Any HVAC people in here? Looking for advice.

Looking to get a heater for the garage and after doing some research I see many options and don't know what to do. Note that I am leaning towards something I turn on when I plan to work in the garage, not something I will leave on all winter. I currently have a torpedo heater that heats things up fast but wouldn't mind getting rid of the smell, having to buy kerosene, and free up some floor space.

The house is new and it's a 3 car attached garage. A third of the walls are shared with the house. Walls and ceiling in the garage are fully insulated. 22' x 32' x 10' ceilings.

Originally was looking into a 30,000 BTU natural gas wall mounted ventless heater. Might be a good option but don't know much about them, a friend recommended it. Will this be enough to warm the garage within an hour or two? I understand ventless heaters put moisture into the air and can cause issues. Would this be an issue in a garage where it's not tightly sealed and would only be run intermittently as opposed to all the time?

Other options are...

A direct vent heater but of course cost more up front and cost more to install.

240V electric. Maybe I could run off of my 240V 30A receptacle I have for my welder?

Sure there are other options I haven't thought about.

Any help and advice is appreciated.

reznor v3
You want to vent the products of combustion. Once installed you may find yourself in the garage more.

I have a 700 sqft garage with a 18,000 Btu natural gas wall heater. After about 10 minutes on high you have to back it off to the lowest setting or you will be too hot. In the garage you will have no problem with moisture, CO or fumes.

I've even used it with the door open awhile watching football at nigh with friends just to take the chill off. With natural gas so cheap these days the bill was pretty cheap. Back when gas was high when I first bought the heater and ran it in 2005 fall/winter it jacked my heating bills up like $200 for a couple of months for weekend use only.

Think I've decided to go with an electric heater.

http://www.homedepot.com/p/King-Ele...er-with-Built-In-Thermostat-KBP2406/205381668

No moisture issues, can install myself, still over 19,000 BTU's. Great reviews on Amazon with many saying they heat areas larger than mine just fine with it.

I'm reading to much about the moisture issues associated with the ventless natural gas heaters. Also sounds like since it's using the air in the room it's heating, it might not be the best in a garage with fumes, gas, chemicals, etc.

Direct vent systems just cost a lot more for the system and install, just more than I'm looking at getting into right now.

I would not go ventless. They stink, literally. Electric heat is expensive. You have natural gas supply go with that. Use a small forced air high efficiency furnace so you can direct vent through the wall and bring fresh outside air in for combustion air. You can add on air conditioning if you choose. I heard Comfortmaker is coming out with a small furnace. I think it's 40,000 btu. Are you installing the equipment or having a contractor do it?

If I go with something using the natural gas, I would have a pro do it. If I go electric like I am thinking, I will install it myself.

I am thinking with the electric it wouldn't take much to keep the garage at 40 degrees, don't think it's much colder than that anyways. Then once in a while I turn it up to 60 when I want to work out there. If I use it like that I don't think it would be very expensive.

Does you house have forced warm air or do you have a boiler. Do you have a gas hot water heater.

Forced air heat, natural gas. Electric water heater.

Get rid of the electric hot water tank. Replace it with gas and you may even qualify for a rebate. Off the Nat Gas hot water tank run a space heating loop if you local code allows.
Could be base board or a fan coil. There's cost savings in getting rid of electric HW.