Modine HD45 Power-Vented Natural Gas Unit Heater — 45,000 BTU, 115V, Aluminized Steel

Modine HD45 Hot Dawg — Power-Vented Gas Heater for Workshops, Garages & Warehouses

Product Overview

The Modine HD45 is a 45,000 BTU power-vented gas unit heater that delivers 50% more heating capacity than the HD30 in the same compact chassis. It mounts just 1 inch from the ceiling, runs on natural gas at 82% thermal efficiency, and exhausts combustion gases safely outdoors through a built-in power venter. At 720 CFM, it heats spaces up to approximately 1,125 sq ft with standard 8-foot ceilings and moderate insulation. 

The HD45 natural gas unit heater is the most popular Hot Dawg model for 2-car garages and mid-size workshops, and it handles cold-weather startup from -40F. Use the Cleanflow BTU Calculator to confirm sizing for your space.

Quick Specs

• BTU Input: 45,000
• BTU Output: 36,900 (82% efficiency)
• Airflow: 720 CFM at 70F
• Supply Voltage: 115V, 1-Phase, 60 Hz
• Vent Size: 3 inch
• Maximum Mounting Height: 10 ft
• Sound Level: 57 dBA at 5 ft
• Approx. Weight: 60 lbs

Key Features

• Power-Vented System: Built-in power venter safely exhausts combustion gases outdoors through 3-inch venting, with flexibility for horizontal or vertical vent runs using the smallest-diameter vent pipe possible.

• Compact, Low-Profile Design: Mounts just 1 inch from the ceiling on included angle brackets, fitting joists on 16-inch or 24-inch centers. Delivers 45,000 BTU from the same 22 x 26.8 x 12.2-inch chassis as the HD30, making it a direct upgrade without additional ceiling space.

• In-Shot Burners: In-shot burners on each heat exchanger tube provide reliable performance, ease of serviceability, and contribute to the low sound level on flame ignition and extinction.

• Quiet Performance: Operates at 57 dBA at 5 feet. In independent testing, the Hot Dawg runs quieter than comparable competitor units at the same BTU rating. Well suited for environments where comfort and low noise matter.

• Durable Heat Exchanger: Aluminized steel tubular heat exchanger resists corrosion and carries a 10-year warranty from Modine. 409 stainless steel is available as an upgrade for higher-corrosion environments.

• Fuel Flexibility: Ships configured for natural gas. Converts to propane using Modine conversion kit #53079. The same burner handles both fuel types.

• Electric Knockouts: Field wiring connections and knockouts for quick access to gas and electrical keep installation costs low and save time on installation and maintenance.

• Reversible Controls: Right or left-hand controls available. Gas, electrical, and flue connections can be changed by flipping the unit over during installation.

• Flexible Mounting Options: Ceiling-mount is standard. Wall configurations are also possible for custom installation layouts.

• Baked Polyester Paint: Neutral-colored, corrosion-resistant finish blends into a wide variety of environments.

• Permanently-Lubricated Motor: A 1/15 HP shaded pole motor is permanently lubricated for trouble-free dependability with no routine motor maintenance required.

• Direct Spark Ignition: Single-stage, 100% gas shut-off with continuous retry eliminates the need for a standing pilot light.

• Adjustable Louvers: Front-discharge louvers direct heated air where it is needed, with a 27-foot heat throw from a maximum 10-foot mounting height.

• Thermal Efficiency: 82% thermal efficiency reduces energy use while maintaining reliable output.

• ETL Certified: ETL/Intertek listed for residential, commercial, and industrial use in the US and Canada. CSA-B149.1 compliant.

• Proudly Designed, Engineered, and Assembled in the USA.

Modine HD45 Gas Unit Heater Specifications

Available Options

The Modine HD45 can be configured with the following options when ordering. The standard HD45AS0111 ships as noted below.

Fuel Type:

• Natural Gas (standard)

• Propane (via conversion kit #53079, or factory-configured)

Ignition Type:

• Single-Stage, Direct Spark Ignition, 100% Shut-Off with Continuous Retry (standard for HD45)

• Note: Two-Stage ignition is available on HD75, HD100, and HD125 models only.

Heat Exchanger Material:

• Tubular, Aluminized Steel (standard)

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

Supply Voltage (HD Series):

• 115V / 1Ph / 60Hz (standard for HD45)

• Additional voltage options (208V, 230V single-phase; 208V, 230V, 460V, 575V three-phase) are available across the HD series. Contact Cleanflow for availability on the HD45 configuration you need.

Performance Overview

The HD45 moves 720 CFM through a 10-inch propeller fan, raising air temperature by 46F and throwing heat 27 feet from a 10-foot mounting height. Outlet velocity is 749 FPM. At 57 dBA measured at 5 feet, the HD45 runs quieter than comparable competitor units at the same BTU rating. The in-shot burner design contributes to smooth, low-noise flame ignition and consistent heat delivery across the aluminized steel heat exchanger tubes.

