ULC 635

1 SCOPE
1.1 This Standard covers lining systems for existing masonry chimneys, which may or may not incorporate a liner of fire-clay tile, and existing factory built chimneys and vents.

1.2 Lining systems shall be classed as follows:
Class 1 – For the venting of gas-fired appliances where the temperature of the flue-gas products is 135 °C or above, but does not exceed 245 °C;
Class 2 – For the venting of oil and gas-fired appliances where the temperature of the flue-gas products does not normally exceed 300 °C; and
Class 3 – For the venting of oil-, gas- and solid-fuel fired appliances where the temperature of the flue-gas products does not normally exceed 650 °C.

1.3 Lining systems as covered by these requirements, are not intended for use with Type BH Gas Vents, or with appliances that create positive pressures within the lining system, or cause condensation of corrosive acids, unless specifically listed for such applications.