Rheem Power Vent: Pressure Switch Failed Open
On this page (6 sections)
The Short Answer: On a Rheem power-vent water heater with the Honeywell electronic control, “pressure switch failed open” (code 46, three flashes) means the control didn’t see the blower prove airflow, so it won’t open the gas. Rheem’s manual points to wiring, a blocked vent, and then the blower assembly. Clear the outdoor vent if it’s obviously blocked, then call a technician. Never bypass the switch.
What the pressure switch does
A power-vent heater uses a blower on top to push exhaust out through plastic pipe. Before the burner can light, the blower has to run and a pressure switch has to confirm there’s enough airflow. That is the heater’s protection against venting exhaust into your home. A blower thermal switch also opens if the blower overheats.
According to Rheem’s Technical Bulletin 1627 (opens in a new tab) and the power vent manual (opens in a new tab):
| Code | Flashes | Meaning |
|---|---|---|
| 46 | 3 flashes, pause | Pressure and/or blower thermal switch failed open |
| 45 | 6 flashes, then 2 | Lockout: blower pressure switch and/or thermal switch open |
| 44 | 2 flashes, pause | Pressure switch failed closed |
The bulletin lists a two-minute delay before a pressure switch fault is flagged.
Common causes
- Blocked vent termination: snow, ice, leaves, a nest, or a bush grown over the outdoor end.
- Vent problems: a disconnected joint, a sag holding condensate, or a vent run longer than the installation instructions allow.
- Pressure switch tubing: a cracked, kinked, or water-filled sensing hose between the blower and switch.
- Blower: a blower that runs slowly, has failed, or overheats and trips its thermal switch.
- Wiring: a loose or damaged connection at the switch or control.
The manual’s sequence is to verify the wiring, then check the vent for blockage, then replace the blower assembly.
What you can check safely
- Count the flashes and note whether you hear the blower start when the heater calls for heat.
- Go outside and look at the vent termination. Clear snow, ice, leaves, or debris from around it by hand.
- Look along any visible vent pipe for a separated joint.
- Make sure the heater is plugged in and the outlet has power.
- Unplug the heater and plug it back in once to clear a lockout. If the code returns, leave it off and call for service.
Don’t remove the blower cover or disconnect any tubing or wiring.
What the technician will check
A technician will watch the blower start and measure whether it creates enough pressure for the switch to close. They check the sensing tube for cracks or water, test the switch itself, and inspect the vent for blockage, proper slope, and length. If the blower is weak or its thermal switch is tripping, they replace the blower assembly as Rheem specifies.
Repair or replace
Clearing a vent, replacing a sensing tube or pressure switch, or replacing the blower assembly are all repairs. A vent that was installed too long or with too many elbows may need to be rerouted. Replacing the heater is only worth considering if the tank itself has failed.
Related: water heater blower not working, gas hot water heater power vent problems, and Rheem failed ignition lockout.
Frequently Asked Questions
Q: The blower runs but I still get the code. Why? A: A running blower isn’t necessarily moving enough air. A partly blocked vent, a cracked sensing hose, or a weak blower can all keep the switch from closing.
Q: It happens only in winter. What does that suggest? A: Snow or ice at the termination, or condensate freezing or pooling in the vent. Check the outside vent first, and have the vent slope checked if it keeps happening.
Q: Can the pressure switch be bypassed temporarily? A: No. It’s a safety device that keeps exhaust from entering the home.
Manuals and supporting references
These links distinguish general safety information from model-specific documentation. A manual directory helps you locate your unit’s instructions; it does not establish that every model uses the same parts, codes, or test values.
- Rheem Technical Bulletin TB 1627: PowerVent with Honeywell electronic control (opens in a new tab)Rheem PowerVent ESII storage heaters with the Honeywell electronic control.
- Rheem: 40/50-gallon power vent gas water heater Use & Care manual (AP23057) (opens in a new tab)Rheem power vent storage heaters covered by AP23057.
- Rheem: owner help and support (opens in a new tab)Identify the applicable model instructions or contact Rheem support.
- PG&E: recognizing and responding to a gas leak (opens in a new tab)Emergency actions for suspected fuel-gas leaks.
- CPSC: carbon monoxide fact sheet (opens in a new tab)Carbon monoxide hazards and emergency response.
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