HVACopediaRinnai · Tankless water heater
SE Cascade diagnostic display (error on secondary unit)
What the control is telling you
In a cascade of commercial units, the primary heater's display alternates between SE and the set temperature whenever any secondary heater is showing an error code.
Applies to: SENSEI Commercial and SENSEI CX Series (cascade installations)
Likely causes
- An error code is active on a secondary water heater in the cascade
- Primary unit relaying a fault from a cascaded secondary unit
Test and repair steps
- Note that SE appears only on SENSEI Commercial and SENSEI CX Series units connected in cascade.
- When the primary unit flashes SE and the set temperature, check the secondary heaters to find which one is displaying an error code, then troubleshoot that code.
Settings for these units
- RSC supply connection sizes · SENSEI
- RSC water quality limits · SENSEI
- RSC clearances to combustibles · SENSEI
- RSC temperature settings available · SENSEI
- RX supply connection sizes · SENSEI RX/CX
- RX water quality limits · SENSEI RX/CX
- RX water treatment and flushing by hardness · SENSEI RX/CX
- RX clearances to combustibles · SENSEI RX/CX
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Source: Rinnai Troubleshooting TWH Diagnostic Codes (100000652), p.65. Summarized in our own words; check the original manual for your model.
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For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.