read teh voltage side to side on each element, you should get around 240V. if this heater is like most, you will ALWAYS have 120v to one side and you can read it thru the element on the other side, so you need to check for the full 240V instead of just adding them up.

The heater is just 120 @ 3 amps - It is natural gas fired and has 2 fans on it, one for combustion air and one for the combustion air. I did put it on a dedicated 20 amp circuit. When it comes to the electrical connections the manufacturer specifications say that it is recommended to be on a separate, grounded circuit with a disconnect means as close to the unit as possible. There was no maximum breaker size listed, unless it is lighting I prefer to use 12 gauge wiring so I put it on a 20 amp breaker. This will be inspected but I just wanted to make sure I didn't make a big mistake with the cord, but as long as that counts as a disconnect means I think I should be OK based upon teh responses here.

Code for horizontal vent runs of a power vented heater (non-condensing) is category 3 venting. Single or double wall are acceptable as long as you follow the vent manufacturer's guidelines. Had to do this recently for a Mr. heater Big Maxx unit. I ended up getting this category 3 vent kit because the Mr. heater one was too expensive.

All useful and helpful so far. Further details, if it matters: Garage is a 900 sqft attached garage, with sheetrocked, uninsulated, 2X6 walls, double-sheetrocked ceiling with no insulation. and insulated doors. Heater has a steel hanging bracket that you bolt to the ceiling joists. Minimum distance from any wall is 6” and bracket provides automatic spacing from ceiling. The breaker box is on a wall about 6‘ from the location of the heater and I was planning for the cable to go about 18” from the back of the heater through an armored jacket until I got to the wall, and then bring the wire up through the wall cavity to the open and accessible attic, and finally back down through the wall cavity to the breaker box. I already have a 30 amp, double pole breaker, and two free slots. I’m in the Pacific NW, so the climate is mild. Would only be using the heater on winter days when the temps outside are in the mid-40’s F down to possibly the mid-20’s. The inside of the garage on the coldest days never gets worse than the high 30’s. I just want to be comfortable doing woodworking.