ANSI Z21.23-2010 (R2020)
Gas appliance thermostats
This publication represents a basic standard for safe operation, substantial and durable construction, and acceptable performance of gas appliance thermostats. It is the result of years of experience in the manufacture, testing, installation, maintenance, inspection and research on gas appliance thermostats designed for the utilization of gas. There are risks of injury to persons inherent in some appliances that, if completely eliminated, would defeat the utility of the appliance. The provisions in this Standard are intended to reduce such risks while retaining the normal function of the appliance.
This Standard applies to newly produced gas appliance thermostats of the integral gas valve type having a maximum operating gas pressure of 1/2 psi (3.5 kPa) or electric type (see Part IV, Definitions), constructed entirely of new, unused parts and materials.
This Standard does not apply to an electric type comfort heating thermostat (wallmounted) for installation remote from an appliance. When the operating performance characteristics of the thermostat can be affected by the separate components, such as power supply, transformer and valve(s), the thermostat shall be tested as part of a complete system. Compliance of a device with this standard does not imply that such device is acceptable for use on gas appliances without supplemental tests with the device applied to the particular appliance design.
An accessory incorporated as an integral part of a thermostat shall comply with all provisions of the applicable standard for such a device.
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.
All references to psi throughout this standard are to be considered gauge pressures unless otherwise specified.