Rheem Tankless Water Heater Error Codes (H103, E5, 45, 11, Etc.)

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Last Updated on: 11th December 2023, 07:27 pm

If you’re like me, you know the value of a good hot shower on a cold morning. And if you’re REALLY like me, you know that a tankless water heater is a way to go if you want to save money and space while still getting that sweet, sweet H2O.

But let me tell you. There’s nothing perfect in this world – not even tankless water heaters. Sometimes, they’ll start acting up and flashing these darn error codes. 

I’m not a rocket scientist, but I’ve spent enough time with Rheem tankless water heaters to learn about these codes. So, if you want to learn what’s up with those pesky little numbers, stick around, and I’ll break it down for you in plain ol’ English.

Also, proper maintenance can usually prevent many of these issues and make for a lot less troubleshooting.

Table of Contents

Error Code H103

When your Rheem tankless water heater displays error code H103, it indicates a problem with the high-limit switch. Specifically, the high-limit switch has been activated due to excessive heat in the unit.

The high limit switch is an important safety feature in the tankless water heater – it helps prevent the unit from overheating and causing damage or safety hazards. So if the high-limit switch has been activated, there’s a problem that needs to be addressed.

There are a few reasons why the high-limit switch might be activated. One possibility is a blockage in the water flow, which can cause the unit to overheat. Another possibility is an issue with the unit’s internal components, such as a malfunctioning thermostat or control board.

If you’re experiencing error code H103, the first thing to do is to turn off the unit and let it cool down for at least 30 minutes. Then, check for any blockages in the water flow and clean the unit’s air intake filter. If these measures don’t work, you may need to call a professional to check the unit’s internal components.

Error Code 5

When your Rheem tankless water heater displays error code 5, it tells you there’s a problem with the gas combustion. Specifically, the heater’s combustion chamber isn’t lighting correctly.

Now, there could be a few reasons why this is happening. One possibility is that there’s a blockage in the venting system, which is preventing the proper flow of air and gas. Another option is that the gas pressure is too low, preventing the combustion process. And finally, it could be an issue with the igniter or flame sensor.

Before fixing these issues, remember tinkering with gas appliances can be dangerous. So, if you need more confidence in your abilities, calling in a professional is always best. But if you’re brave and want to try, you should check the venting system first. Ensure there are no obstructions and that the vent pipe is installed correctly and terminated.

If that doesn’t solve the problem, you can check the gas pressure to see if it’s within the proper range. And if that still doesn’t work, it may be time to call in the pros. Whatever you do, don’t ignore error code 5 – it’s telling you that something’s wrong, and overlooking it could lead to more significant problems down the line.

Error Code 10

When you see this code on your Rheem tankless water heater, it means that there’s a problem with the ignition. Specifically, it means the heater detected a flame failure during operation.

Now, there could be a few different reasons why this is happening. One possibility is a blockage in the gas line or gas valve, preventing the proper flow of gas. Another possibility is an issue with the igniter or flame sensor. And finally, it could be an issue with the gas pressure being too low.

Error Code 11

When your Rheem tankless water heater displays error code 11, it indicates an issue with the ignition. Specifically, it means that the heater is failing to ignite or is having trouble staying lit.

Now, there are a few reasons why this might be happening. One possibility is a blockage in the gas line or gas valve, preventing the proper flow of gas. Another possibility is an issue with the igniter or flame sensor. And finally, it could be an issue with the gas pressure being too low.

If you’re feeling handy, try a few things to troubleshoot error code 11. First, check the gas line and valve to ensure no obstructions. Then, check the igniter and flame sensor to ensure they work correctly. You can also try adjusting the gas pressure to see if that helps.

Error Code 12

When your Rheem tankless water heater displays error code 12, it indicates a problem with the flame sensor. Specifically, it means that the heater isn’t detecting a flame when it should be.

Now, there are a few reasons why this might be happening. One possibility is a blockage in the gas line or gas valve, preventing the proper flow of gas. Another possibility is an issue with the igniter or flame sensor. And finally, it could be an issue with the gas pressure being too low.

If you’re up to it, you can try a few things to troubleshoot error code 12. First, check the gas line and valve to ensure no obstructions. Then, check the flame sensor to ensure it’s clean and positioned correctly. You can also try adjusting the gas pressure to see if that helps.

Error Code 13

When your Rheem tankless water heater displays error code 13, it indicates a problem with the incoming gas supply. Specifically, the heater isn’t getting enough gas to operate correctly.

Now, there are a few reasons why this might be happening. One possibility is a blockage in the gas line or gas valve, preventing the proper flow of gas. Another possibility is an issue with the gas pressure being too low. It could also be an issue with the gas meter or regulator.

