Ruud Error Code 24: Flow Sensor Malfunction
How to Fix Ruud Code 24
- Step 1: Check the water supply to the unit. Make sure the main water valve is fully open.
- Step 2: Inspect the inlet water filter (if equipped) and clean it if it's clogged. Refer to your owner's manual for location and cleaning instructions.
- Step 3: If the problem persists after checking the water supply and filter, contact a qualified HVAC technician to diagnose and repair the issue.
How to Reset Ruud Code 24
- Turn off the furnace power switch, usually located on or near the unit.
- Turn off the circuit breaker for the furnace. Wait 30 seconds.
- Restore power at the breaker and flip the furnace switch back on.
- Set the thermostat to call for heat. If the error code returns after 2-3 ignition attempts, the fault requires repair.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Ruud Error Code 24 Mean?
The '24' error code on your Ruud unit indicates a problem with the flow sensor. This sensor is responsible for monitoring the flow of water through the heat exchanger. If the control board doesn't see the correct flow, it assumes there's a problem that could damage the unit, so it shuts down operation. This protects the heat exchanger from overheating. Specifically, the control board isn't receiving the expected signal from the flow sensor. This could be due to a faulty sensor, a blockage in the water lines, or even a problem with the wiring or the control board itself. Because the unit is locked out, you won't have hot water until the problem is resolved.
Common Causes
- Faulty flow sensor
- Scale buildup or debris obstructing water flow through the heat exchanger or flow sensor
- Wiring issues (loose connections, damaged wires) between the flow sensor and the control board
- Low water pressure to the unit
- Defective control board
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Unit displays error code 24 | Check the wiring connections at the flow sensor and the control board. Look for loose or corroded connections. | Connections are secure and free from corrosion. |
| Wiring appears OK | Measure the voltage signal from the flow sensor while water is flowing. Refer to the unit's service manual for the correct voltage range. | Voltage signal is within the specified range (typically 5V DC). |
| Voltage signal is out of range or absent | Check the flow sensor resistance with a multimeter. Refer to the service manual for the correct resistance range. | Resistance is within the specified range. |
| Resistance is within range but code persists | Inspect the heat exchanger for scale buildup or blockage. | Heat exchanger is free from significant scale or debris. |
Applicable Ruud Models
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Flow Sensor | — | — | — |
| Control Board | — | — | — |
Related Codes on Same Models
Other codes that affect the same Ruud model families as 24.
| Code | Description | Severity |
|---|---|---|
| 11 | No Ignition | Critical |
| 12 | Flame Failure | Critical |
| 13 | Improper Combustion | Critical |
| 14 | Overheat / Thermal Fuse | Critical |
| 15 | Inlet Temp Sensor Fault | Warning |
| 16 | Outlet Temp Sensor Fault | Warning |
| 21 | Air Supply / Operational Switch | Warning |
| 29 | Condensate Neutralizer Issue | Warning |
| 31 | Inlet Water Filter | Warning |
| 33 | Fan Motor Fault | Warning |