ANSI Z21.11.2-2016 Gas-fired room heaters, volume II, unvented room heaters.
The following definitions shall apply In this Standard:
Air shutter — an adjustable device for varying the size of the primary air inlet(s).
Accessible — that which enables a device, appliance, or equipment to be reached by ready access or by a means that first requires the removal or movement of a panel, door, or similar obstruction (see Accessible, readily).
Accessible, readily — that which enables a device, appliance, or equipment to be directly reached, without requiring the removal or movement of any panel, door or similar obstruction (see Accessible).
Appliances, automatically controlled — appliances equipped with automatic devices that:
a) accomplish complete “turn-on” or “shutoff” of the gas to the main burner(s); or
b) graduate the gas supply to the burner(s) but do not effect complete shutoff of the gas.
Approximately circular opening — any air shutter opening of such shape that its area, when divided by the area of a circle having the same perimeter, is equal to or greater than 0.6.
Automatic gas ignition system — a system designed to ignite and reignite an appliance burner(s). Such systems
a) automatically ignite gas at the main burner, or gas at the pilot burner so the pilot can ignite the main burner;
b) prove the presence of either the ignition source, the main burner flame, or both; and
c) automatically act to shut off the gas supply to the main burner or to the pilot burner and the main burner, when the supervised flame or ignition source is not proved.
Automatic gas ignition system timings
Flame failure re-ignition time — the period of time between loss of the supervised ignition source or the supervised main burner flame and attainment of the capability of the ignition means to ignite gas. During this time period, the main burner gas supply is not shut off.
Flame failure response time — the period of time between loss of the supervised ignition source or the supervised main burner flame and the action to shut off the gas supply.
Ignition activation period — the period of time between energizing the main gas valve and deactivation of the ignition means during a trial for ignition period.
Lockout time — the period of time between energizing the system and lockout if proof of the supervised ignition source or the supervised main burner flame is not established.
Recycle time — the period of time between shutoff of the gas supply following loss of the supervised ignition means or the supervised main burner flame and reactivation of the ignition means.ANSI Z21.11.2 pdf download.