How to Size a Garage Heater (2024)

FAQs

How to Size a Garage Heater? ›

You can calculate the ideal garage heater for your garage using the formula of size (in cubic feet) times 0.133 times the desired temperature rise. These factors vary, but we generally recommend an 8,000 - 12,000 BTU garage heater for a one car garage.

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.

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.

Too big, and you'll waste money on heating power you can't use. Garage heaters also become physically larger as they increase in size, and a large heater in a small space is cumbersome and difficult to mount.

For example, a 300 square foot room typically requires 7,000 BTUs to maintain a comfortable temperature, while a 1,000 square foot room requires 18,000 BTUs. A simple formula to determine your heating needs is: (desired temperature change) x (cubic feet of space) x . 133 = BTUs needed per hour.

Calculate cooling capacity: You can use a rule of thumb that suggests around 20 BTUs per square foot of space to get an idea of how much cooling capacity you need. Multiply the room's square footage by 20 to get a basic estimate of the required cooling capacity.

The DOE generally recommends 20 BTUs per square foot of living space. That is based on size alone. Therefore, a simple formula for calculating BTUs is to multiply the total square footage of your home by 20. But you may need more BTUs per sq.

5,000–10,000 BTUs: Suitable for small garages or workshops (up to 300 square feet) and ideal for spot heating or maintaining a moderate temperature in a limited space. 10,000–20,000 BTUs: Appropriate for medium-sized garages (300 to 600 square feet) and provides more substantial heating capacity for improved coverage.

For a 150-250 sq. ft garage, 8000 BTU is needed to cool a garage, while a two-car garage requires 10000-12000 BTU.

What is the most efficient heater for a 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.

Gas & Kerosene Heaters

They are a highly efficient garage heating option, which can help you save money on long-term heating costs. These heaters are best for continuous heating, ensuring that your garage is always warm during the cold months.

Sizing a garage heater is a critical part of the process

Buying a unit heater that is too big will cycle on and off frequently, creating drastic temperature swings and increasing wear and tear on your unit heater. Making the wrong selection could end up leaving you uncomfortable and frustrated.

To determine how many BTU you need to cool a 20 x 20 room, multiply the room's length by the width, then calculate 20 BTU for every square foot. Four hundred square feet x 20 = 8,000 BTU.

You'll need 20 BTUs for every square foot of space. It's important to also consider the ceiling height, how large windows are, and if rooms are shaded. Once you calculate the square footage, you'll multiply it by 20. For example, a home with 600 square feet will need 12,000 BTUs.

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.

As a basic rule, the figure will be between 30 and 60 BTUs per square foot.

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.

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.