dr or HEATER MAY BE DRY WILL RETEST SHORTLY Message
There is Possibly a "Dry" (dr) Heater.
On Heater Start Up, after successfully Passing the Sensor Sync Test, the Heater is Fired for 6.5 Seconds (at High Wattage*) or 18 Seconds (at Low Wattage*).
*Note: EL and VS systems are at High Wattage when running at 240V, Low Wattage when running at 120V. GL and GS systems are always at Low Wattage.
After the brief firing, the heater is turned off for 90 seconds. Throughout this time, the higher of the A and B sensors is continuously checked against the Pre-Heating Temperature.
If either A or B Sensor gets 4°F (2.0°C) or More above the Pre-Heating Temperature at any time during this wait, a Dry Heater fault is produced immediately, Indicating a Possible Dry Heater, or Not enough Water in the Heater to Start it. Heating is Disabled for 15 Min. or Press Any Button to Reset and Restart Heater Start Up.
If the panel has a Heat LED, it comes on "shimmering" for this stage. If the panel has an animated heat icon, the temperature icon jumps back and forth between a high thermometer reading and a low thermometer reading.
Check for Water Level, Flow Restrictions, Closed Valves, Air Bubbles, and Pump Prime, or Continue for a Detailed Test Procedure.