Rinnai Tankless Water Heater: Checking PC board fuses and thermistors

Checking PC board fuses and thermistors on a Rinnai tankless water heater: How the guide says to test the board fuses and the temperature sensors with a meter.

Homeowner with a tankless water heater problem? Call (647) 657-2977 or book a service call — licensed technicians across Vaughan and the GTA.

Applies to: SENSEI RX/CX (RX199i, RX180i, RX160i, RX130i, CX199i, CX160i, RXP199i, RXP160i, CXP199i, CXP160i)

Common causes of checking pc board fuses and thermistors

• Blown glass fuse on the PC board
• Thermistor open, shorted or out of range

How to fix checking pc board fuses and thermistors: step by step

1. Disconnect power first, then pull each of the two glass fuses on the PC board and test continuity; no continuity means the fuse is blown and must be replaced.
2. Unplug the thermistor connector and measure on the 20 k range at the thermistor side.
3. Warm the sensor bulb: resistance should fall. Cool it with ice: resistance should rise.
4. Compare readings with the typical temperature/resistance table.

If the unit shows an error code, look it up: Rinnai Tankless Water Heater codes

Models

Non-SENSEI

C199eC199iR50LSiR63LSe2R75LSeR75LSiR94LSeR94LSiR98LSeR98LSe-ASMER98LSiR98LSi-ASMERC80eRC80iRC98eRC98iRE140eRE140iRE160eRE160iRE180eRE180iRE199eRE199iREP160eREP160iREP199eREP199iRL75eRL75e(A)RL75iRL75i(A)RL94eRL94iRLX94iRU80eRU80iRU90eRU98eRU98iRUC80iRUC90iRUC98iRUCS65iRUCS75iRUR98eRUR98iRUS65eRUS75eV53DeV53eV65eV65iV75eV75iV94eV94iV94Xi

SENSEI

CU160eCU160iCU199eCU199iRSC160eRSC160iRSC199eRSC199iRU130eRU130iRU160eRU160iRU180eRU180iRU199eRU199iRUR160eRUR160iRUR199eRUR199i

SENSEI RX/CX

CX160iCX199iCXP160iCXP199iRX130iRX160iRX180iRX199iRXP160iRXP199i

RH180 hybrid

RH180