Draft Details

Designation:Z21.13/CSA 4.9
Contact name:Dragica Jeremic
Review start date:Oct 13, 2021
Review end date:Dec 12, 2021
Contact email:kelly.yaremko(at)csagroup.org
Draft Scope/Description:


This Standard applies to newly produced gas-fired low-pressure steam and hot water boilers with gas inlet pressure ratings not exceeding 0.5 psi (3.5 kPa) and having input ratings of less than 12 500 000 Btu/h (3 663 389 W) (see Clause 3), hereinafter referred to as boilers*, constructed entirely of new unused parts and materials, for operation at or below the following pressures and temperatures:

              Steam heating boilers

15 psi (103.42 kPa) steam pressure

Hot water heating boilers

160 psi (1.10 MPa) water pressure

250°F (121 °C) water temperature

       Hot water supply boilers

       160 psi (1.10 MPa) water pressure

       250°F (121 °C) water temperature

a) for use with natural gas;

b) for use with propane gas;

c) for use with LP gas-air mixtures;

d) for recreational vehicle installation for use with propane gases only; and

e) for recreational vehicle installation convertible for use with natural gas and propane gases when provision is made for the simple conversion from one gas to the other.

The construction of boilers is covered under Clause 4 andthe performance of boilers is covered under Clause 5.

*See Clause 7.2 for boilers covered in Canada that exceed the above limits in gas inlet pressure and/or input ratings.


This Standard applies to indoor boilers, of other than the direct vent type which are categorized according to vent pressure and temperature as either Category I, Category II, Category III, or Category IV (see Clause 3), and to outdoor type boilers.


This Standard also applies to direct vent boilers (see Clause 3). A direct vent boiler anticipated by this Standard is essentially a balanced flue appliance with the air intake and vent outlet in proximity. Other designs are subjected to such additional tests as believed necessary at the discretion of the testing agency.


If a value for measurement as given in this Standard is followed by an equivalent value in other units, the first stated value is the specification.


This Standard contains SI (Metric) corresponding to the yard/pound quantities, the purpose being to allow the Standard to be used in SI (Metric) units. (Standard for Use of the International System of Units (SI): The Modern Metric System, IEEE/ASTM SI 10 or ISO 80000-1:2009 Quantities and units – Part 1: General are used as a guide in making metric conversion from yard/pound quantities.) If a value for a measurement and corresponding value in other units are both specified as a quoted marking requirement, the first stated unit, or both are provided.


All references to pressure throughout this Standard are considered gauge pressure, unless otherwise specified.1.8


Clause 7 contains clauses unique to, and required by, Canada.


In this Standard, “shall” is used to express a requirement, i.e., a provision that the user shall satisfy in order to comply with the standard; “should” is used to express a recommendation or that which is advised but not required; and “may” is used to express an option or that which is permissible within the limits of the standard.

Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to provide explanatory text or informative material.

Notes to tables and figures are considered part of the table or figure and may be written as requirements. Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.

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