Hot Dawg Garage Heater Size Picker
Modine makes the Hot Dawg in six sizes, from 30,000 to 125,000 BTU/hr input. Enter your garage to see which one covers its heat loss, with altitude, mounting height and the cost per hour on gas or propane.
Your garage
Hot Dawg size for your garage
HD30: 30,000 BTU/hr input
Your garage needs about 24,500 BTU/hr of heat at 20°F. The HD30 delivers 24,900 BTU/hr, the smallest Hot Dawg that covers it.
Hot Dawg sizes at a glance
The number in the model name is the input in thousands of BTU per hour: the HD45 burns 45,000 BTU/hr and delivers about 37,350 BTU/hr of heat into the garage, or 83%. Size by the output, and compare it with your garage's heat loss, not its floor area.
- HD30: 30,000 BTU/hr input, 24,900 output, 505 CFM, heat throw about 25 ft, mount no higher than 10 ft, about 55 lb shipping weight.
- HD45: 45,000 BTU/hr input, 37,350 output, 720 CFM, heat throw about 27 ft, mount no higher than 10 ft, about 60 lb shipping weight.
- HD60: 60,000 BTU/hr input, 49,800 output, 990 CFM, heat throw about 36 ft, mount no higher than 12 ft, about 80 lb shipping weight.
- HD75: 75,000 BTU/hr input, 62,250 output, 1,160 CFM, heat throw about 38 ft, mount no higher than 14 ft, about 85 lb shipping weight.
- HD100: 100,000 BTU/hr input, 82,000 output, 1,490 CFM, heat throw about 42 ft, mount no higher than 12 ft, about 125 lb shipping weight.
- HD125: 125,000 BTU/hr input, 102,500 output, 1,980 CFM, heat throw about 56 ft, mount no higher than 16 ft, about 125 lb shipping weight.
For our default 3-car garage, 32 × 24 ft with some insulation, the picker lands on the HD45. Figures come from Modine's 2026 sell sheet. Modine's 2023 catalog lists slightly lower outputs for the 45, 60 and 100.
Before you buy one
A Hot Dawg is a vented gas heater: it needs a gas or propane supply line, a 115 V outlet or circuit for the fan and exhauster, and a 3 or 4 inch vent through the wall or roof. Those, not the heater, are most of the installed cost. Our garage heater installation cost page prices each part.
Hang it where the warm air can blow down the long side of the garage, clear of the car's path and of anything stored on shelves, and follow the clearances in Modine's installation manual. Add a carbon monoxide alarm, as with any fuel-burning heater. If there is no gas at the garage, compare it with an electric heater in gas vs electric first.
We have not tested Hot Dawg heaters, and this page has no affiliate links. Sizes are matched to our own heat-loss estimate, never to a maker coverage claim.
Questions people ask
What size Hot Dawg do I need for a 2-car garage?
For a 24 × 24 ft garage with some insulation, kept at 60°F on a 20°F night, our model puts the heat loss at about 24,500 BTU/hr, so the HD30 (24,900 BTU/hr output) covers it. The same garage with bare walls needs about 37,000 BTU/hr, which points to the HD45. Colder towns and higher ceilings push the size up, so enter your own garage above.
Is the HD45 too big for a 2-car garage?
Not always. The HD45 delivers 37,350 BTU/hr. That is more than an insulated 2-car garage needs on a 20°F night, but about right for a bare one or a cold climate. Too big a heater cycles on and off more, while too small a one never catches up, so size from your garage rather than the model number.
How much gas does a Hot Dawg use?
With the burner on, its input rating is what it burns: an HD45 burns 45,000 BTU an hour, about 0.45 therms of natural gas or 0.49 gallons of propane. At 2025 U.S. average prices that is about $0.67 an hour on natural gas or $1.26 on propane. A heater sized for your garage runs only part of each hour once the garage is warm.
What is the difference between the Hot Dawg HD and HDS?
Both burn natural gas or propane and push exhaust out through a small vent pipe. The HD takes its combustion air from the garage. The HDS is separated combustion: it draws all of its combustion air from outside, which Modine recommends where dust, dirt or fumes are in the air, such as a woodshop or a paint area.
Can a Hot Dawg run on propane?
Yes. Modine sells each size for natural gas or propane, and conversion kits between the two. Modine lists the same sizes for both fuels; the fuel cost per hour is higher on propane at average U.S. prices.
Does altitude change the Hot Dawg size?
Above 2,000 ft it does. Modine's catalog says to reduce output 4% for each 1,000 ft above sea level for U.S. ratings (Canada uses the rating plate). At 5,000 ft that is 20% less heat, so set your elevation in the picker.
Sources
Sources last checked November 7, 2026.
- Modine, Hot Dawg Garage Unit Heater sell sheet 6-114.13 (2026) · Input, output, airflow, mounting height, heat throw, dimensions
- Modine, Gas-Fired Power Vented Unit Heaters catalog 6-189.20 (May 2023) · Altitude derating
- Modine, Hot Dawg HD/HDB product page (accessed November 2026)
- Modine, Hot Dawg HDS/HDC product page (accessed November 2026)