Rheem Water Heater Pressure Switch Replacement — What This Part Does
The air pressure switch (also called a vent pressure switch) is a safety device that proves the blower is creating the correct draft before the unit will ignite. When the blower runs, it pulls a vacuum through a small sensing tube connected to the switch. If the switch sees the right pressure differential, it closes and signals the control board that venting is safe. The unit will not fire without that proof signal.
The switch can fail mechanically (stuck open or closed), its sensing tube can become blocked with condensate or debris, or the electrical contacts can corrode. More often, the fault is caused by blocked or undersized PVC venting, a failed blower, or a kinked/disconnected tube rather than the switch itself. Rheem’s blocked-vent fault bulletin explicitly ties this code family to vent restrictions and pressure-switch circuit problems, not just a bad switch alone.
Signs It Needs Replacing
- Blocked vent or pressure switch fault code (A06 or similar) The display shows a fault that Rheem documents as a blocked vent or pressure switch problem, and the unit locks out or will not attempt ignition.
- Blower runs but burner will not ignite You hear or see the blower motor spin up, but the main burner never fires because the control is not receiving the draft-proof signal.
- Unit shuts down mid-cycle or flame cuts out The heater starts normally but shuts off during a call for heat, often because the pressure switch opened unexpectedly due to a vent blockage or gust condition.
- Switch shows continuity when it should be open With the blower off and no draft present, the normally-open switch measures continuity across its terminals, indicating it is stuck closed.
- Switch will not close even with blower running The blower is creating draft, but the switch stays open when tested for continuity, proving it is mechanically stuck or electrically failed.
- Intermittent or wind-related shutdowns The unit faults only on windy days or at certain times, pointing to vent termination issues or a pressure switch that is overly sensitive or borderline.
How to Replace It
- Turn off electrical power to the water heater at the breaker or disconnect, and turn the gas supply valve to the off position.
- Remove the outer access panel and locate the pressure switch, a small round or rectangular component with a rubber sensing tube and a two-wire harness connector.
- Photograph the wire connector orientation and the tube routing, then pull the wire connector straight off the switch terminals.
- Gently pull the rubber sensing tube off the barb fitting on the pressure switch body (some units use a clip or push-lock fitting).
- Remove the mounting screw or bracket that holds the pressure switch to the blower housing or burner cabinet.
- Install the new pressure switch in the same orientation, secure it with the original screw or bracket, and press the sensing tube firmly onto the barb until it bottoms out.
- Reconnect the wire harness to the new switch, matching your photograph, and confirm the tube has no kinks or blockages along its entire run.
- Restore gas and electrical power, then monitor the first few firing cycles to verify the unit ignites normally and the fault code does not return.
- If the fault persists after switch replacement, remove the PVC vent piping from the blower outlet and attempt a firing cycle (with adequate combustion air) to isolate whether the problem is in the appliance or the external vent system.
The Part You Need
| Part | Notes |
|---|---|
| Rheem air pressure switch / vent pressure switch | Amazon | Gas and tankless models use different switch part numbers. Find your exact replacement by checking the model and serial plate inside the front panel or on the side of the tank, then cross-reference that model number with an OEM parts diagram or contact Rheem with your serial to confirm the correct switch assembly. |
Related Error Codes
If this part is failing you may also see one of these codes:
When to Call a Pro
If you are not comfortable working around live gas connections, flammable vapors, or 120 V AC wiring, hire a licensed plumber or gas technician. Rheem’s diagnostic procedure requires isolating the venting system (disconnecting PVC exhaust piping and running test cycles), checking blower operation, and verifying correct vent installation and sizing. All of those steps involve gas burner ignition, draft measurement, and combustion-safety knowledge. If the new pressure switch does not solve the fault, the real cause is usually blocked or incorrectly installed venting, a failed blower motor, a plugged sensing tube, or a control board issue. Any of those conditions require professional combustion analysis and vent-system inspection to prevent carbon monoxide hazards or repeat failures. For gas line, burner, or igniter work, or if you ever smell gas, stop and call a licensed technician.