Gas-fired low-pressure steam and hot water boilers
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This is the seventh edition of CSA/ANSI Z21.13 • CSA 4.9, Gas-fired low-pressure steam and hot water boilers. It supersedes the previous editions published in 2017, 2014, 2013, 2010, 2004, and 2000.
The major changes to this edition include the following:
a) updated the reference publications;
b) deleted coverage for manufactured and mixed natural gases;
c) addition of coverage for boilers designed for installation in a recreational vehicle (RV), as well as boilers having a 12 VDC power supply;
d) replacement of the term input rating with maximum input rating or minimum input rating, as appropriate, to clarify requirements applicable to boilers having more than one input rating;
e) elimination of the 5 000 000 BTU/h input rating limit on the use of direct ignition systems for some types of boilers (Clause 4.8.2);
f) removal of the requirement that a manually operated shut-off valve be present downstream of the safety shut-off valves on boilers having a maximum input rating over 400 000 BTU/h (note that a means of testing the safety shut-off valves is still required) (Clause 4.10);
g) added an appliance pressure regulator requirement for recreational vehicles convertible boilers (Clause 4.10.7);
h) added construction and performance requirements for corrugated metal tubing used as gas conduit (Clauses 4.11.11 and 5.31);
i) modified requirements for nonferrous semi-rigid tubing used as gas conduit (Clause 4.11.11);
j) removed references to Type T wire (Clause 4.23.1);
k) revisions to safety circuit wiring requirements (Clause 4.23.10);
l) addition of a requirement for language in both in installation and user’s manuals requiring the boiler installer to verify that at least one carbon monoxide alarm has been properly installed when a boiler is installed inside a residential living space (Clauses 4.33.1 and 4.34);
m) clarification of requirements for flame illustrations in the installation manual (Clause 4.33.1);
n) clarification that a Class IIA-1 labeling system (metal plate secured by mechanical means) is to be used for rating plates that are shipped detached (Clause 4.35.2);
o) added detailed method for input measurement and also excepted boilers with negative pressure regulators from manifold pressure tolerance requirement (Clause 5.3.3 and Annex J);
p) modified requirements for adjustment of minimum test input rate (Clause 5.3.4);
q) clarified when input rate should be verified, and when adjustments should be made, during the course of testing (Clause 5.3.5);
r) added an equation for the calculation of air-free carbon monoxide level and defined ultimate CO2 values to use in these calculations (Clause 22.214.171.124);
s) various changes to burner operating characteristics performance requirements, intended to improve clarity. This includes clarification that tests at 1/3 of maximum input rating only apply to boilers having a manual valve, downstream of the inlet test pressure location, that can be set to a position other than fully open or fully closed (Clause 5.6);
t) clarified that flame roll-out shut-off construction requirement does not apply to boilers having a sealed combustion chamber which inherently prevents rollout. Option of performing the flame rollout shut-off test by disconnecting the motor on an induced draft boiler has also been eliminated (Clauses 4.1.6 and 5.10);
u) eliminated equivalent CO calculations in blocked vent, blocked inlet, and blocked condensate drain tests for boilers having a minimum input rating less than 20% of their maximum input rating. These calculations were unnecessary, given the 1000 PPM air-free limit at minimum input rating for such boilers (Clauses 126.96.36.199, 188.8.131.52.3, and 184.108.40.206);
v) modified wind test performance requirements for boilers other than those supplied with a power burner or operating under forced or induced draft (Clauses 220.127.116.11 and 18.104.22.168);
w) added manufacturing and production test requirements for corrugated metal tubing used as gas conduit (Clause 6.4); and
x) elimination of flue loss calculation coverage and AFUE requirements. Measurement of boiler efficiency is covered by other standards.
This Standard is considered suitable for use for conformity assessment within the stated scope of the Standard.
This Standard was prepared by the Z21/CSA Joint Subcommittee on Standards on Gas-Fired Low- Pressure Steam and Hot Water Boilers under the jurisdiction of the Technical Committee on Gas Appliances and Related Accessories, the Z21/83 Technical Committee on Performance and Installation of Gas-Burning Appliances and Related Accessories, and the Fuels and Appliances Strategic Steering Committee, and had been formally approved by the Technical Committees and the Interprovincial/Territorial Gas Advisory Council.
This Standard has been developed in compliance with Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group.
This Standard has been approved by the American National Standards Institute (ANSI) as an American National Standard.
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,
a) for operation at or below the following pressures and temperatures:
i) steam heating boilers: 15 psi (103.42 kPa) steam pressure;
ii) hot water heating boilers:
1) 160 psi (1.10 MPa) water pressure; and
2) 250 °F (121 °C) water temperature;
iii) hot water supply boilers:
1) 160 psi (1.10 MPa) water pressure; and
2) 250 °F (121 °C) water temperature;
b) for use with
i) natural gas;
ii) propane gas;
iii) LP gas-air mixtures; and
c) for recreational vehicle installation for use with
i) propane gases only; and
ii) 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 and the 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 that 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 certification body.
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.
The values given in US customary units are the units of record for the purposes of this Standard. The values given in parentheses are for information and comparison only.
Note: IEEE/ASTM SI 10 or ISO 80000-1 can be used as a guide when converting imperial units to metric units.
All references to pressure throughout this Standard are considered gauge pressure, unless otherwise specified.
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 separate from the text explanatory 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.
Gas-fired low pressure steam and hot water boilers