Find the Best Garage Heater for Your Needs

Everyone uses their garage for something different. Whether you are storing your 1966 Chevy, using the space to work on projects, or simply using it for storage, you probably want the space climate-controlled. Most central heat systems do not extend into the garage or work space, but this space is part of your home, so why wouldn’t you want it heated like any other part? If this is a thought you have had, it might be time for a garage heater. 

In essence, installing a garage heater is like adding another room to your home. No longer is the garage a freezing, unusable space for months out of the year. Imagine opening the door to your garage on a -5° day and being greeted with a 60° space. No more waking up early to start your car. Just step into your garage and enjoy the warmth! 

Garages are different from other spaces in your home. Most garages are not built to the same insulation standards as the rest of a home. The door or doors also present a challenge as opening a 8 ft x 7 ft door even for a minute can allow a lot of the heat in the space to escape. Even if your central heating system has a vent in your garage, it will take a long time to get the space back up to normal temperature. 

In this guide, you will learn about the different types of heaters that are commonly used in garage and workshop spaces. No matter what your budget is or how big your space is, we have the right heater for you! 

Sizing & Determining BTUs

Gas heating units for garages and workshops are available in a variety of sizes, from as compact as 6,000 BTU all the way up to 400,000 BTU. Smaller heaters may be used in both residential and commercial applications, while larger heaters (typically over 125,000 BTU) are suited for commercial use only. 

To determine which size heater you need, a few different factors need to be considered. The most important of these factors is the size of the space you wish to heat — a 10,000-square-foot space is going to require a much higher BTU rating than a 600-square-foot space, for example, and too low a BTU rating is not going to heat the space properly, while too high a BTU rating is going to waste energy. Also important is the level of insulation present in your garage space, as well as the coldest average temperature your region experiences. 

The easiest and most accurate way to figure out what size heater you need for spaces up to 1,000 square feet is to gather the information outlined above, and plug it into our Heating BTU Calculator. For spaces between 1,000 and 5,000 square feet, you can contact us for assistance with sizing. For any space larger than 5,000 square feet, it is generally best to contact a local HVAC professional for assistance with sizing. 

Types of Heaters

There are many types of heaters that can be used for your garage or workshop. Each heater has its advantages and disadvantages, so this guide is designed to help you figure out the type that is right for you. 

Vent-Free Heaters

Vent-free heaters offer the most simple and straightforward solution for heating your residential garage space. 

Vent-free systems are 99.9% fuel efficient. This is because, with no required venting, the energy and warmth remains in the room instead of being lost to the outside. These heaters will also continue to work in the event of a power outage, with only the blower (if the unit has one) ceasing to function. 

While vent-free heaters do add moisture and remove oxygen from a room, all units have an Oxygen Depletion Sensor (ODS), which will shut off the heater before oxygen levels reach an unsafe level. Periodic opening of a door or window will take care of the additional moisture level as well. 

Vent-free heaters can only go up to 30,000 BTUs, so keep in mind that they are only suited for use in spaces up to 1,000 square feet in size. Offered in both natural gas and liquid propane, the two most common types of vent-free heaters are infrared and blue flame

Infrared/Radiant Heat 

Infrared heaters provide direct radiant heat. Instead of heating the air in the room, infrared heaters focus heating energy on objects and people. While you may not feel the heating effects throughout the space as quickly as you would with a unit that heats the air around you, infrared heat is more comfortable, more even, and will keep you and the room’s surfaces feeling warm even after the unit is turned off. For best results, set up the infrared heater within close proximity to your workspace. 

Blue Flame 

A blue-flame heater will heat the air in the room. It starts with heating the wall of the side of the room where it is installed. Heat will then move up towards the ceiling, and eventually spread throughout the entire room. A ceiling fan with the blades reversed is a great asset with a blue-flame heater as it will help circulate the warm air throughout the room to make the heater more efficient. Many are also available with blowers to circulate the heat.

Is a vent-free heater right for me? 

Vent-free heaters are a quick, easy, and cheap solution for garages. If you have an older garage that is uninsulated or is otherwise not perfectly sealed, a vent-free heater could be a great choice for you. 

Keep in mind that thermostats are only available on some vent-free heaters. The units that do have thermostats available are not the most accurate. They are unit mounted and only give you choices like high, medium, and low. If you are looking to maintain a specific temperature, a vent free heater might not be the best choice.

