Review on Natural Gas Heater: Mr. Heater Vent-Free 20,000 BTU Blue Flame - Multi-Size Option by Dennis Moonin

I was replacing an existing heater, and so I already had natural gas plumbed to the site. It took me about 1/2 hour to unpack the heater, attach the legs, and install the included AA battery for the pilot igniter. Then I discovered I was out of the yellow Teflon tape needed for gas threads. (Do NOT use the white tape for gas!) I went to the little store down the road and purchased a new roll of the yellow Teflon tape. Using this on the threads I installed the street el which came with the heater, and then installed the 3/8 compression adapter I had removed from the old heater. Then, using the metal flex tube I had removed from the old heater, I connected this heater to the gas, turned the gas back on (there is a shutoff right behind the heater), and lit the pilot. Once it was lit, I turned on the heater with the thermostat on top. The heater immediately ignited. It began to heat immediately. It is silent in operation. The heated air comes out above the glass which is in front of the flame. The flame is even and all blue. It is hard to see when the room is well lit. The heater has been operating for about two weeks now in a space that is about 600 square feet. Night temps have been in the teens. It keeps the space in the 70's. The instructions say this heater may shut off at elevations above 4500'. We live at 4200', and there has not been any issue. We already had an operating CO detector when I installed this heater. If you don't have one, install one before you install the heater.