First, check the gas line and valve to ensure no obstructions. Then, check the gas meter and regulator to ensure they work correctly. You can also try adjusting the gas pressure to see if that helps.

However, if you’re not comfortable doing this yourself, it’s always best to call in a professional. Messing around with gas appliances can be dangerous, and it’s always better to err on the side of caution.

Error Code 14

Error code 14 – now that one can throw you for a loop. When your Rheem tankless water heater displays error code 14, it indicates a problem with the thermal fuse. Specifically, it means the heater detected an abnormally high temperature in the heat exchanger.

Now, there are a few reasons why this might be happening. One possibility is a blockage in the heat exchanger, preventing proper water flow. Another possibility is an issue with the gas combustion, causing the heat exchanger to overheat. And finally, it could be an issue with the thermal fuse itself.

Whatever you do, don’t ignore error code 14. An overheating heat exchanger can lead to many problems, including poor performance, high energy bills, and even safety hazards. So if you see this code on your Rheem tankless water heater, don’t hesitate to take action. Your hot water – and your safety – are worth it!

Error Code 24

When your Rheem tankless water heater displays error code 24, it indicates a problem with the internal switch. Specifically, it means that the heater detects a malfunction with the flow switch.

The flow switch is essential to the tankless water heater – it tells the heater to turn on when hot water is needed. So if the switch is malfunctioning, that means the heater won’t be able to function correctly.

There are a few reasons why the flow switch might malfunction. One possibility is a blockage in the water line, preventing proper flow. Another possibility is an issue with the wiring or connections to the switch. And finally, it could be an issue with the switch itself.

Error Code 29

When your Rheem tankless water heater displays error code 29, it indicates a problem with the neutralizer drainage system. Specifically, it means that the heater has detected a failure in the drainage system for the neutralizer.

Now, the neutralizer is an essential part of the tankless water heater – it helps to neutralize acidic condensate before it’s drained out of the unit. So if the drainage system isn’t working correctly, acidic condensate could be building up inside the unit, which can cause all sorts of problems.

There are a few reasons why the neutralizer drainage system might be failing. One possibility is a blockage in the drainage line, preventing proper flow. Another possibility is that there’s an issue with the pump that’s responsible for moving the condensate out of the unit. And finally, it could be an issue with the neutralizer itself.

There are a few things you can try to troubleshoot error code 29. First, check the drainage line to make sure there are no obstructions. Then, check the pump to make sure it’s working correctly. You can also try resetting the unit to see if that helps.

Error Code 45

When your Rheem tankless water heater displays error code 45, it indicates a water leak somewhere in the unit. Specifically, the heater has detected water leaking from the heat exchanger or another internal component.

Now, a water leak is never a good thing, and it can cause all sorts of damage if left unchecked. So if you see this code on your Rheem tankless water heater, it’s vital to take action immediately.

There are a few reasons why the unit might be leaking water. A crack or hole in the heat exchanger or another component is possible. Another possibility is an issue with the connections between the different parts of the unit. And finally, it could be an issue with the pressure relief valve.

Error Code 61

When your Rheem tankless water heater displays error code 61, it indicates a problem with the combustion fan. Specifically, it means the heater has detected a malfunction with the combustion fan motor or wiring.

The combustion fan is an essential part of the tankless water heater – it helps supply the air needed for combustion. So if the fan isn’t working correctly, that means the heater won’t be able to function properly.

There are a few reasons why the combustion fan might malfunction. One possibility is an issue with the motor, such as a broken or worn-out component. Another possibility is an issue with the wiring or connections to the motor. And finally, it could be an issue with the control board.

Error Code 65

When your Rheem tankless water heater displays error code 65, it indicates a buildup in the solenoid valve. Specifically, the valve can’t open or close properly due to mineral buildup or other debris.

The solenoid valve is an integral part of the tankless water heater – it controls water flow through the unit. So if the valve isn’t working correctly, that means the heater won’t be able to function properly.

There are a few reasons why the solenoid valve might be clogged. One possibility is a buildup of mineral deposits from hard water. Another possibility is that there’s debris or sediment in the water supply. And finally, it could be an issue with the valve itself.

There are a few things you can try to troubleshoot error code 65. First, try cleaning the solenoid valve to remove any mineral buildup or debris. You can also try flushing the water heater to remove sediment in the water supply.

Error Code 76

When your Rheem tankless water heater displays error code 76, it indicates a problem with the communication between the unit’s control board and the remote control.

Now, there are a few reasons why this might be happening. One possibility is an issue with the wiring or connections between the control board and the remote control. Another possibility is that the remote control is malfunctioning. And finally, it could be an issue with the control board itself.

