How Many BTUs Do You Need to Heat a Garage? | Always Plumbing & Heating (2024)

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Keeping your garage warm and comfortable isn’t just about installing a garage heater unit. It requires a preliminary check of your garage’s insulation level, overall square feet to be heated, and the optimal spot to set up the heating unit so that the whole garage receives adequate heat.

The size of garage heater is equally important to the quality, efficiency, and durability of the unit. You want to ensure that your unit provides maximum value over a specific period without you having to hunt for a replacement a year down the line.

Here are factors that determine the size and type of garage heater ideal for your space.

Measure the floor space

The total square footage and ceiling height of your garage are key metrics to determine the ideal heating capacity of your heating unit. The physical size of your garage heater does not influence its ability to heat your garage. Rather your unit should have the appropriate power capacity to provide the temperature rise you need.

For a 1 car garage with 200 sq ft to 300 sq ft, the estimated heater size is 15,000 to 25,000 BTUs.

For a 2 car garage with 500 sq ft to 700 sq ft, the estimated heater size is 30,000 to 45,000 BTUs.

For a 3 car garage with 750 sq ft to 900 sq ft, the estimated heater size is 45,000 to 55,000 BTUs.

For a 4 car garage with over 1,000 sq ft, the estimated heater size is over 55,000 BTUs

The height of your ceiling will impact the size of the heating unit you get. A garage that’s less than 8 feet will require a 10%-20% smaller heater than the one that has over 8 feet ceilings. Ensure that you’re calculating your garage space with near-accurate measurements, ideally with the help of a professional HVAC technician as they will evaluate other related factors beyond the garage size.

Ascertain your area’s climate zone

In addition to how large and voluminous your garage is, you want to have an accurate reading of the level of cold in your region. If you’re living in Edmonton, the below chart gives you a close enough overview of what the cold weather months have in store. With average low temperatures hanging between -10 and -14 degrees, your unit should

operate at 20 BTUs to 30 BTUs per square footage. However, these being ballpark estimates, you should confirm accurate cubic feet of cold air in your region and multiply that by the desired warmth in temperature. While these measures are good to get raw estimates, always consult with an HVAC professional to know what the set up and maintenance would look like as the cold levels will determine the output you need from your garage heater.

How Many BTUs Do You Need to Heat a Garage? | Always Plumbing & Heating (1)

Understand your garage type

An attached garage will be easier to heat due to the house’s furnace system exchanging the inflow and outflow of heat. However, a detached garage will require a stronger BTU size unit to heat due to not being attached to your house.

As discussed before, the bigger the detached space, the higher the BTU size to emit the heat output for your ideal temperature.

However, an attached garage isn’t necessarily advantageous over a detached garage. If you do not turn on your garage heater for the entire day, you will run the risk of letting cold air pass via your garage into your home making your HVAC system work harder to sustain indoor heat. Due to this, you end up paying a higher gas bill instead of a detached garage heater.

Check your garage insulation level

Gaps and cracks around the exterior walls and doors of your garage can cause outside air and noise to infiltrate your home. If a garage is not insulated properly, the cold air can freeze up the walls and floors of adjacent rooms to the garage.

According to the City of Edmonton, the average insulation level of home ceilings is a minimum overall RSI value of 6.34 (R36). A significant heat loss prevention is possible with tiny recesses around light fixtures, doors, and plumbing stacks are filled using permanent sealants.

Decide your ideal indoor temperature level

Considering that average indoor temperature is felt between 18 degrees and 20 degrees, the right heating capacity will fall between 20,000 BTUs and 55,000 BTUs. An average Edmonton home’s garage size is between 400 sq ft and 800 sq ft. Depending on the time of year, you will need to amp up your garage heater to deliver the optimum level of indoor comfort you desire.

Advantages of Gas-Powered Garage Heaters

Gas garage heaters use two power sources namely, natural gas and propane gas. Propane-powered heaters are more efficient than natural gas-powered models. However, an energy-efficient model will help save on utility bills provided that your insulation is properly done.

Benefits of Gas Heaters

  • Improved safety as models are run on a spark igniter with no pilot light
  • Stronger heating capacity resulting in faster comfort during colder temperatures
  • Enhanced energy efficiency with heaters vented with a sidewall or roof venting (82%-83% thermal efficient)

The type of garage heater you choose should ultimately come from your expected frequency of use and budget. Contact a certified technician at Always Plumbing and Heating to compare different sizes and models based on your needs.

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How Many BTUs Do You Need to Heat a Garage? | Always Plumbing & Heating (2024)

FAQs

How Many BTUs Do You Need to Heat a Garage? | Always Plumbing & Heating? ›

For a 1 car garage with 200 sq ft to 300 sq ft, the estimated heater size is 15,000 to 25,000 BTUs. For a 2 car garage with 500 sq ft to 700 sq ft, the estimated heater size is 30,000 to 45,000 BTUs. For a 3 car garage with 750 sq ft to 900 sq ft, the estimated heater size is 45,000 to 55,000 BTUs.

How many BTUs do I need to heat my garage? ›

What is the right size garage heater for a two car garage? To heat an average two car garage, you'll need a garage heater that is capable of heating roughly 6,000 - 9,000 cubic feet of air. We recommend getting a 30,000 - 50,000 BTU garage heater to get your two car garage to a comfortable temperature.

