Garage BTUs to Heat?

[Handyandy23]

I currently have a 45000 BTU Hot Dawg heater in my 20x20 garage, and it does a good job. However, I'm moving to a new house soon with a larger garage of about 22x27 feet. I'm trying to determine if I can just bring my 45k Hot Dawg with me. New house is in Windsor, Canada (just across river from Detroit).

Modine's website suggests to use the 45000 BTU in a "2 to 2.5 car garage", and this garage is technically a 3 car (an 8' door and a 16' door). But it's definitely on the small end of what most would consider 3 cars. I also see the "common" recommendation to be 30 to 60 BTU per square foot. That would only be about 18,000 BTU on the lower end, and 36,000 BTU on the upper end.

Garage and doors are all insulated.

The only other relevant info I can think of is that the ceiling height is about 12.5 feet. I'd think volume is actually a better way to calculate BTUs needed, but most of the "rules of thumb" I'm seeing are based on square footage.

Will I be alright with this heater?

 

[The Cobbler]

my 410 sqft garage with 10' ceilings, r-20 walls and r-40 ceiling heats just fine with a 30k modine. . I think you'll be fine .

 

[Copymutt]

The only caveat I see is if your new digs are a couple thousand feet higher. Derate BTUs for altitude.

 

[finn]

The only caveat I see is if your new digs are a couple thousand feet higher. Derate BTUs for altitude.

Detroit is 656 feet above sea level.

Windsor is across the river.

 

[Stuart in MN]

Rather than guessing, there are any number of heat loss calculators out there online - find a couple of them and plug in the numbers for the garage. They typically require the dimensions, insulation type and thickness, size of windows and doors, your location, and what temperature you plan on keeping it at.

 

[Varty Yo]

You will be fine i have the same unit in my 24x22. I added a ceiling fan to drive the heat down. My garage is old and not insulated well also.

 

[Abeo]

My well insulated 625 sq ft garage is able to be heated with 22000 BTU (barely, but it gets to 20 in the winter eventually). My neighbor has the same size garage but poorly insulated, heated with a 45000 BTU modine unit. It's perfect... Good recovery time, doesn't come on all the time.

 

[ItsNemo]

I've got 50,000 BTU in ~440 square feet in the same climate as you, 2 adjoining walls to house with R22, roof adjoins and is spray foamed R32, R14 one outside wall, R12 door...it takes around a half hour to bring it up to temp and then just maintains fine.

I'd say 45k BTU in that space you'll probably be closer to an hour to bring it up to temp but it will have no problem maintaining temp. If you didn't have a heater already I'd suggest doing a 60k BTU but you should be ok with what you have.

 

[BruceMc]

I keep an 1,100 ft^2 garage at 65º F through prolonged sub-zero stretches with a 40k BTU Toyostove just fine. Decent construction, reasonable level of insulation, and I'm not opening and closing the big doors a dozen times a day.

 

[wanderer]

Youre typically not heating a garage....you're conditioning the space. Typically conditiioning the space requires more BTU's than heating it because it's raising the temp rapidly. Plus insulation really doesn't matter as much. I have 60k BTU's in my 24x36 garage and it's way more than enough either to heat it or just condition the space.