Rheem Tankless Water Heater E5 Error Code – Fixed

Why is your Rheem tankless water heater showing that error code E5? What does it even mean! Should you just call up a local plumber and get it over with? Not yet. 

Error E5 codes may be the result of a malfunctioning combustion alarm. In some cases, the error comes up when the water heater has a water flow rate that’s too high.

Fortunately, as a DIYer, you can quickly solve most of these issues without extensive technical knowledge. 

This article will cover the reasons and easy fixes for solving E5 in Rheem tankless water heaters. Are you ready to learn?

Why is an Error E5 Showing on my Rheem Tankless Water Heater? 

Water heaters display specific codes to represent an underlying issue. 

Rheem water heaters may function if the E5 error code is not severe. However, the water will not reach the desired temperature. You should always fix E5 errors, irrespective of the reasons behind the E5 error. 

Let’s explore the reasons why you keep getting error E5. 

Rheem Tankless E5 Code

High Water Flow Rate 

Is the heater not heating water? If you get the error code E5 and lukewarm water. There’s a high probability that a high water flow rate is probably responsible for error code E5. 

Water flow rates—the volume of water that gets heated within a minute—are an essential metric when selecting tankless units.

Gas-powered heaters have an average flow rate of five gallons per minute. In comparison, electric heaters can heat up to 2 gallons per minute flow rate. A higher than standard flow rate will not heat water. 

Bad Combustion Alarm 

Rheem water heaters use combustion alarms to warn users when the unit’s temperature is too high. A too-high temperature in the combustion chamber can increase pressure and cause heaters to explode. Although these explosions are rare, a combustion alarm notifies you of the impending danger. 

Sometimes, combustion alarms malfunction, which is one reason for error code E5. The defective alarm will beep every minute you open the tap. 

Main Burner or Pilot Problem 

You will get an error code E5 if the valve to the pilot or main burner is not open. Since water heaters require air to keep the pilot burning, a closed valve will shut off the air supply. Thus, you will end up with cold or lukewarm water instead of hot water. 

What Happens If I Ignore the Error Code E5 in a Rheem Tankless Water Heater? 

You can’t afford to ignore this code, as you run the risk of spending more to get a replacement for damaged parts. Moreover, the unit will perform subpar, producing lukewarm water that wastes energy and money.

A Rheem water heater may keep on working, despite an error E5. However, you will mostly end up frustrated with the unit’s performance. 

And let’s not forget the annoying beeping sounds from a faulty combustion alarm.  

How to Fix Error Code E5 in Rheem Tankless Water Heater Code 

It’s pretty simple fixing a majority of these issues behind error E5. However, it would be best if you got the right tools for a perfect DIY job. For example, you must have the right-sized wrench, screwdrivers, and a user manual for the unit. 

How to Fix High Flow Rate in Rheem Tankless Water Heater 

The water flow rate in tankless water heaters must not exceed 12.3 liters, or 3.25 gallons, per minute. To reduce the water flow rate, you must install low-water fixtures in various water outlets, from the showerhead to bathroom and kitchen sink faucets. 

In most cases, you need to get a replacement for old faucets. You may also reduce water flow by turning the water supply valve to an almost-closed position. 

How to Fix a Bad Combustion Alarm in Rheem Tankless Water Heater 

A blocked exhaust is often the reason behind faulty combustion alarms. To fix it:

  1. Check the vent pipes, especially where the vent termination links. 
  2. Examine if the venting is sealed and free of obstacles. You may contact a plumber to know if your vent meets the right criteria, such as vent length and proper diameter. 
  3. Move on to the blower motor if the vent has no problem. 
  4. Clean the air inlet filter, the heat exchange fans, and combustion air fans. Ensure the fan motor is functional.

How to Reset Rheem Tankless Water Heater System

Sometimes, you’ve checked everything up and down, twice, thrice, and again just to be sure, but there’s just nothing wrong. In that case, you may want to reset the heater instead. To do so:

  • Locate and switch on the water heater circuit in the electric panel. 
  • Remove the panel cover on the unit, and find the reset button. 
  • Push the button until it clicks into place and opens. 
  • Reconnect the gas valve. 
  • The water heater should regain its power supply. The reset button will cancel all error codes.