Rheem tankless water heater code E5 is an error, telling you that the desired water volume is too high. Mainly the heater is fail to reach the set water temperature due to the high flow rate.
As such, you will be required to slow down the volume of water passing through the system. In order to do this,
- You can slightly close the outgoing and incoming water valves.
- Or, reduce the simultaneous running hot water fixtures.
- Plus, adjust the water pressure regulator installed on your water lines.
- If not, install a water flow restrictor on the hot water outlet.
That’s not the end! After years of experience, I’ve discovered a few more nifty tips and tricks that really help me keep my Rheem tankless water heater running smoothly without exceeding its maximum flow rate..
Let’s dive right in and discover with me.
Table of Contents
What Does Rheem Tankless Water Heater Code E5 Mean?
Error code E5 on the Rheem tankless water heater is very common to the user while operating the system. Depending on the incoming water temperature and the kW of your heater, the E5 error mainly means that the flow rate is accessing the maximum requirement. For instance, your tankless water heater may fail to reach the set temperature as well.
In order to ensure the optimal temperature output and overall performance of your tankless water heater, it is essential to maintain the water flow rate at the recommended level.
If it is about the Rheem tankless water heater, it requires a minimum water pressure of 14 psi (97 kPa) and a minimum activation water flow rate of 0.4 gpm (1.5 lpm) to operate properly. Moreover, you need to ensure 40 (276 kPa) psi water flow to achieve maximum flow rate.
In case of an overflow of water, you will encounter an E5 error code on the remote display.
How To Fix E5 Error Code On Rheem Tankless Water Heater?
Before considering anything else, it will be wise if you can measure the water pressure of your water heater to confirm the fact. It will give you a clear concept of how much pressure you need to adjust to clear the E5 error code on your Rheem tankless water heater.
Anyway, to measure the pressure, you will need a water pressure gauge. If you don’t have one, purchase it from your nearby home improvement stores or online which will cost not more than $10-$15.
- You just need to attach the pressure gauge to any of the hot water fixtures nearby of your tankless water heater.
- Slowly open up that faucet. To get the correct reading, all other hot water taps in and outside of your home are turned off. Also turn off your washing machine, dishwater, and refrigerators with ice makers (if you have one).
- After turning on the hot water fixture, the needle on the gauge will start moving to a number that represents the water pressure in pounds per square inch or PSI. Simply note down the number on a piece of paper.
Now that you’re sure about high water pressure, the good news is that it is relatively easy to do yourself! Here we’re providing the 5 simplest methods to apply to adjust the water pressure to your tankless water heater at your requirement measurement.
1. Adjust The Water Pressure Regulator
When the term comes to adjusting the water pressure, I always prefer to head over to the installed water pressure regulator at my home. Yes! You get it right!
This is the common plumbing valve that would install right after the pipe from where the water is passing through to your household appliances including the water heater.
In case of high water pressure in your house, chances are it needs to be adjusted or repaired if needed. Here’s all you can follow:
How To Fix:
Here we’re going to tell you how to adjust your water pressure regulator for the exact water pressure that you need:
Step #1: First off, locate the water supply line that provides water to your water heater.
Step #2: Turn the valve to the Off position. Now find out the pressure regulator in a meter pit on the supply line.
Step #3: You will see a valve on the regulator made of brass that comes with a screw or bolt and a locking nut system.
Step #4: Simply take a wrench and loosen the locking nut. Now, turn the screw clockwise to increase the water pressure.
Step #5: Take your water pressure gauge and measure the water pressure again to see whether it is right now.
Step #6: If so, secure the lock nut in that place. Make the adjustment screw firmly attached to the assembly.
Step #7: Turn the main water valve back on and run a hot water faucet for a few seconds.
Step #8: Now head to the remote controller of your Rheem tankless water heater and the E5 error code should be erased from there.
2. Install A Water Flow Restrictor On Hot Outlet
When I found hot water from my water heater seemed to come out with too much force, I consulted Rheem technical support and they suggested me to install a water limiter on a hot water outlet. The method proved effective enough in the case of adjusting the water pressure in my water heater.
Well! You can install a water flow restrictor on the outlet connection of your tankless water heater as well. Even it will be a must-do if there is not any or have a malfunctioning water pressure regulator for your home water supply line.
It will effectively limit the maximum volume coming out of your water heater to a specified flow rate. Contact the Rheem manufacturer to learn about the right flow regulator for your Rheem tankless water heater model.
| Inlet Water Temperature GPM(LPM) | ||||
| 40°(4°C) | 50°F(10°C) | 60°F(16°C) | 70°F(21°C) | |
| 8kW | 1.0 (3.7) | 1.0 (3.7) | 1.0 (3.7) | 1.5 (5.7) |
| 11kW | 1.0 (3.7) | 1.0 (3.7) | 1.5 (5.7) | 2.0(7.6) |
| 13kW | 1.0 (3.7) | 1.0 (3.7) | 1.5 (5.7) | 2.0(7.6) |
| 18kW | 2.0(7.6) | 2.0(7.6) | 2.0(7.6) | 3.0(11.4) |
| 24kW | 2.0(7.6) | 2.0(7.6) | 3.0(11.4) | 4.0(15.1) |
| 27kW | 2.0(7.6) | 3.0(11.4) | 4.0(15.1) | 5.0(18.9) |
| 36kW | 3.0(11.4) | 4.0(15.1) | 5.0(18.9) | 5.0(18.9) |
- Go through the chart above to choose the right flow regulator for your water heater:
- Find out your tankless water heater input in the chart on the left.
