24 Volt Low
- Check line voltage. Must be between 100 – 128 volts.
- If available, connect a PC and, using HTP service software, check the 24v supply display in the lower left corner of the screen. The number displayed must be greater than 128 and should be greater than 250. Use this as a troubleshooting guide as you follow the steps below.
- Remove 10 pin Molex connector from customer connection board. If LOU clears, the problem is with external sensor wiring. Examine external sensor wiring for shorts to ground, repairing as necessary. If LOU code is still present and the heater is so equipped, disconnect high gas pressure switch, then low gas pressure switch, then UL 353 low water cutoff in this order, one at a time, to see if LOU code clears. Replace faulty part. Check low voltage wire harness in heater for shorts to ground.
- If LOU only occurs when burner tries to light, check gas valve for excessive current draw.
- If LOU is present with the low voltage harness disconnected from the 926 control board, replace the 926 control board.
