Calculating BTU for my garage

[aventino68]

About to talk to my steel building manufacturer. Have a 44800 cubic foot area from my calculations, 3200 sq ft with average 14 ft ceilings. Sorting insulation and want to do a double layer of batts type blanket insulation. What does everyone suggest for insulation, haven't read much good on sprayfoam, and what sized heater do I need. When I plug it all into the online calculators it says 180,000 BTU so would that best be split between say 3 smaller 60,000btu heaters? But that all seems really really approximate. I'm up near Toronto.

 

[Showkey]

The wall chart garage heater calculator ( estimate) says 125k but assumes insulation:




Prior discussion on a this topic boils down to the variables used in the calculation.
Variables being insulation, climate, target temperatures, heated all the time or only when used, windows, doors, coming or going doors opening etc
Seat of the pants Guess says 185k is too BIG.

One other seat of the pants guesstimate 40k BTU per 1000 sqft. if the building is insulated.

 

[aventino68]

Thanks for that, I'm still trying to get my head around insulation and condensation issues. I'm thinking I keep it around 50F for when I'm not in it and around 70 when I'm using it. I'm not sure if the idea is to stop condensation on inner walls or allow condensation that then evaporates.

 

[Showkey]

There are dozens of prior posts on metal buildings and condensation........it’s not an easy problem to fix or manage.

 

[aventino68]

Yep, had a look through and hope that the steel building manufacturer's setup works. Going with an air gap between the insulation and the back of the steel siding. I do see problems with the insulated doors though, since I think they can't easily have this.

Will try with 120K btu and see how that works out split between two heaters.