Rheem RUUD AdvantagePlus

This document outlines troubleshooting procedures for the Rheem/Ruud AdvantagePlus water heater, focusing on various operational and diagnostic aspects. It serves as a guide for technicians to identify and resolve common issues, ensuring the unit operates efficiently and safely.

Function Description

The AdvantagePlus water heater is designed to provide hot water, incorporating several safety and control features. Its core function involves heating water and maintaining it at a set temperature, while continuously monitoring various parameters to ensure safe operation. The unit utilizes a control board that integrates multiple sensors and relays to manage the heating process, combustion, and safety interlocks.

Key operational components include:

Line LED: Indicates the presence of 120VAC line voltage to the control board. If this LED is off, the unit is not receiving power, preventing any operation.
24 VAC LED: Monitors the voltage from the transformer, indicating if secondary 24VAC is present. This voltage is crucial for the control board's operation and various low-voltage components.
ECO/VENT SWITCH LED: This LED monitors the ECO (Emergency Cut-Off) loop, which includes the tank water over-temperature switch, the low water cut-off switch, and the vent over-temperature switch. When this LED is ON, all three safety devices are in their normal, closed state, allowing the unit to operate. If any of these devices trip, the LED will turn off, and the unit will cease operation to prevent unsafe conditions.
GAS VALVE LED: Indicates when power is applied to the gas valve. This LED illuminates when the control board attempts to open the gas valve to initiate combustion. The unit monitors for flame rectification (the presence of a main burner flame) after the gas valve opens.
PRESSURE SWITCH LED: Monitors the positive air pressure switch, indicating if there is sufficient combustion airflow. This LED is ON when the pressure switch is closed, signifying adequate airflow through the venting and blower system. If there's insufficient airflow, the LED will turn off, and the unit will not fire.
COMB BLOWER LED: Indicates when power is supplied to the combustion blower motor. The blower is essential for drawing in combustion air and expelling exhaust gases.
IGNITER LED: Monitors the igniter element output. This LED is ON when 120VAC power is applied to the igniter, which is responsible for igniting the gas.
WATER TEMPERATURE LED: This LED is associated with the thermistor that monitors the water temperature inside the tank. It turns ON when the water temperature drops below the set point, signaling the unit to begin or attempt to fire off to heat the water.
CONTROL HEALTH: This is a self-diagnosis feature of the control board, indicating the overall health of the system.

Usage Features

The AdvantagePlus water heater is designed for user-friendly operation with built-in diagnostic capabilities to assist in troubleshooting.

LED Indicators: The various LEDs on the control board provide immediate visual feedback on the status of critical components and safety interlocks. Technicians can quickly assess the operational state of the unit by observing which LEDs are on or off.
Reset Button: A red reset button on the front panel allows for manual reset after a lockout condition, such as an ECO trip or ignition failure. This enables the unit to re-attempt operation after a fault has been addressed.
Display Panel: The display panel provides information such as water temperature and set point. It also allows for setting the desired water temperature. In case of a lockout, it may display "LOC," indicating a fault condition.
Troubleshooting Flowcharts: The manual provides detailed flowcharts that guide technicians through a systematic diagnostic process based on the status of the LEDs and other observable symptoms. This structured approach helps in pinpointing the root cause of a problem efficiently.
Continuity and Voltage Checks: The troubleshooting steps frequently involve measuring voltage (e.g., 120VAC, 24VAC, DC control voltage) and continuity across various components (e.g., switches, probes, wires). This requires the use of a multimeter.
Resistance Chart: A resistance chart for the thermistor is provided to help verify the water temperature probe's functionality by measuring its Ohm resistance at different temperatures.

Maintenance Features

The design of the AdvantagePlus water heater and its diagnostic tools facilitate maintenance and repair.

Modular Components: Many components, such as the control board, transformer, igniter, and various switches (pressure, ECO, low water cut-off), are designed to be replaceable modules. This simplifies repairs by allowing technicians to swap out faulty components rather than performing complex repairs on individual parts.
Accessible Wiring: The wiring connections are generally accessible, allowing for easy inspection, testing, and replacement. For instance, Molex plugs are used for secure and easy connection/disconnection of wiring harnesses.
Venting System Diagnostics: The manual provides extensive guidance on diagnosing issues related to the venting system, including checks for blockages, proper piping, and termination. This is crucial for ensuring safe combustion and exhaust.
Gas Supply Diagnostics: Steps are included to verify gas pressure and fuel supply, addressing potential issues with the utility meter, service lines, regulators, and piping. This ensures the unit receives an adequate and consistent gas supply for proper operation.
Combustion Quality Check: The manual recommends adjusting the AdvantagePlus using a CO meter to ensure optimal combustion and prevent premature igniter or burner failure.
Component-Specific Checks: Each major component (e.g., igniter, blower, gas valve, temperature probe) has dedicated troubleshooting steps, including specific measurements and visual inspections, to verify its functionality.
Polarity Check: The presence of a green LED on the control board indicates correct polarity of the incoming 120VAC. If this LED is off, it signals a polarity issue, which is a critical safety concern and must be corrected.
Water Quality and Flow Rate: For issues related to temperature holding, the manual suggests verifying the water flow rate and inspecting the ECO/Temperature probe for damage, which could lead to false signals.

Overall, the AdvantagePlus troubleshooting guide emphasizes a systematic approach to diagnosis, leveraging the unit's built-in indicators and requiring standard electrical and plumbing measurement tools to ensure safe and effective resolution of operational issues.