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PART 7 COMPONENTS
7.1 HOT SURFACE IGNITOR
The silicon carbide igniter is inserted directly through the fan flange and held in place by two screws. A hold down bracket as well as
sealing gasket above and below the igniter assures a good seal. Care must be taken when removing and/or installing the igniter since
the silicon carbide element is brittle. Always remove the igniter prior to removing the fan assembly for inspection of the burner and heat
exchanger. A properly prepared igniter will have a bead of silicone sealing the end mounting bracket to the ceramic shaft. Ceramic gaskets
above and below the metal flange prevent the escape of hot combustion products.
Figure 32: Hot Surface Ignitor
During trial for ignition a properly operating igniter will generate 3.2+/-0.2A which is above the current required for reliable ignition. It is
recommended that the Hot Surface Igniter be replaced every 4,000 hours of appliance operation to maintain peak ignition efficiency.
7.2 UV SCANNER
The UV Scanner is screwed on a ½” NPT pipe nipple and is screwed into the fan flange. Care must be taken when installing the UV
Scanner, to align it parallel to the ½” NPT pipe nipple and not to over tighten. Always remove the UV Scanner prior to removing the fan
assembly for inspection of the burner and heat exchanger.
The ignition module relies on the UV Scanner to provide a flame rectification signal. Oxide deposits, improper placement or damaged
ceramic insulator will result in insufficient signal leading to ignition module lock out. For proper operation minimum 0.8 Vdc must be fed
back to the module. Oxide deposit on the detector window must be removed with a soft, clean cloth. The inside of the sight pipe must be
cleaned before re-installing the UV Scanner. The UV Scanner has a life expectancy of 40,000 hours.
7.3 STAGING RELAY
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