- Now choose the column with the inlet water temperature closest to your geographical location.
- Note down the GPM or gallons per minute you find and match it with the corresponding water flow regulator model from the table below:
| Part Number | Maximum Flow Rate GPM(LPM) | Connection Size |
| ECO IFR1-2 | 1.0 (3.7) | 1/2″ Compression |
| 1.5 (5.7) | 1/2″ Compression | |
| 2.0(7.6) | 1/2″ Compression | |
| ECO IFR3-4 | 2.0(7.6) | 3/4″ NPT |
| 3.0(11.4)4.0(15.1) | 3/4″ NPT3/4″ NPT | |
| 4.0(15.1) | 3/4″ NPT |
Once you have purchased a flow limit, follow the steps below to install it on your hot water outlet:
Step #1: Start by turning off the water supply to your water heater by closing the supply valve.
Step #2: Disconnect the flexible supply line from the stop valve.
Step #3: Now take your new flow restrictor and connect the female thread end of the restrictor to the stop valve.
Step #4: Attach the flexible supply line to the other end of the flow restrictor.
Step #5: Turn the water supply back on and the water pressure to this hot water connection should be reduced. Also, you will be able to diminish the Error code E5 on your Rheem tankless water heater remote display.
3. Slightly Close The Incoming Or Outgoing Water Valve
As you already know, Rheem rtex-27 e5 code is mainly related to the high water flow rate in the system. For instance, you can easily reduce the flow rate through adjusting the water shut-off valves for your unit.
Simply head to the water shut-off valves for your water heater and slightly turn the valve lever to the Off position to slow down the volume of water passing through the system.
While handling the valve lever, make sure it is in well working condition. As most of the time, defective shut-off valves may cause water to pass to the unit in a higher flow rate.
Besides, check if multiple fixtures are running simultaneously. If that is so, reduce the number of fixtures flow rate of the unit. Don’t miss to check out the inlet and outlet pipes as well. It is recommended to keep water pipes 3/4-in. (1.9-cm) diameter or larger To allow the full flow capacity.
Now look at the display and see whether the E5 error code is still appearing or not.
4. Activate The Water Saving Control
Rheem tankless water heater equips a water-saving control feature that is designed to control the water flow to the unit. This is an essential feature of your water heater, especially when you’re using your heater in a drought area or anywhere water conservation is needed.
You will find this saving control inactive as a default setting. Thus you can use this feature to reduce the wastewater at the initiation of hot water demand by reducing flow to your unit.
For instance, you need to turn On this control. Follow the simple steps below to do so:
Step #1: Start by turning off the gas and water supply to your water heater. Turn off the gas and water shut-off valves.
Step #2: Remove the attached screws on the front cover panel of your water heater. When done, remove the cover panel and set it aside.
Step #3: Now locate the Dip switches assembly on the control board from the heater inside. Find out the DIP Switch 1 from the top-right portion of the control board. It will be labeled as the “DIP 1” on the top switch.
Step #4: Take a shape object and turn the third switch on “DIP 1” to the ON position (UP).
Step #5: When done, replace the front cover panel back in place.
Step #6: Finally restore the power supply to your water heater. And turn on the gas and water supply to your water heater by opening the shut-off valves. Head to the remote controller and the error code E5 should be eliminated.
5. Inspect The Water Flow Sensor
Water flow sensor is an essential element in every tankless water heater system that is designed to regulate the water flow in the unit. It also adjusts the proper amount of cold water mix flow to supply a stable hot water temperature at all times.
Basically, when you’re turning on the hot water fixture, this sensor recognizes it and measures the flow rate. The PCB is constantly monitoring all of these inputs and based on that, it decides how much power to send to the heating elements to heat the water.
Now in case, the flow sensor is defective and malfunctions, it will fail to send the right signal to the control board which leads to the Rheem electric water heater error code e5 on the control display.
How To Fix:
Turn off the power supply to your water heater. Also, stop the water and gas flow to your water heater by closing the shut-off valves.
Now remove the front cover to access the flow sensor. Visually inspect the flow sensor to see whether it is in well working condition. If needed, check out the continuity of the water flow sensor through the measuring voltage of the sensor wiring to the control board.
If there is a single malfunction, you need to replace it with a new one. It’s always best to contact the help center or call a professional to handle this replacement task in your water heater.
FAQs:
How to clear error code on a tankless water heater?
To clear the error code from the control panel, you need to reset the unit. For instance, turn off the power supply to your water heater and close the hot water fixtures. Wait for 5 minutes before turning everything back on.
What does error code 11 mean on the Rheem tankless water heater?
Rheem tankless water heater error code 11 mainly refers to failed ignition in the system. If there is no ignition, check the gas supply first. Ensure the gas line, meter, and regulator are sized properly. Also, check the status of the flame rod and igniter.
Is there any reset button on the Rheem tankless water heater?
No! There is no built-in reset button on the Rheem tankless water heater. You can reset the unit by flipping the circuit breaker to the Off position some time. Then turn it back. You can hard reset your Rheem water heater through dip switches.
In Closing
Rheem tankless water heater code E5 is a common error to the user that happens due to the high flow rate. Thus, when the LED shows this error, reduce the flow rate through the system until the LED display start reading the set temperature.
Start by slowing down the water valves or adjusting the pressure regulator to the maximum water flow requirement. Above all, we recommend installing a flow restrictor to maintain the water flow rate and to clear the error code E5 from your Rheem remote display.
Well!! That’s all here for you! While operating the heater. In case you encounter any more errors on your unit, check out our comprehensive Rheem tankless water heater error codes guide and get the easiest solutions!