Straight Tube heaters ideal for complete building heating. Vacuum system pulls products of combustion through combustion chamber for increased radiant efficiency and greater safety. Reliable direct spark ignition and 100% gas shut-off safety control. Up to 50' of ducting in fresh air and 75' sidewall venting capability. Vacuum system features a totally enclosed combustion chamber. Heavy duty draft inducer assembly features permanently lubricated totally enclosed ball bearing motor for maintenance-free operation. Highly efficient aluminum reflectors. Includes diaphragm air switch, heavy duty cast iron burner and burner inspection sight glass. Diagnostic monitoring light system. 120V supply required. The minimum mounting heights are shown for human comfort and uniform energy distribution for complete building applications. Mount heaters as high as possible. Since straight tube are always hotter at the burner end than at the draft inducer end, use U-tubes instead of straight tubes for spot heating applications. CSA certified. Made in the USA.