The Ultimate Guide to Heating Your Garage with Outdoor Boiler Units

You have several options when considering the best way to heat a garage during the winter. Heating your garage offers numerous advantages, such as creating a comfortable workspace and maintaining a consistent temperature for your vehicle. This blog will guide you if you’re uncertain which method to select. Let’s explore the various options for effectively heating your garage in winter. 

Understand Your Garage’s Heating NeedsBefore selecting a heating system, you must calculate the required BTU output for your garage. In other words, you must figure out how hard your heater must work to warm your garage. Start by asking yourself these questions:

• How cold are winters in your area?
• What is the square footage of your garage?
• Do you already have sufficient insulation?
• How warm do you want your garage to be?

Steps to Heat Your Garage According to Brenda Porter-Rockwell (2025), effectively heating your garage requires careful planning to ensure safety, efficiency, and comfort. This comprehensive guide provides detailed explanations and references for each step to help you achieve the best results. 1. Assess Your Garage’s InsulationProper insulation is essential for adequate heating to ensure your heating system operates efficiently

• Check for leaks: Inspect walls, windows, and doors for drafts. A properly sealed garage helps retain heat and minimizes energy loss. You can use a flashlight or smoke test to identify air leaks. 

• Insulate the walls and ceiling: Using insulation materials such as fiberglass batts, spray foam, or rigid foam boards can significantly reduce heat loss by forming a thermal barrier. For garages, the R-values of insulation should be appropriate for your climate. 
• Seal gaps: Applying weatherstripping to doors and windows helps block drafts. Caulking any cracks around the structure ensures that heat doesn’t escape through small openings. 

2. Select a Heating SystemChoosing the right heating system depends on the size of your garage, its use, and your budget.

• Electric space heaters are portable and budget-friendly, making them suitable for small garages, though they might not be as effective in larger areas. Choosing models with safety features, such as tip-over protection, is essential.

• Propane heaters are powerful and economical, but they need proper ventilation to avoid carbon monoxide accumulation. Always adhere to the safety guidelines provided by the manufacturer. 

• Infrared heaters focus on heating objects and people directly instead of warming the air, which enhances their energy efficiency. They are particularly beneficial for targeted heating. 

• Ductless mini-split systems provide heating and cooling options, making them a flexible long-term choice. While they come with a higher initial investment, they are energy-efficient and easy to manage. 

• Forced-air heaters function similarly to a furnace, rapidly warming larger garages. They are effective but typically require venting to the outside for safety reasons.

3. Install Proper VentilationProper insulation is essential for adequate heating, ensuring that energy is conserved and rooms remain comfortable without overworking the heating system. 

• Ventilation is crucial for safety: Fuel-based heaters like propane or natural gas can emit carbon monoxide. Proper ventilation helps avoid the dangerous accumulation of this gas, which can be fatal. 

• Exhaust fans or vents are key in ensuring fresh air circulation, keeping the environment safe, and preventing humidity problems.

4. Optimize Heat RetentionPreventing heat loss is as important as generating heat.

• Use an insulated garage door: A door that isn’t well insulated can allow cold air to seep in. Insulated doors are designed to stabilize internal temperatures, particularly in winter. 

• Cover windows: Using thermal curtains or applying plastic insulation film to windows can help reduce heat transfer and block drafts. 

• Floor mats or rugs: Concrete floors absorb heat, making the garage feel colder. Adding rugs or rubber mats can help insulate the floor and enhance comfort. 

5. Add a ThermostatA thermostat allows precise temperature control, improving energy efficiency.

• Smart or programmable thermostats are designed for electric or mini-split systems, helping keep temperatures steady while allowing for energy-saving programming when the space is unoccupied. 

6. Consider ZoningIf your garage is connected to your home HVAC system:

• Establishing a separate HVAC zone for the garage allows for independent heating or cooling, enhancing your home’s overall energy efficiency. (Energy.gov, n.d.)

7. Maintain SafetySafety should always be a priority when heating a garage.

• Keep heaters away from flammable items: Make sure to keep heaters at a safe distance from chemicals, fuel, or any other combustible materials that are often found in garages. 

• Install a carbon monoxide detector: This is crucial for garages with fuel-burning heaters, as it helps identify hazardous gas levels. 

• Regular maintenance: It’s essential to clean and inspect your heating equipment regularly to ensure it functions safely and efficiently.

Conclusion

As stated in the article on Oliver Heat Cool, Heating your garage during winter can significantly enhance its functionality and comfort, whether it’s for projects, vehicle storage, or general use. You can create an energy-efficient and safe environment by assessing your insulation, choosing the right heating system, and ensuring proper ventilation. Options like electric space heaters, ductless mini-split systems, and forced-air heaters cater to various needs, while additional steps like sealing gaps, insulating doors, and using a thermostat optimize heat retention and efficiency. With thoughtful planning and attention to safety, your garage can become a warm, practical space all winter long. 

Frequently Asked Questions

1. What is the best way to heat a garage?

Underfloor radiant heating is an excellent option for heating a garage. Electric radiant heating systems use cables installed beneath the floor. These cables generate heat that radiates upward, providing even and consistent warmth throughout the garage at lower temperatures than other heating systems, ensuring no cold spots.

1. How much heat do I need for my garage?

For a 1-car garage measuring between 200 sq ft and 300 sq ft, you would typically need a heater with a 15,000 to 25,000 BTUs capacity. If you have a 2-car garage that ranges from 500 sq ft to 700 sq ft, the recommended heater size would be around 30,000 to 45,000 BTUs. For a 3-car garage, which is about 750 sq ft to 900 sq ft, you should look for a heater with a 45,000 to 55,000 BTUs capacity.

1. Can you leave a garage heater on all the time?

Even if you’re just stepping out for a few quick errands, it’s a good idea to turn off and unplug the unit whenever you leave the garage. Additionally, you should refrain from leaving your garage heater on all night while you sleep. It could overheat, short-circuit, or tip over, which could lead to a fire.

1. What temperature should a heated garage be?

When heating your garage, you don’t have to raise the temperature to match the comfort level of the rest of your home (usually around 65°F to 68°F). Maintaining your garage thermostat at a steady temperature between 40°F and 50°F will help protect the above items.

1. How do you circulate heat in a garage?

For optimal ventilation, the garage should ideally feature two opposite openings. This could include air vents in the garage door and the back wall, a window, or a door. Such a setup promotes air circulation, helps remove humid air, and retains warm air.