Roberts Gordon GordonRay D can be used for heating nonresidential indoor spaces, such as aircraft hangars and garages. It is a suspended heater that requires consideration of stability, flexibility, safety, and satisfactory operation. The heater must be suspended pitched down (one-half inch in 20 ft) away from the burner. The type of gas appearing on the heater nameplate must be the type of gas used. The heater has a gas inlet pressure of 4.6” W.C. minimum and 14.0” W.C. maximum for natural gas, and 11.0” W.C. minimum and 14.0” W.C. maximum for LP gas. The gas pressure at the manifold is 3.