How big of a heater do I need for a 1200 square foot garage? ›

The general guideline when sizing heaters is 10 watts for every square foot of space. For example, the NewAir G56 Electric Garage Heater has a wattage of 5600 watts, which means it can easily and effectively heat an area of up to 560 square feet.

How much BTU do I need for heating? ›

Generally, your temperature control system should have 20 BTU for every square foot of living space in the area you wish to heat or cool. For example, if your room or area is 400 square feet in size, then you should opt for a temperature control system with a capability of around 8,000 BTU.

How many square feet will a 5000 BTU heater heat? ›

While determining the right BTU rating can be a challenge, the U.S. Environmental Protection Agency suggests using 20 BTU per square foot, which equates to 5,000 BTU for a 250 square foot room.

How do you calculate heat load for a garage? ›

Roughly the formula comes out to this: (Insulation * Cubic Feet of Garage * Temperature Rise) / 1.6 = # of BTU. In an area of 3,840 cubic feet, with a 35 degree temperature rise with average insulation (or 1) would come out to this: (1 * 3840 * 35) / 1.6 = 84,000 BTU.

Can a heater be too big for a garage? ›

A garage heater that is too large for the space will not heat the space more quickly. A heater that is too large for the room will continue to heat for an extended period of time beyond the temperature set point, wasting energy. We call this a temperature swing.

What is the best way to heat a 1000 square foot garage? ›

In-Surface Radiant Heat

Unlike other heating methods, it heats a surface, rather than the air around it. In-surface radiant heat is one of the most efficient ways to heat a garage. Pros: Versatile option that can be installed in your garage floors, walls, or ceiling.

What is the best size garage heater? ›

Garage Square Footage

Furnace capacity is often measured in British Thermal Units (BTUs), and the rule of thumb is to provide 25 to 30 BTUs per square foot. For example, if your garage is 400 square feet, you'll need a furnace with a capacity of 10,000 to 12,000 BTUs.

How much will 1 BTU raise the temperature? ›

One Btu is the quantity of heat required to raise the temperature of one pound of liquid water by 1° Fahrenheit (F) at the temperature that water has its greatest density (approximately 39° F).

Is 50000 BTU hot enough? ›

A fire pit generating up to 50,000 BTU will be very warm if you sit close to the table and can heat up an area between 675 sq ft and 700 sq ft. The distance from the 50,000 BTU fire pit at which you will feel comfortably warm on a cold evening outdoors is between 8 and 10 feet.

How many BTU do I need to heat a 20x20 room? ›

HVAC contractors use a rule of thumb to allocate 20 BTUS to every square foot of space inside your home. For example, if your room is around 2,000 square feet, you'd require a system with a BTU rating of 4.3 out of 5.

How many BTUs to heat a garage? ›

If the temperature outside is 30°F and you'd like it to be 70°F in your garage, the desired temperature change is 40°F. Those two numbers multiplied by . 133 reveals you'll need a little more than 42,500 BTUs per hour to keep your workspace at 70 degrees.

How big of an area will a 60000 BTU heater heat? ›

Furnace and Air Conditioner size for a Semi-Detached 2-storey House
Semi-detached House square footage *Furnace Output [BTU/hr]
1500 to 1800 sq ft50,000 BTU/hr
1800 to 2200 sq ft55,000 BTU/hr
2200 to 3000 sq ft60,000 BTU/hr
*The above square footages do not include the area of the basem*nt.
2 more rows

Is 8000 BTU enough for a bedroom? ›

If your space is 300 square feet, you want to find a model capable of producing at least 6,000 BTUs. As a guide, consider 5,000-BTU models for rooms 150 square feet or smaller, 8,000 BTUs for medium-size rooms (340 square feet), and 12,000 to 14,000-BTU models for rooms with square footage from 550 to 800.

Will a 30000 BTU heater heat a garage? ›

For a 2 car garage with 500 sq ft to 700 sq ft, the estimated heater size is 30,000 to 45,000 BTUs. For a 3 car garage with 750 sq ft to 900 sq ft, the estimated heater size is 45,000 to 55,000 BTUs. The height of your ceiling will impact the size of the heating unit you get.

Is 8000 BTU enough for a garage? ›

For a 150-250 sq. ft garage, 8000 BTU is needed to cool a garage, while a two-car garage requires 10000-12000 BTU. You can also use a BTU calculator to calculate the size requirements easily. You will need to make slight changes depending on your location.

How many BTUs does it take to heat a 20x20 room? ›

APPROXIMATE BTU OUTPUT NEEDED BY SQUARE FOOTAGE
APPROX. SQ.FT.RECOMMENDED INSULATION
Up to 2006,000 BTU
Up to 40012,000 BTU
Up to 60018,000 BTU
Up to 80024,000 BTU
17 more rows

How many feet will 30000 BTU heat? ›

The calculation is simple. A basic rule of thumb for furnace size calculation is that it takes 30 BTUs for every square foot of house. So, if you have a 1,000 square foot house, you need a furnace that has a 30,000 BTU output.

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