SERVICE HANDBOOK

ULTRA HIGH EFFICIENCY POWER VENT/POWER DIRECT VENT - SERVICE MANUALIGNITER CURRENT TESTThe water heater covered by this Service Manual uses a hot surface igniter (HSI). Thecontrol system CCB (page 35) powers the igniter (120 VAC) and monitors igniter current (ACamps). The more current flowing through the igniter; the hotter the igniter will be. The hotterthe igniter is; the more likely it will be to ignite the burner.The normal resistance of the hot surface igniter (when new) will be between 40-70 ohms at77°F (25°C). Hot surface igniters are wearing parts; with age and wear the resistance(ohms) of the igniter will increase. As the resistance (ohms) increases the current (AC amps)will decrease. More importantly the heat generated by the igniter will decrease at lower ampdraws. Over time hot surface Igniters will wear out and must be replaced as they will nolonger generate enough heat to cause ignition.The control system is programmed to verify a minimum of 2.0 AC amps before it will initiatea trial for ignition by energizing the gas valve (see Sequence of Operation page 40). If thecontrol system senses less than 2.0 igniter amps during the warm up period the controlsystem will lock out and display the “Low Igniter Current” fault message.Igniter current can be measured at CCB J5 socket or at the igniter. Clip the amp meteraround one of the two igniter wires to measure igniter current. See the images below.Service Notes - Hot Surface IgnitersIt is a good practice to check igniter current when any service or maintenance is beingperformed. Igniter current will be 4.0 to 5.0 AC amps when the igniter is new. Because hotsurface igniters are wearing parts they can cause intermittent ignition failure with age andwear. Replacing the igniter when current is lower than 3.0 AC amps is a good preventivemaintenance procedure that can prevent loss of hot water and customer dissatisfaction.Technical Literature Department 25 of 52 Ashland City, TN © 2008Servicing should only be performed by a Qualified Service Agent