Ruud 93 Error Code
Faulty water flow solenoid
Source: hvac/ruud/c327d936__RUD-rutgh-84dvln-2_pm.pdf
What does Ruud 93 mean?
On Ruud RUTGH condensing tankless water heaters, error code 93 indicates a faulty water flow solenoid. The flow solenoid controls water flow through the unit; when the controller detects it is not functioning correctly, it displays code 93 and stops operation, because correct water flow is required for safe firing and temperature control.
Symptoms
- 93 shown on the remote control LED display
- Heater does not deliver hot water correctly
- Burner cuts out or fails to start
- Inconsistent flow or temperature before the fault
Common causes
- Faulty water flow solenoid
- Solenoid wiring or connection problem
- Stuck or failed solenoid valve
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Diagnostic steps
Note the code
Record that 93 is displayed; the flow solenoid is an internal component, not a user setting.
Power-cycle the heater
Turn off the faucets, turn off the heater, unplug it for about 30 seconds, plug it back in, restart, then recheck the display.
Confirm the code persists
If 93 returns after the power cycle, the water flow solenoid likely needs professional service.
Contact a dealer or qualified service technician
The manual's solution for code 93 is to contact a dealer or qualified service technician to test and replace the water flow solenoid.
When to call a professional
Call a dealer or qualified service technician for code 93. Diagnosing and replacing the water flow solenoid requires opening the unit and working near water, electrical, and gas components. The manual warns to make sure power is off before removing any protective cover and to refer repairs of electrical wiring and other safety devices to a qualified service technician.
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Other Ruud Error Codes
Lime/scale buildup detected — flush or descale the heat exchanger
Air intake or vent exhaust opening may be blocked
Vent pipes on the vent termination may not be connected properly
Gas shut-off valve is not fully opened
Gas service has been interrupted
LP gas is running low (LP models only)
Code still displayed after the basic recovery steps — service needed
Water heater is overheating
The heat exchanger is too hot
Neutralizer is clogged
Faulty inlet thermistor
Faulty outlet thermistor