Rinnai · Tankless water heater

21 PC board data transfer error

High severity SENSEI RX/CXSENSEI

What the control is telling you

Data/parameter transfer to a PC board (typically a replacement board) did not complete correctly.

Applies to: SENSEI Series; SENSEI RX/CX Series

Likely causes

Data transfer incomplete after PC board replacement
Parameters not programmed correctly for the model
Board replacement/data transfer instructions not followed
Gas valve parameters missing or wrong (SENSEI RX/CX)

Test and repair steps

If the PC board was replaced, confirm the data transfer process finished.
Confirm all parameters match the water heater model installed.
Confirm the data transfer instructions were followed during board installation.
SENSEI If transfer failed, manually program all 14 parameters per the PC Board Replacement Instructions shipped with the new board.
SENSEI RX/CX If transfer failed, enter the gas valve parameters correctly per the Gas Valve Replacement Instructions (100000855) or PCB Replacement Instructions (100000854).

Settings for these units

RSC supply connection sizes · SENSEI

Connection	Size
Gas	3/4 in. NPT
Cold inlet	3/4 in. NPT
Hot outlet	3/4 in. NPT
Condensate drain	1/2 in. NPT
Pressure relief valve	M33 thread

The PRV and its adapter come in the box; PRV must be rated 150 psi and at least the heater Btu/h.

Condensate drain line must stay at least 1/2 in. over its whole length.

RSC water quality limits · SENSEI

Contaminant	Maximum level
Total hardness	Up to 200 mg/L
Aluminum	Up to 0.2 mg/L
Chlorides	Up to 250 mg/L
Copper	Up to 1.0 mg/L
Dissolved CO2	Up to 15.0 mg/L
Iron	Up to 0.3 mg/L
Manganese	Up to 0.05 mg/L
pH	6.5 to 8.5
TDS	Up to 500 mg/L
Zinc	Up to 5 mg/L

Damage from water above these limits is not covered by warranty.

Hard water should be treated; use the Service Soon (SS) reminder (parameter 03) for flushing intervals.

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

Models that show this code

30 models in SENSEI RX/CX, SENSEI

CU160eCU160iCU199eCU199iCX160iCX199iCXP160iCXP199iRSC160eRSC160iRSC199eRSC199iRU130eRU130iRU160eRU160iRU180eRU180iRU199eRU199iRUR160eRUR160iRUR199eRUR199iRX130iRX160iRX180iRX199iRXP160iRXP199i

Other codes on the same units

15 Venturi control fault
16 Outlet water over-temperature safety shutdown
17 Venturi blockage
18 Gas valve air/fuel adjustment limit reached
19 Electrical grounding / DC circuit short
22 Gas valve adjustment fault
25 Condensate pump failure or clogged drain
32 Outlet water temperature thermistor fault

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Source: Rinnai Troubleshooting TWH Diagnostic Codes (100000652), p.32. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

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.