Rinnai error code 63 indicates that the recirculation flow rate has dropped below 1.3 gallons per minute, typically caused by clogged filters, trapped air, or a blocked pump.
Table of Contents
- What does error code 63 mean on a Rinnai tankless water heater?
- What usually causes Rinnai error code 63?
- How can you fix Rinnai error code 63 quickly?
- What are the next troubleshooting steps if the error persists?
- Which fix matches your specific error symptom?
- When should you stop troubleshooting and call a professional?
- What information should you have ready before calling a technician?
- How can you keep error code 63 from coming back?
What does error code 63 mean on a Rinnai tankless water heater?
Error code 63 means the recirculation flow rate has dropped below the minimum required threshold of 1.3 gallons per minute.
This specific fault code appears almost exclusively on Rinnai tankless water heater models equipped with built-in recirculation pumps or external recirculation setups. When the internal sensor detects water moving slower than 1.3 gallons per minute through the loop, the unit halts operation to protect the internal components from dry-firing or overheating.
- The error code specifically targets the internal recirculation loop performance.
- It triggers when circulation volume drops below 1.3 gallons per minute.
- The unit temporarily pauses heating to prevent pump motor burnout.
- It often appears during initial startup or after system maintenance.
- Confirm your exact model’s error definition using the manufacturer owner’s manual.
What usually causes Rinnai error code 63?
Error code 63 is usually caused by sediment-clogged water filters, trapped air bubbles in the recirculation line, or incorrect bypass configurations.
Over time, mineral scale and pipe debris accumulate inside the tiny mesh screens of the water inlet and bypass filters. Additionally, if maintenance was recently performed or plumbing work introduced air pockets into the loop, the pump fails to maintain steady pressure, prompting the controller to display error code 63.
- Sediment buildup blocking the inlet water filter or bypass filter.
- Air pockets trapped inside the recirculation piping or pump housing.
- Incorrect installation where the bypass plug was left in instead of a filter.
- Flow restriction caused by scale accumulation inside the heat exchanger.
- Low incoming water supply pressure feeding the recirculation loop.
How can you fix Rinnai error code 63 quickly?
Perform these safe preliminary actions to clear trapped air and restart your Rinnai tankless water heater properly.
Before diving into complex diagnostics, always turn off the power supply at the wall switch or breaker to prevent electrical shock. Follow these sequential steps carefully to reset the system and clear minor flow obstructions safely.
- Turn off the power switch and unplug the water heater from the electrical outlet.
- Locate the main water supply valve to the unit and turn it completely off.
- Open a nearby hot water faucet to relieve internal system pressure.
- Unscrew and remove the water inlet filter to check for trapped debris.
- Rinse the filter thoroughly under clean running water to remove scale.
- Reinstall the clean filter securely and close the hot water faucet.
- Turn the main water supply back on and check carefully for any leaks.
- Plug the unit back in, turn on the power switch, and press the error reset button.
What are the next troubleshooting steps if the error persists?
If initial fixes fail, inspect the bypass component configuration and bleed trapped air completely out of the recirculation line.
Persistent error code 63 codes usually point to hidden air locks or configuration mismatches in homes using a dedicated return line. Check your plumbing setup against the installation manual specifications to ensure the bypass components match your exact piping layout.
- Verify whether your setup requires a bypass filter or a solid plug.
- Inspect the recirculation line for hidden kinks, closed valves, or blockages.
- Bleed trapped air out of the pump housing using the manufacturer purge procedure.
- Measure the incoming water pressure to ensure it stays between 30 and 50 PSI.
- Inspect the wiring harness connecting the recirculation pump to the main control board.
Which fix matches your specific error symptom?
Match your exact physical symptom to the appropriate corrective action using this quick reference diagnostic table.
Different root causes behind error code 63 manifest with unique physical behaviors or system noises. Reviewing these common patterns helps you pinpoint whether the issue stems from simple debris, trapped air, or a failing pump component.
| Symptom | Likely cause / fix |
|---|---|
| Code appears after plumbing work | Trapped air; bleed the recirculation line. |
| Reduced hot water pressure | Clogged inlet filter; clean mesh screen. |
| Pump runs hot and cycles off | Low flow rate; check bypass configuration. |
| Code returns immediately after reset | Failing pump motor; test voltage or replace. |
When should you stop troubleshooting and call a professional?
