Holdly Flammable Vapor Sensor Kit AP13447-3 (25VS) — Direct Replacement for Rheem/Ruud FVIR Heaters

The Holdly SP20172 kit contains the AP13447-3 (25VS) flammable vapor sensor plus a cap plug and wire tie, engineered as a direct replacement for Rheem, Ruud, Richmond FVIR water heaters to restore safety sensing and system operation.

This replacement kit provides the core sensing element used to detect gasoline and other flammable vapors near a water heater’s combustion chamber. When the original sensor fails or triggers false shutdowns, installing this AP13447-3 film sensor assembly can re-enable correct vapor detection so the control module can respond appropriately. The kit is compatible with many Rheem family units and selected AO Smith and Bradford White models — a straightforward parts swap that trained technicians or competent DIYers can perform following safety precautions.

How does the flammable vapor sensor work and why does it matter?

The sensor uses a thin vapor-sensitive film whose electrical resistance changes when it is exposed to flammable hydrocarbon vapors. The water heater’s control board monitors that resistance; if the measured value indicates dangerous vapor levels, the control cuts the gas supply to prevent ignition. It’s a passive sensing element that needs only the small monitoring current provided by the control circuit, not an external power source.

• Thin-film element reacts to gasoline and similar hydrocarbon vapors.
• Resistance change is read by the heater control board for safety decisions.
• No external battery or power supply required — uses control circuit current.
• Designed to trigger gas shutoff when dangerous vapors are present.

What comes in the Holdly SP20172 kit and how easy is it to install?

The kit includes the AP13447-3 (25VS) sensor, a rubber cap plug, and a wire tie for securing the assembly. Installation is typically a component-level replacement: remove the old sensor, position the new film sensor in the same location, secure with the supplied plug and tie, and reconnect the wiring to the same terminals. Follow manufacturer instructions and ensure gas and power are off before working on the heater.

• Contents: AP13447-3 film sensor, cap plug, wire tie.
• Direct-fit replacement for many Rheem/Ruud/Richmond FVIR units.
• Requires basic tools and adherence to safety procedures.
• Recommended for technician installation or experienced DIYers.

Which models and brands is this sensor compatible with?

Holdly’s SP20172 targets FVIR-style water heaters from the Rheem family — including Rheem, Ruud, and Richmond models — and is also used in certain AO Smith and Bradford White units where the AP13447-3 sensor was specified. Compatibility depends on the heater’s control board and sensor mounting; check your heater’s part number, service manual, or contact us with model details before ordering.

• Primarily compatible with Rheem, Ruud, Richmond FVIR water heaters.
• Also used in select AO Smith and Bradford White models.
• Confirm fit by matching your original AP13447-3 or 25VS part number.
• Contact Holdly with heater model for compatibility verification.

How quickly will replacing the sensor fix heater shutdowns?

In many cases, replacing a failed or contaminated sensor resolves false shutoffs immediately and allows the control board to read normal resistance values again, restoring gas flow and hot water once the control clears the error. If other components have been tripped or damaged, additional diagnostics might be necessary. Always reset error codes per the manufacturer’s procedure after replacement.

• Typical result: restores normal sensing and clears vapor-related shutdowns.
• May require control reset or power cycle to clear fault codes.
• Further diagnostics recommended if problems persist after replacement.
• Ensure proper mounting and wiring for reliable operation.

Who this is for: the Holdly SP20172 kit is intended for homeowners, HVAC technicians, and service professionals who need an OEM-style replacement for a failed flammable vapor sensor on Rheem/Ruud/Richmond FVIR water heaters or compatible AO Smith and Bradford White units. It’s a targeted repair part for restoring safety sensing and avoiding unnecessary downtime — order when your unit reports sensor faults or when the original sensor shows visible wear or contamination.