If you’re up to it, you can try a few things to troubleshoot error code 76. First, check the wiring and connections between the control board and the remote control to ensure everything is in order. You can also try resetting the unit and the remote control to see if that helps.

Error Code 94

When your Rheem tankless water heater displays error code 94, it indicates a problem with the combustion air fan. Specifically, it means the heater has detected a malfunction with the combustion air fan motor or wiring.

The combustion air fan is an essential part of the tankless water heater – it helps supply the air needed for combustion. So if the fan isn’t working correctly, that means the heater won’t be able to function properly.

There are a few reasons why the combustion air fan might malfunction. One possibility is an issue with the motor, such as a broken or worn-out component. Another possibility is an issue with the wiring or connections to the motor. And finally, it could be an issue with the control board.

If you’re uncomfortable doing this yourself, it’s always best to call a professional. Messing around with electrical appliances can be dangerous, and it’s always better to err on the side of caution.

Error Code 99

When your Rheem tankless water heater displays error code 99, it indicates a flue or venting system blockage. Specifically, it means that the heater can’t properly vent exhaust gases out of the unit.

Now, proper ventilation is crucial for the safe operation of any gas appliance, including a tankless water heater. So if there’s a blockage in the flue or venting system, exhaust gases could be building up inside the unit, which can cause all sorts of problems.

There are a few reasons why the flue or venting system might be blocked. One possibility is an obstruction in the flue, such as debris or a bird’s nest. Another possibility is an issue with the venting system, such as a damaged or improperly installed vent pipe.

First, check the flue for obstructions, such as debris or a bird’s nest. Then, check the venting system to ensure everything is installed correctly and in good condition.

Error Code E5

When your Rheem tankless water heater displays error code E5, it indicates that the water flow rate is too high for the unit to handle. Specifically, the heater can’t maintain the set water temperature due to the high flow rate.

Now, a high water flow rate can be caused by several things. One possibility is that multiple hot water fixtures are running simultaneously, which can exceed the maximum flow rate of the unit. Another possibility is that the flow sensor or control valve is malfunctioning.

If you’re experiencing error code E5, the first thing to do is check the hot water fixtures in your home to see if multiple fixtures are running simultaneously. If this is the case, you may need to reduce the number of fixtures in use or stagger their use to stay within the maximum flow rate of the unit.

If this isn’t the issue, check the flow sensor and control valve to ensure they work correctly. However, it’s always best to call a professional for this repair, as messing around with water and electrical appliances can be dangerous.

Error Code P1

When your Rheem tankless water heater displays error code P1, it indicates that the water flow rate is too low for the unit to operate correctly. Specifically, it means that the heater isn’t getting enough water flow to function properly and maintain the set water temperature.

Now, a low water flow rate can be caused by several things. One possibility is a blockage in the water inlet filter or the plumbing leading to the unit. Another possibility is an issue with the water pressure or flow rate from the main water supply. And finally, it could be an issue with the flow sensor or control valve.

If you’re experiencing error code P1, the first thing to do is check the water inlet filter and the plumbing leading to the unit to ensure there aren’t any blockages. You can also check the water pressure and flow rate from the main water supply to ensure they’re within the recommended range for the unit.

If everything is in order, you can check the flow sensor and control valve to ensure they work correctly. However, it’s always best to call a professional for this repair, as messing around with water and electrical appliances can be dangerous.

Error Code C2

When your Rheem tankless water heater displays error code C2, it indicates that the burner has been on continuously for more than one hour. Specifically, it means that the unit has detected that the burner has been on for an extended time, which can lead to excessive wear and tear.

Now, there are a few reasons why the burner might be on continuously. One possibility is a problem with the temperature control, causing the unit to constantly heat the water to maintain the set temperature. Another possibility is an issue with the thermostat or control board, causing the burner to stay on even when it’s not needed.

If you’re experiencing error code C2, the first thing to do is to turn off the unit and let it cool down for at least 30 minutes. Then, check the temperature control and thermostat to ensure they work correctly. You can also check the air intake and exhaust vents to ensure they’re clear of debris or obstructions.

Conclusion

Rheem tankless water heaters are great appliances for providing endless hot water, but they can sometimes experience errors that must be addressed. Error codes can help identify the problem’s root cause and take appropriate action. Always follow safety precautions and manufacturer instructions when troubleshooting and repairing your Rheem tankless water heater.

If you’re uncomfortable doing it yourself, it’s always best to call a professional to avoid safety hazards and further damage to the unit. Remember, addressing error codes can ensure that your tankless water heater operates efficiently and safely, providing you with a continuous hot water supply.