Check the manufacturers specs or gas code book. TSSA B149.1 installation of natural gas and propane appliances if you are in Ontario Canada.
No. Gas water heaters are not all designed to use direct venting.
24"
Natural gas space heaters can be bought from numerous stores and retailers online. They are available to purchase from The Home Depot, Lowe's, eBay and Amazon.
wood heaters are hotter
Natural gas is more thin than air, which means it is not as flammable and will more likely go up in the atmosphere. Although it is non-toxic, one should still make way for ventilation avoiding suffocation. Natural gas is clean and efficient. It is surely one of the safer options to bare in mind.
Gas heaters are much more efficient. Electric resistance heaters are, by nature, hideously inefficient.
Propane or natural gas.
Gas water heaters are better than electric water heaters. Although they are not exactly or completely environmentally healthy, they do save you a lot more money and heat up much better.
18 inches above the garage slab
Many people already have gas stoves, and gas water heaters, which burn natural gas. The general public has had access to natural gas for a very long time, at least a century.
the propane company says that it can not be converted to natural gas because of the laws and government regulations
"No, there aren't any Calor gas heaters sold at Lowes. However, there is a Whirlpool 6th Sense 50-Gallon 6-Year Gas Water Heater (Natural Gas) for sale at Lowes."