Installation Difficulty: Easy 

Since no venting is required and the use of electricity is mostly optional, a gas connection is all that is needed to install a vent free heater. These heaters are available for use with propane, natural gas, or in some cases the heater will support both. Simply run a gas line to the heater, install a shutoff valve, and use a flexible gas pipe to connect the heater. All heaters include a wall mounting bracket. Floor stands are included with some heaters and are available optionally for others. 

*Note for liquid propane users: Models using propane gas must be operated with a 100 lb or larger tank and an external regulator with an output of 11 - 14” WC. 

Price: $200-$950

Vent free heaters are the most affordable option for heating your garage or workshop. 

Check out our top three ventless heaters: 

See our full selection of ventless garage heaters here.

Power Vented Unit Heaters

Power vented unit heaters are the most popular type of garage heaters. They’re used in all kinds of large open spaces, from garages, to warehouses, to barns, and more. 

Unlike traditional gravity vented heaters, power venting helps to eliminate heat loss up the flue pipe. The slightly higher up-front cost is easily returned over the life of the heater thanks to its ease of use, efficiency, and longevity. These heaters range in capacity from 30,000 to 400,000 BTUs and can be vented either horizontally or vertically. They are ceiling-mounted so that they stay out of your way instead of taking up valuable floor or wall space. Paired with a standard 24-volt thermostat, these heaters can keep your space at any temperature from 35 degrees all the way up to 90. All Reznor unit heaters are factory-set for natural gas but can easily be converted with the use of a kit for liquid propane use. Unit heaters are available in two main configurations: standard and separated combustion. 


Reznor’s popular UDX series of heaters is the best choice for most spaces. With their sleek, compact design, they stay out of the way, leaving plenty of headroom for cars, storage, and more. The heater’s 83% efficiency allows it to save you money while keeping you warm. Check with your local utility provider to see if the heater qualifies for a rebate or incentive. Adjustable louvers allow you to control where your heat is going, while an electronic ignition system allows for easy starting every time. Simply set your thermostat and let the heater do the rest. 

Installation Difficulty: Moderate

Units are mounted from the ceiling using either an installation kit or threaded rod. The Quick Sling installation kit takes the hassle out of installation. It allows for easy mounting of the heater approximately 6” down from the ceiling. All hardware is included to make mounting a breeze. 

Standard unit heaters can be vented horizontally with Category III stainless steel venting. The vent pipe must be routed through a side wall and terminated with a vent cap. Unit can also be vented vertically with type B venting. A single vent pipe must exit the unit and then be routed up and through the roof. A vent kit can be used for basic installations, but depending on your needs more or less vent pipe may be required. 

Capacity of Piping  Cubic Feet per Hour based on 0.3” w.c. Pressure Drop  Specific Gravity for Natural Gas -- 0.6 (Natural Gas -- 1000 BTU/Cubic Ft)  Specific Gravity for Propane Gas -- 1.6 (Propane Gas -- 2550 BTU/Cubic Ft
Length of Pipe Diameter of Pipe
½” ¾” 1” 1-¼” 1-½” 2”
Natural Propane Natural Propane Natural Propane Natural Propane Natural Propane Natural Propane
20’ 92 56 190 116 350 214 730 445 1100 671 2100 1281
30’ 73 45 152 93 285 174 590 360 890 543 1650 1007
40’ 63 38 130 79 245 149 500 305 760 464 1450 885
50’ 56 34 115 70 215 131 440 268 670 409 1270 775
60’ 50 31 105 64 195 119 400 244 610 372 1105 674
70’ 46 28 96 59 180 110 370 226 560 342 1050 641
80’ 43 26 90 55 170 104 350 214 530 323 990 604
90’ 40 24 84 51 160 98 320 195 490 299 930 567
100’ 38 23 79 48 150 92 305 186 460 281 870 531
125’ 34 21 72 44 130 79 275 168 410 250 780 476
150’ 31 19 64 39 120 73 250 153 380 232 710 433
175’ 28 17 59 36 110 67 225 137 350 214 650 397
200’ 26 16 55 34 100 61 210 128 320 195 610 372

Note: When sizing supply lines, consider possibilities of future expansion and increased requirements. Refer to National Fuel Gas Code for additional information on line sizing. 

