• A.S.M.E. (American Society of Mechanical Engineers)
Section I, IV, VIII, "S", "U" & "H" stamps.

• T.S.S.A. (Technical Standards & Safety Authority) www.tssa.org

• C.S.A. (Canadian Standards Association)

• C.G.A. (Canadian Gas Association) Includes

• UL (Underwriters Labratories)

• National Board

• C.S.A. Combustion Efficiency Measurment