Construction and Design

Included Accessories

• 1-inch angle mounting brackets (2), 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 (3-inch diameter required)

• Thermostat (compatible with any standard 24V thermostat)

• LP conversion kit (Modine #53079, if propane is needed)

• Gas supply piping and shutoff valve

Applications

• 2 to 2-1/2 car garages and attached home garages (up to ~1,125 sq ft)

• Hobby workshops, woodworking shops, and maker spaces

• Small to mid-size warehouses and storage buildings

• Greenhouse heating and agricultural outbuildings

• Auto repair bays and service stations

• Retail stockrooms and back-of-house storage

• Maintenance rooms, mechanical spaces, and loading dock offices

• Industrial work areas requiring ETL-certified heating

Why Choose the Modine HD45 Hot Dawg

The HD45 natural gas unit heater is the mid-range entry in the Hot Dawg lineup, delivering 50% more capacity than the HD30 while sharing the same compact 22 x 26.8-inch footprint. Modine's own sizing guide recommends the HD45 for 2 to 2-1/2 car garages, making it the most commonly specified model for standard residential garages and mid-size workshops. The in-shot burner design and permanently-lubricated motor keep operation quiet and maintenance low. 

If the HD30 is too small for your space but you do not need the 60,000 BTU output of the HD60, the HD45 hits the middle ground. 

Buy the Modine HD45 Hot Dawg Gas Unit Heater Online from Cleanflow

Cleanflow stocks the Modine HD45 natural gas unit heater for fast shipping across Canada and the USA. As an authorized Modine supplier, Cleanflow backs every unit with manufacturer warranty support and product expertise. 

Browse all unit heaters or explore the full heater collection to compare options.

Frequently Asked Questions

What size space can the Modine HD45 heat?

The HD45 natural gas heater produces 45,000 BTU input (36,900 BTU output) and handles spaces up to approximately 1,125 square feet with standard 8-foot ceilings and moderate insulation. Modine's sizing guide rates it for 2 to 2-1/2 car garages. For larger or poorly insulated spaces, consider the HD60 or HD75. Use the Cleanflow BTU Calculator to get an estimate specific to your space.

Is the HD45 a good natural gas garage heater for cold climates?

Yes. The HD45 is rated for cold-weather startup down to -40F, making it a reliable natural gas garage heater even in harsh Canadian and northern US winters. The power-vented design keeps combustion gases sealed from the living space, and the 82% thermal efficiency means more of your fuel dollar goes to heat rather than exhaust.

How does the HD45 compare to the HD30?

The HD45 delivers 50% more BTU (45,000 vs 30,000) and moves 43% more air (720 vs 505 CFM) while fitting in the exact same chassis (22 x 26.8 x 12.2 inches). Sound level is 57 dBA vs 53 dBA on the HD30. Both use a 3-inch vent, the same 1/15 HP permanently-lubricated motor, and identical mounting brackets. The HD45 is the right step up when a 30,000 BTU heater falls short for a 2 to 2-1/2 car garage.

Can the HD45 run on propane (LP gas)?

Yes. The HD45 ships configured for natural gas, but it converts to propane using Modine conversion kit #53079, sold separately. The same in-shot burners handle both fuel types, so the conversion is straightforward.

How loud is the Modine HD45?

The HD45 natural gas heater operates at 57 dBA measured at 5 feet. For reference, 57 dBA is roughly the volume of a normal conversation. In independent testing, the Hot Dawg runs quieter than comparable competitor units at the same BTU rating. It is slightly louder than the HD30 (53 dBA) due to higher airflow, but still comfortable for residential garages and workshops.

What ceiling clearance does the HD45 require?

The HD45 mounts just 1 inch from the ceiling on the included angle brackets. On the access side and rear, maintain 18 inches of clearance for service and combustion air. The non-access side needs only 1 inch. Vent connector clearance is 4 inches. In commercial settings, the bottom of the unit must be at least 7 feet above the floor; in residential settings, at least 5 feet.

What is the warranty on the Modine HD45?

Modine covers the heat exchanger for 10 years and all other parts for 2 years. The aluminized steel heat exchanger comes standard; 409 stainless steel is available as an upgrade for environments with higher corrosion risk.

Does the HD45 natural gas heater come with mounting brackets?

Yes. The HD45 includes 1-inch angle mounting brackets that accommodate joists on 16-inch or 24-inch centers. No additional mounting hardware is needed for ceiling installation. (Note: On HD100 and HD125, mounting brackets are an accessory.)

Can I install the gas and electrical connections on either side?

Yes. The HD45 has right or left hand controls. Gas, electrical, and flue connections can be moved to the opposite side by flipping the unit over during installation. This gives you flexibility when routing gas lines and electrical in your space.

Is the HD45 available with a stainless steel heat exchanger?

Yes. The standard HD45 ships with an aluminized steel tubular heat exchanger. A 409 stainless steel heat exchanger is available as an optional upgrade for applications with higher humidity or corrosive air exposure, such as car washes or chemical storage.