Some other things to keep in mind about standard power vented unit heaters: 

• A gas pipe must also be run to the unit. For heaters up to 200,000 BTUs, a ½” gas connection is required. Larger heaters will require a ¾” connection. Depending on the length of your gas pipe run and the BTUs of your heater, a larger feed pipe may be required. Always make sure to install a shutoff valve between your feed pipe and the flexible line used to attach the heater.

 • All Reznor Unit Heaters come pre-set for natural gas. If you are using a heater for propane, a liquid propane conversion kit is required. This kit consists of a new gas orifice that must be installed inside the side access panel of the heater as well as a replacement spring that goes into the gas valve. This process must be completed by a trained gas technician and all instructions must be followed. Exact conversion producers vary for each model.

• For installations at altitudes up to 6,000 feet above sea level, adjustments can be made to the gas valve to optimize performance. For installations above 6,000 feet, a high altitude kit is required. 

• A 115 volt power source is required to operate the fan and spark ignition. A dedicated line voltage supply with disconnect switch should be run directly from the main electrical panel to the heater. All external wiring must be within approved conduit and have a minimum temperature rise rating of 60°C (140°F). Conduit must be run so as not to interfere with the heater access panel. 

Finally, a wall mounted thermostat must be used to control the unit. Standard 18-gauge thermostat wire must be run from the panel on the back of the heater to your thermostat. Any 24-volt thermostat that supports single stage heating can be used such as the ICM FS1500L.

Price: $1000-$3000

Prices vary depending on a variety of factors including the size of the unit needed, fuel type (liquid propane conversion kits are $90), and other accessories required. 

Check out our top three hanging gas heaters:

See our full selection of Hanging Garage Heaters.

Separated Combustion 

Separated combustion unit heaters pull in combustion air from outside and then vent exhaust back out without using any of the air in your space. This kind of unit is ideal for a space that is completely sealed, like a modern garage with spray foam. It also works well for spaces where there are particles, dust, or other combustibles in the air. If you do a lot of woodworking or painting, this is the unit for you. 

Installation Difficulty: Moderate 

Separated combustion heaters install very similarly to standard unit heaters, but they require two vent pipes instead of one. The two pipes then join at the required vent box where you use a single concentric vent that exits the building. 

Price: $1400-$4000 

Separated combustion units are more expensive than standard units and should only be used where required. 

Shop for Reznor UDZ Separated Combustion Unit Heaters.

Wall Mounted Direct Vent Heaters

Direct vent furnaces and heaters are ideal for garages and workshops thanks to their wall-mounted, space-saving design. Vented heaters are also ideal for spaces that do not have windows, as carbon dioxide, moisture, and other by-products of combustion are safely vented outside through the wall. 

With pricing often falling between vent free heaters and unit heaters, direct vent heaters offer an economical alternative for heating, especially where separated combustion is required. Direct vent heaters use a two-pipe system to pull in outside air for combustion and safely exhaust fumes back outside. All direct vent heaters include a thermostat, giving you full control of your heater. There are three types of direct vent heaters: direct vent gravity, power direct vent, and direct vent counterflow. 

Direct Vent Gravity 

Available from 10,000 to 35,000 BTUs, direct vent gravity heaters are adequate for small to medium size garages and workspaces. Electricity is not required for operation; however, an optional blower can be installed to better circulate the air in your space. 

Power Direct Vent

These heaters require power but deliver much higher fuel efficiency up to 92%. Models from Rinnai will even modulate the heat output to match the needs of the space and make for more even heating.

Direct Vent Counterflow 

Available from 40,000 to 60,000 BTUs, direct vent counterflow heaters are suitable for large spaces in the 1,000-2,000 square-foot range. These heaters are taller and use an integrated blower fan to push air across the combustion chamber. Electricity is required for operation. These heaters offer 77-80% efficiency in a compact design. 

Installation Difficulty: Moderate 

Direct vent furnaces include all required venting materials. These heaters are vented out the wall directly behind the heater. Depending on the wall’s material, installation can be difficult.

• A single hole will need to be made for the two concentric pipes to exit. 
• A gas line will need to be provided. 
• Power might be needed depending on the heater you select. 
• Thermostats are included or can be purchased with the heat and can be wall mounted or mounted on the unit itself. 

Price: $700-$3800 

Prices vary based on the number of BTUs you need and the efficiency of the heater. 

Top Direct Vent Heaters: 

See our full line of Direct Vent Gas Heaters.

