Here is the scenario.
I have a single bay garage that measures 12×24. The heigh to the bottom of the truss chords is 9′-6″. I would like to heat this space. The front wall is exterior with a 9×7 uninsulated Al door. The side and rear wall are exterior, with a utility door in the side. The remaining wall is adjacent to heated space. The exterior walls have 3.5″ FG faced batts, the overhead door is uninsulated. As of now, there is no insulation or air barrier overhead. I plan to start with 4 mil poly overlapped at the seams overhead. If this is not sufficient, than I might consider 1″ EPS with the seams taped or foamed, but I think this might entail more benefit than cost. The location is SE PA.
My two questions are:
1. How many BTU’s should I look for? The ft³ is about 2736. I don’t need to maintain 70° temps in 0° weather, 50-65° would suit me just fine. I would like enough to warm up the space in an hour, give or take. This will be for auto maintenance, cutting down sheet good to get to the basement shop, etc. Nothing that I can’t wear light gloves and a sweatshirt for. Am I looking at 10,000, 25,000, or >50,000 Btu’s for this application?
2. What type of heat would be the most practical for my needs? I would prefer something portable and unvented. I am not terribly concerned about humidity, just as long as there’s not enough to condense on the poly and rain on me. Should I look at LP, Kerosene, resistance, or…?
Feel free to suggest a specific model if you have one in mind.
This is fairly verbose for a simple question, but I wanted anyone to have the info that is necessary. Thanks in advance.
Jon Blakemore
Replies
In a semi-insulated space, like your garage, 75 btuh/ft^2 is a good place to start, which would work out to about 21,500 btuh.
I would get a simple suspended unit heater, lp if ng is not available, with combustion products vented. Cost about $500.
I've got a 24x24 detached garage with a 9x7 insulated overhead door, no windows, one service door, 8' walls, fg insulated walls and ceiling. Drywall on walls and ceiling. I heat it with a "Modine Hot Dawg", does a nice job. I've got a seperate lp tank for my shop, (house has natural gas-didn't want to go through the trouble to run the gas the 120' out to the shop, plus the seperate tank is easier to break out for tax write-off.)I maintain a temp of 50 degrees when I'm not in the shop and turn it up for when I'm working. I can't remember the BTU's on the unit I have, But I believe they have a smaller unit that would probably suit your needs.