Tetra installs two kinds of furnaces

Natural Gas Furnace vs Propane Furnace
The natural gas furnace cost and the cost of a propane furnace are comparable in terms of energy efficiency, safety, and environmental footprint. When compared unit for unit, propane is twice as efficient as natural gas. This means you can use half as much propane to do the same job as natural gas. That being said, the cost of a propane furnace is slightly higher than a natural gas furnace. Making the choice between two fuels is a matter of personal preference.

Gas Furnaces
A gas furnace heats your home by burning natural gas or propane. The flames heat up a metal heat exchanger, which transfers its heat to incoming air. The gas furnace’s blower forces the heated air into your home’s ductwork and distributes it throughout your home. As the warm air fills your home, cooler air is drawn back into the gas furnace via return ducts, and the process begins again.