Electric Heaters

Electric heaters are often a last resort for heating. There are only limited sizes available for residential use and they are very expensive to operate. If electric is your only option, Ouellet and King make high-quality commercial grade heaters that can be used. These heaters are engineered to get as much performance as possible out of an electric heater. Available from 6,000 to 34,000 BTUs, these heaters will work in small to midsize spaces. 

Installation Difficulty: Easy 

Electric unit heaters are compact and easy to mount. A ceiling and wall mounting bracket is included. All you have to do is supply power to the unit. Heaters require a 240-volt line with anywhere from a 15-amp to a 50-amp breaker, depending on the heater. 

Price: $600 - $2200

Prices vary based on the number of BTUs you need and voltage. Be sure to select the correct size for your space. 

View our full selection of electric unit heaters.

Energy Costs 

It is difficult to calculate energy costs for a gas appliance. The outside temperature, size of your space, insulation, number of people, equipment in the space, temperature you set, and more can all affect how often your heater will run and therefore how much fuel it will use. There are some calculations that can be done to help figure out how much a heater will cost to use. 

Calculating natural gas usage 

Calculate operating cost per hour of full operation bellow

One cubic foot of natural gas contains about 1,032 BTUs. This means that a 30,000 BTU heater will use about 29 cubic feet of natural gas per hour (30,000 ÷ 1,032 = 29.07). This calculation assumes that the heater is running at full blast for an hour, which most heaters will not do. 

Based on your thermostat setting, the heater will cycle on and off throughout the day. According to the US Energy Information Administration, the average price per thousand cubic feet of natural gas is $10.06. This means that the 30,000 BTU heater would cost about $0.29 per hour of full power operation ($10.06 ÷ 1000 = $0.01006, $0.01006 x 29.07 = $0.292). This is where thermal efficiency plays a big role in cost. You will see many of the heaters list a percentage for how efficient they are. This percentage can be used to calculate how much of the gas is turned into usable heat. 

The Reznor UDAP-30 30,000 BTU hanging garage heater is rated at 82% efficiency, meaning for every hour it operates, it will use 30,000 BTU of natural gas and will put 24,600 BTU of heat into the space (30,000 x .82 = 24,600). If we take the Williams 30,000 BTU Direct Vent Heater, which is rated 73% efficient, it will use the same 30,000 BTU of natural gas but will only result in 21,900 BTU of usable heat being put into the room (30,000 x .73 = 21,900).

Calculating propane usage 

Calculate operating cost per hour of full operation bellow

The same ideas can be used for calculating propane usage. One gallon of propane contains about 91,333 BTUs. Using the same 30,000 BTU example, it would require 0.328 gallons of propane per hour of full power operation (30,000 ÷ 91,333 = 0.328). According to the US Energy Information Administration, the average cost of one gallon of propane in 2016 is $2.022 per gallon. Therefore, the 30,000 BTU heater would cost about $0.66 per hour of full power operation (0.328 x $2.022 = $0.663). 

Calculating electric usage 

Calculate operating cost per hour of full operation bellow

Electric heating is calculated differently. Most electric heaters are sold based on the number of kilowatts they are rather than their BTUs. Each kilowatt is equal to 3,412 BTUs. The Ouellet Cyclone Commercial 9.9 kW Electric Unit Heater, which is about 33,780 BTUs, requires 9.9 kilowatts per hour to run. According to the US Energy Information Administration, the average cost of one kilowatt hour in July of 2016 was $0.1268. This means that the heater would cost about $1.25 for every hour of full power operation (9.9 x $0.1268 = $1.255). Please keep in mind that these are estimates and your actual costs will vary. 


All of our gas heaters come with a parts-only warranty. This means that if anything goes wrong with the heater, a part will be provided to you at no charge, but the labor to replace that part is not covered. If you are handy, this might not be a problem for you, but why worry when you can purchase a labor warranty with your heater? 

Total Home Supply offers the exclusive option to purchase a 5-year service plan that fully covers not just the parts, but also the labor on your heater. If you purchase this plan, all you have to do when you have a problem is call and a service tech will come take care of everything for you. Be sure to select the extended service plan options when purchasing your product to ensure that you are covered. 

We hope this guide has made the garage heater buying process easier, but if you still have questions please do not hesitate to reach out to us! Our trained sales representatives are here to help you through the entire process, from sizing your rooms all the way through installation questions. We know you will love your new garage heater!