Stop troubleshooting immediately and call a licensed plumber if you smell gas, encounter electrical issues, or suspect a failed pump motor.
Certain components inside a tankless water heater require specialized training and tools to service safely. For your safety and to protect your equipment warranty, recognize when a DIY fix crosses into professional territory.
- Stop immediately if you smell gas or suspect a gas valve leak.
- Call a professional if testing high-voltage internal electrical components.
- Contact a technician if the internal recirculation pump fails electrical testing.
- Seek expert help if descaling the heat exchanger does not clear the flow blockage.
- Never attempt unauthorized repairs on sealed gas combustion chambers.
What information should you have ready before calling a technician?
Gather your exact water heater model number, serial number, warranty status, and a list of troubleshooting steps already attempted.
Providing precise details to customer support or a local plumbing contractor helps them diagnose error code 63 faster and dispatch the correct replacement parts on the first visit. Check the metal rating plate on the side of your unit cabinet for accurate data.
- Locate the complete model number printed on the exterior rating label.
- Write down the unit serial number to verify active warranty coverage.
- Note the exact frequency of how often error code 63 appears.
- List all cleaning steps, filter checks, and resets you already tried.
- Confirm the installation date if available to help determine component age.
How can you keep error code 63 from coming back?
Prevent error code 63 from returning by scheduling annual filter cleanings, flushing the system for scale, and checking water pressure.
Routine preventive maintenance is the most effective way to ensure long-term reliability for tankless water heaters equipped with recirculation features. Establishing a seasonal upkeep schedule prevents mineral buildup from choking delicate flow sensors.
- Inspect and clean the water inlet and bypass filters every six months.
- Flush the heat exchanger annually with food-grade vinegar to remove scale.
- Test your home water pressure regularly to keep it within safe operating ranges.
- Ensure proper water softener maintenance if your home has hard water conditions.
- Review seasonal settings on your external controller or recirculation module.
Frequently Asked Questions
Can I still take a hot shower when my Rinnai shows error code 63?
In many cases, standard hot water usage will still function because error code 63 specifically impacts the recirculation loop rather than direct burner ignition. However, if the underlying flow restriction is severe enough, the unit may struggle to maintain a steady temperature. It is best to address the filter blockage promptly to restore full system efficiency.
What should I do if error code 63 comes back immediately after a reset?
If clearing the code and cleaning the filters does not resolve the issue, a physical restriction or mechanical failure is likely present. Check for closed service valves, trapped air pockets in the return line, or an obstructed bypass component. If those checks pass, the internal recirculation pump may require professional electrical testing or replacement.
Does error code 63 apply to non-recirculating Rinnai tankless models?
No, error code 63 is unique to Rinnai models that feature internal or external recirculation capabilities, such as the RUR series or units paired with a smart accessory pump. Standard non-recirculating tankless models utilize a different set of error codes for general water flow detection issues. Always check your specific owner’s manual to confirm code applicability.
How often should I clean the filters on a Rinnai tankless water heater?
You should inspect and clean the water inlet filter and recirculation bypass filter at least once every six months. If your home has hard water or well water with high mineral content, you may need to clean them every three to four months. Regular cleaning prevents debris accumulation from triggering low-flow errors like code 63.
Is a plumber required to fix error code 63, or can I do it myself?
Many homeowners successfully resolve error code 63 by turning off the power, removing the inlet filter, clearing trapped debris, and bleeding air from the system. You only need to call a licensed professional if these basic steps fail, or if you encounter electrical faults, gas connections, or a failed internal circulation pump.
Bottom Line
Turn off the power to your Rinnai tankless water heater and inspect the water inlet filter for debris first. Cleaning this mesh screen often restores proper flow and clears error code 63 immediately.
Sources
- Rinnai Owner’s Manual
- Rinnai Installation Guide
- Manufacturer Support Page