CSA 2.17-2017 Gas-fired appliances for use at high altitudes.
The following definitions shall apply in this Standard:
High altitude locations having an elevation above mean sea level between 2000 and 4500 ft (610 and 1370 m).
Low altitude — locations having an elevation not greater than 2000 ft (610 m) above mean sea level.
Appliances for use at high altitucies snail comply with the applicable CSA Standard for tne appliance in addition to this Standard.
Space-heating and water heating appliances intended for installation in mobile housing or recreational vehicles shall be suitable for use over an altitude range of 0 – 4500 ft (0 – 1370 m).
High-altitude ratings may be obtained by a change in orifice size or by a change in manifold pressure when the appliance is equipped with a gas pressure regulator.
Appliances may be equipped or adjusted at the factory for the high altitude rating, or may be field converted to obtain the high-altitude rating using a manifold pressure change, or by using a certified field conversion kit.
4.2 Identification by model number
Where structural changes are incorporated in the appliance by the manufacturer in order to comply with this Standard, the model number designated shall differ from that of the corresponding lowaltitude model. A dual flue or vent collar, a change in orifice size, or a change in manifold pressure, shall not be considered a structural change.
In addition to the marking specified by the applicable CSA Standard for the appliance, the following shall be included on the name/rating plate:
a) for an appliance shipped from the factory equipped with an orifice for a specific altitude: the altitudes as 0 to 2000 ft (0 to 610 m) and/or 2000 to 4500 ft (610 to 1370 m) with the corresponding orifice size, manifold pressure, and ratings;
b) for an appliance using a manifold pressure change to obtain the high altitude ratings: the altitudes as 0 to 2000 ft (0 to 610 m) and 2000 to 4500 ft (610 to 1370 m) [or 0 to 4500 ft (0 to 1370 m)] for multiple-rated appliances with the corresponding orifice size, manifold pressure, and ratings.
In addition, the appliance shall be marked to indicate the altitudes for which it has been adjusted at the factory, and shall include provision to indicate that it has been readjusted in the field to obtain the ratings for the alternate altitude. This Clause may be accomplished by the use of a separate label to be affixed by the installer or by a marking on the name/rating plate, which could be checked off by the installer;
c) for an appliance suitable for installation at 0 to 4500 ft (0 to 1370 m) without change: the altitude as 0 to 4500 ft (0 to 1370 m) with the orifice size, manifold pressure, and ratings.
The ratings required in Clause 4.3.1(a), (b), and (c) of this Clause include input ratings, output ratings, bonnet capacities, and recovery capacities as specified in the applicable CSA Standard for the appliance.
(Refer to Figure 1 for suggested format, based on the aforementioned marking provisions).
CSA 2.17 pdf download.