Ignition Controls0
Ignition controls in an HVAC system (primarily gas furnaces, boilers, and some packaged units) are electronic modules or circuit boards that manage the safe and reliable ignition sequence for the burners, replacing older constant pilot lights with more efficient methods. They coordinate components like the inducer blower for pre-purge, gas valve opening, igniter activation (via spark from direct spark ignition or glow from hot surface ignitor), flame sensing/proof, and shutdown if flame fails to establish, preventing unsafe gas release while ensuring proper heating operation.
Common types include hot surface ignition (HSI, most prevalent in modern furnaces where a silicon carbide/nitride element glows red-hot to ignite gas), direct spark ignition (DSI, using an electrode to create a spark directly at the burners), intermittent pilot (spark lights a temporary pilot flame first), and older standing pilot systems (now rare due to inefficiency).
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