So I have a two car cinder block garage that measures 31’x25’ (775 square feet). Inside of that, I have one of the car slots turned into a home gym, a room that’s 11.5 x 14.5 (167 square feet), with uninsulated plywood walls. So the main section is 608 square feet. The gym I heat as needed.
My question is heating the main section when I am working on something there (and i’m not looking to cook the place. 60ish is a good temp for working). I have a wood burner that heats it nice, but takes a while to heat it up. The wood burner is good if I am spending hours out there. If I am spending less than an hour (or even an hour and a half) in the garage, there is no point in firing the wood burner up.
So I was thinking about installing an electric forced air ceiling mounted unit. I was looking at a 5000 watt unit, that is rated for the size, but I was thinking that a 7500 or 10000 watt unit would heat it up much faster. Then I can just turn the unit down to maintain the temp.
But I can wire the 5000 watt unit to an existing unused 30amp breaker (10 gauge wire is there too), so that would be easier.
So really, I am wondering if it would be worth the extra cost work of going with a 7500 or 10000 watt unit over the 5000 watt.
In my two car garage, with a concrete floor, no insulation (just plywood and siding on the outside) on the three sides not attached to the house as well as no insulation on the roof, my 5000W heater doesn’t do a whole lot.
I haven’t had a lot of opportunities to try it out, but I suspect, like a similar propane one I have, if it was 30ish degrees out, it could probably get warm enough to be comfortable out there if I let it run for an hour or two.
But the few times I’ve tried it, it’s been hovering around 0 degrees. When it’s that cold, it hardly even makes a dent.
Having said that, you’re only heating about a quarter of that space. I’d think even with just plywood, as long as there’s a ceiling on your room, it would heat that area just fine and not take very long to do it.
I’m guessing one or two of those walls is an exterior wall of the garage as well. If you could throw some insulation in there and put some drywall/plywood over it, that would help tremendously. If you even made the room a hair smaller so there’s an airgap between the exterior wall and your room, it would make a big difference.
Similarly, getting a few rolls of insulation or even some styrofoam and just laying it on top would help keep the heat in.
The one you linked to, just so you know, is 240. Make sure you have access to 240, on a 30 amp breaker, in your garage.
I have about a 800 sq ft cinder block garage and use a kerosene heater when I need to work on one of the cars in the winter or do other garage work. It is 23000 BTU’s which converts to about 7000 W. It does warm it, but it’s not instant warmth either but not too long either - Sorry don’t have warm up times. Also I usually crack the main door for ventilation.
With your smaller space due to your home gym taking room up not in this heating equation and not needing to crack the door for electric, and most importantly ability to heat the air and have that blow directly at you and your work space I’d say you can get along nicely with 5000 W fan forced. Though you might look into radiant heaters too. They can provide some instant heat on you and where you are, and for longer times there could be used till the wood stove got going or just lower the setting on them.
Also not that cinderblock is not good insulation and I am looking at ways to increase the insulation value of the walls.
Not to fight the hypothetical, but… okay. If the wood burner heats the place nicely if it’s given time to do so, could you just plan your several hours a week in advance so that you can go out there ahead of time and light the wood burner, or is it more spur-of-the-moment shop time?