12 feet: Reaches the far end of large open spaces. The 50°F temperature rise is the highest in the HD series.
• Power-vented exhaust: Built-in power venter pushes combustion gases outdoors through 4-inch venting. No chimney required.
• 10-year heat exchanger warranty: Aluminized steel tubular design standard. 409 stainless steel available for greenhouses and corrosive environments.
• Converts to propane: Ships natural gas. Modine kit #53080 converts to LP. Note: the HD100 uses a different LP kit than the HD75 (#53079).
• Cold climate rated: Starts reliably down to -40°F. ETL certified for residential, commercial, and industrial use in the US and Canada.

Modine HD100 Natural Gas Unit Heater Specifications

Available Options

Fuel Type:

• Natural Gas (standard)
• Propane (via conversion kit #53080, or factory-configured)

Ignition Type:

• Single-Stage, Direct Spark Ignition, 100% Shut-Off with Continuous Retry (standard)
• Two-Stage, Direct Spark Ignition (optional). Available on HD75, HD100, and HD125 only.

Heat Exchanger Material:

• Tubular, Aluminized Steel (standard)
• Tubular, 409 Stainless Steel (optional, for high-corrosion environments)

Performance Overview

The HD100 moves 1,490 CFM with a 50°F temperature rise, the highest air temperature rise in the HD series. From 12 feet, it throws heat 42 feet. It delivers 33% more BTU than the HD75 (100,000 vs 75,000) and 28% more airflow (1,490 vs 1,160 CFM). It shares its chassis with the HD125, so if you need more capacity later, the HD125 fits the same mounting points.

Included Accessories

• Angle mounting brackets, slotted for 16" or 24" joist centers
• Adjustable front-discharge louvers
• Built-in power venter assembly
• Installation and service manual

Not included (sold separately):

• Vent pipe and fittings (4-inch diameter required)
• Thermostat (any standard 24V thermostat)
• LP conversion kit (Modine #53080)
• Gas supply piping and shutoff valve

Applications

• Large garages (4+ car) and detached workshops
• Mid-size warehouses and distribution storage
• Auto repair shops and multi-bay service stations
• Greenhouse heating and agricultural buildings
• Retail stockrooms and commercial back-of-house areas
• Loading docks, maintenance bays, and industrial work areas

Installation Tips

• New chassis size. The HD100 is 31 x 35.5 x 20.5 inches, significantly larger than the HD75 (25 x 26.8 x 18). If replacing an HD75, verify your ceiling framing can accommodate the wider, deeper unit.
• 4-inch vent pipe required. The HD100 steps up from the 3-inch vent used on HD30 through HD75. Existing 3-inch vent pipe will not work. Plan for 4-inch vent materials.
• 12-foot max mounting height. Lower than the HD75 (14 ft). Confirm your intended mount height is within range.
• LP kit is model-specific. The HD100 uses Modine #53080, not #53079 (HD75) or #53079 (HD30-HD60). Do not interchange.
• Clearances: 1 inch top and non-access side. 18 inches on the access side and rear. 4 inches from vent connector.

Buy the Modine HD100 Hot Dawg Natural Gas Unit Heater Online from Cleanflow

The HD100 is the first Hot Dawg to move into the large-chassis, 4-inch-vent tier. It handles spaces the HD75 cannot reach, and shares its frame with the HD125 for future upgradability. Cleanflow stocks the HD100 with free shipping on orders over $199 CAD across Canada and the USA. As an authorized Modine supplier, Cleanflow backs every unit with manufacturer warranty support. 

Not the right fit? Cleanflow offers hassle-free returns and exchanges on all orders.

Frequently Asked Questions

How does the HD100 compare to the HD75?

The HD100 delivers 33% more BTU (100,000 vs 75,000) and 28% more airflow (1,490 vs 1,160 CFM). It uses a larger chassis (31 x 35.5 x 20.5 vs 25 x 26.8 x 18 inches) and requires 4-inch venting instead of 3-inch. Max mounting height drops to 12 feet (vs 14 on HD75). The HD100 weighs 125 lbs vs 85. If you are upgrading from an HD75, you will need a new vent pipe and may need to reframe the mounting.

What vent size does the HD100 require?

4-inch diameter. This is a step up from the 3-inch vent used on the HD30 through HD75. If replacing a smaller Hot Dawg model, the existing 3-inch vent pipe will not work.

Can the HD100 run on propane?

Yes. Ships natural gas. Converts to propane with Modine kit #53080. This kit is specific to the HD100. Do not use kits from other models.

Does the HD100 offer two-stage ignition?

Yes. Two-stage is optional on the HD75, HD100, and HD125. Low-fire saves fuel on moderate days and reduces temperature swings. High-fire delivers full 100,000 BTU in deep cold.

Is the HD100 good for cold climates?

Yes. Rated for startup down to -40°F. ETL certified for residential, commercial, and industrial use in the US and Canada. CSA-B149.1 compliant.