Preface

This publication represents a basic standard for safe operation, substantial and durable construction, and acceptable performance of a gas unit heater, gas packaged heater, gas utility heater, or gas-fired duct furnace. It is the result of years of experience in the manufacture, testing, installation, maintenance, inspection and research on a gas unit heater, gas packaged heater, gas utility heater, or gas-fired duct furnace designed for utilization of gas. There are risks of injury to persons inherent in appliances that, if completely eliminated, would defeat the utility of the appliance. The provisions in this standard are intended to help reduce such risks while retaining the normal operation of the appliance.

Safe and satisfactory operation of gas unit heater, gas packaged heater, gas utility heater, or gas-fired duct furnace depends to a great extent upon its proper installation, use and maintenance. It should be installed, as applicable, in accordance with the National Fuel Gas Code, ANSI Z223.1/NFPA 54; or the Natural Gas and Propane Installation Code, CSA B149.1.

Scope
1.1
This standard applies to newly produced gas fired-duct furnaces, packaged heaters and unit heaters with input rates up to and including 10,000,000 Btu/h (2 931 kW) and utility heaters with inputs up to and including 400,000 Btu/hr (117.2 kW) constructed entirely of new, unused parts and materials:

a) For use with natural gas with inlet gas pressures up to and including 5.0 psi (34.5 kPa); unit heaters, packaged heaters and duct furnace with burners having inputs rates over 400,000 Btu/hr (117 228 kW) may have higher inlet pressures.

b) For use with liquefied petroleum gases; and

c) Convertible for use with natural gas and liquefied petroleum gases, when provision is made for the conversion from one gas to the other.

1.2
The term "appliance" when used herein, applies to gas-fired duct furnaces, packaged heaters, utility heaters and unit heaters. Duct furnaces, unit heaters and package heaters may be factory-built as a single unit or as a package system intended to be disassembled for shipping and reassembled for installation and may be combined with a cooling unit. (See Clause 3).

1.3
Duct furnaces, unit heaters, and packaged heaters may be factory-built as a single unit or as a package system intended to be disassembled for shipping and reassembled for installation, and may be combined with a cooling unit. (See Clause 3).

1.4
The construction of appliances for use with the above-mentioned gases is covered under Clause 4.

1.5
The performance of appliances for use with the above-mentioned gases is covered under Clause 5.

1.6
This standard applies to Category I, Category II, Category III and Category IV Appliances. (See Clause 3).

1.7
This standard covers self-contained, automatically controlled, vented unit heaters, packaged heaters, utility heaters and duct furnaces. These appliances are intended for installation in locations where flammable gases or vapors are not generally present.

Unit heaters, packaged heaters and utility heaters shall have an integral means for circulation of air. Unit heaters, unless for outdoor installation are intended for installation in the space being heated. Unit heaters may be either suspended or floor-mounted and of either the low-or high-static pressure type as defined in Clause 3. Utility heaters may be suspended or floor-mounted and of the low static type as defined in Clause 3. Packaged heaters may be either suspended, floor-mounted, or roof mounted and may be located within or external to the heated space as defined in Clause 3.

These appliances are suitable for use in aircraft hangars, parking structures and repair garages when marked and installed, as applicable, in accordance with:

Standard on Aircraft Hangars, ANSI/NFPA 409;

Standard for Parking Structures, ANSI/NFPA 88A;

Standard for Repair Garages, ANSI/NFPA 88B; and

Installation Code for Natural Gas and Propane Installation Code, CSA B149.1.

1.8
This standard also applies to appliances with draft hoods which are factory equipped with automatic vent damper devices (see Clause 3), hereinafter referred to as vent damper devices.

1.9
A separated combustion system appliance anticipated by this standard is essentially a balanced flue appliance with the air intake and vent outlet in close proximity. Other designs shall be subjected to such additional tests as believed necessary at the discretion of the testing agency.

1.10
Clause 2 contains a list of standards specifically referenced in this standard, and sources from which these referenced standards may be obtained.

1.11
If a value for measurement as given in this standard is followed by an equivalent value in other units, the first stated value is to be regarded as the specification. (See Annex M for Temperature Scales and Conversions).

1.12
Special construction provisions applicable to an appliance designed for use with an optional listed gas conversion kit are outlined under Annex C.

1.13
This standard also applies to newly produced automatic intermittent-pilot ignition systems (see Clause 3), constructed entirely of new, unused parts and materials, to be adapted in the field to a unit heater or duct furnace equipped with an existing continuous pilot burner and which has been examined and tested for compliance with this standard when installed on the appliance. (See Annex D).

1.14
All references to psi (kPa) throughout this Standard are to be considered "gauge" pressures unless otherwise specified.