30 Flammable vapor sensor activated or faulty

What the control is telling you

The flammable vapor sensor has tripped or failed; flammable vapors may be present near the water heater.

Applies to: RH180 (Hybrid Tank-Tankless Non-SENSEI Series)

Likely causes

• Flammable vapors present in the installation space
• Loose, damaged or broken sensor wiring or connectors
• Flammable vapor sensor mis-mounted or damaged
• Failed flammable vapor sensor
• Failed PC board

Test and repair steps

1. Warning: Vacate the room until safety personnel confirm the area is safe and all flammable vapors are removed.
2. Warning: Only technicians qualified to service gas water heaters should continue.
3. Disconnect power to the water heater.
4. Remove the front panel and inspect the flammable vapor sensor and its harness, from sensor to PC board, for loose, damaged or broken wires/connectors.
5. Confirm the sensor is mounted correctly and undamaged.
6. Only when certain no vapors are present, restore power and gas, open a tap and fire the unit.
7. Check D1 connector Red–Black pins (D) 1–6 = 1.9–2.1 VDC; White–Yellow pins (D) 4–3 = 25.5–39.5 mVDC.
8. If code 30 returns with no vapors present, replace the flammable vapor sensor; if still unresolved, replace the PC board.

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

Models that show this code

1 model in RH180 hybrid

Other codes on the same units

• 19 Electrical grounding / DC circuit short
• 25 Condensate pump failure or clogged drain
• 31 Burner thermocouple out of range
• 32 Outlet water temperature thermistor fault
• 33 Heat exchanger thermistor fault
• 34 Combustion air thermistor (Non-SENSEI) / Lime detecting thermistor (RX/CX)
• 35 Tank temperature sensor fault
• 38 Exhaust gas temperature sensor (CO sensor on RH180)