Heater Sizing for Detached Garage

[Alpinweiss]

Hey guys - I'm setting up my woodworking shop and could use some help getting the right sized heater.

Location/Temp: My shop is in Missoula Montana, it's usually in the teens and twenties deg F but we definitely get weeks in the single digits.

Shop Size/Construction: Shop is a 20x30 detached building, concrete floor, R13 in the walls, and I'm currently putting in ceiling panels (12 foot tall) and planning on blowing in insulation probably at R40/50 above the panels.

Use: I'm planning on keeping the shop at ~50 deg and ramping up to 60 when working in there (4-5 times a week)

I'm settled on Natural Gas and going to get a line run to the shop from the meter. I'm also pretty interested in a separated combustion unit since I'll be making a bunch of sawdust and finishing on occasion. I like the Reznor units... but I honestly have no idea what size. The calculators I've found online are all over the map... I've seen 45k BTU - 110k BTU as results.

I'd love some thoughts/experience! Thanks!

 

[Showkey]

600 sqft shop ( yours is well insulated) this ballpark chart should be accurate enough.
Reality is there are not that many choices 30-45k vs 70-80k vs 100 plus.
Because 80k is twice oversized.




I am at 1000 sqft well insulated with 45k unit in a cold climate.

 

[Alpinweiss]

Awesome - thanks for the help. Was thinking about a 80k BTU unit which sounds like it would have been way overkill. I think I'm going to do a 45k BTU Reznor unit (UDAS-45) and try to set up the CC14 flush mount vent setup. I'll post a pic when it's in place!

 

[zippi]

My garage is 20X25 attached and only the side next to the house is insulated. Nothing in the ceiling or other 3 wall. I installed the Comfort "Zone 5000 watt heater ($89 on sale at Rural King) a couple weeks ago. At 32 degrees F outside I can turn the heater on an within an hour or so it's up to 50 degrees. I set the thermostat there and it does a pretty good job. That's good enough for me with a light jacket to piddle around in the garage on those cold days. Comfort Zone also has a 7500 watt unit as well.