Rheem Tankless Water Heater Code 14 [Fixed]

Rheem tankless water heater code 14 is the error signalling to you that the overheat limiter has failed or the water heater has overheated and stopped working. In the high-efficiency model, error 14 tells you about a tripped high-limit switch due to the rising temperature of the unit. 

The major reasons for occurring this error code include:

  • Defective heat exchanger
  • Interruption in gas supply
  • Blocked or improper venting installation 
  • Faulty Molex connection 

In the event of this fault code, inspect the heat exchanger first for dirt build-up. Clean the blockage in the heat exchanger or replace it if it’s cracked. Inspect the venting for any blockages and remove the clog to prevent the unit from getting too hot.

Don’t be confused by just seeing the above previews. We have an ultimate guide for you to eliminate the error code 14 from your Rheem remote display.

rheem tankless water heater code 14

Possible Reasons & Solutions For Rheem Tankless Water Heater Code 14 [Quick Overview]

Before defining all the facts in detail, let’s make your further reading easier through the quick table below, highlighting all the probable reasons and recommended solutions for Rheem error code 14.

Probable ReasonsRecommended Fix
Rheem mid-efficiency tankless water heaterDefective Molex connectorVerify “U” connector is connected to Control Board
Gas supply issueEnsure the use of the right type of gas, gas size, regulator, flex line length for your water heater.
Blocked ventingEnsure the use of the right type of gas, gas size, regulator, and flex line length for your water heater.
Faulty or damaged heat exchangerCheck the heat exchanger for cracks and replace it if needed.
Faulty control boardReplace the control board if needed. 
Rheem high-efficiency tankless water heater Insufficient air flowClean out blockages from the air intake or exhaust vent. Ensure the correct venting installation of your water heater.
Scaled heat exchangerFlush your tankless water heater
Defective over temp switchReplace the faulty switch
Defective tankless water heaterReplace the unit.

How Do I Fix Error Code 14 On Rheem Tankless Water Heater?

In this section, I’ll share my first-hand experience on how you can diagnose all the obvious reasons and how to fix the error code 14 on both mid-efficiency & high-efficiency Rheem gas tankless water heaters. Let’s dive right in.

#- For Rheem Mid-efficiency Tankless Water Heater: Over Heat Limiter (OHL) Malfunction

First up, let me introduce the error code 14 on the Rheem mid-efficiency tankless water which actually means an activated or failed overheat high limiting film wrap sensor of the unit. 

An Overheat Limiting Film wrap is a safety device that is wrapped around the heat exchanger. It mainly prevents the overheating failure of the heat exchanger.

overheat high limiting malfunction

When the wrap sensor senses the excessive temperature of the heat exchanger, it immediately shuts the unit down to prevent further damage and throws an error code 14 as diagnostic information.

Various factors can be responsible for an overheated exchanger. Let’s track down all the factors and the effective ways to clear the code. 

1. Defective Molex Connector

In case of error code 14 on the mid-efficiency Rheem tankless water heater, the malfunctioning heater limiter  Molex connector at the control board is the root culprit to blame. While dealing with the same issue in my water heater, I discovered that the connectors weren’t secured in place. 

Beside this, you will find it damaged at all due to inappropriate resistance. Let’s track down all the factors through the below short test.

How To Fix:

Safety first! Make sure you have unplugged your tankless water heater from the power connection before handling any of the components of the heater inside. Now remove the front access panel and locate the control board.

Find out the white connector “U” on the Control Board. Remove and reinsert the connector and attempt to operate the unit again. Head to the remote display to see whether there is still an error code on the screen. 

If not, be sure you have a loose connection that you have already fixed. Start operating your Rheem water heater again.

But the error code 14 is still displaying, you need to measure the resistance between the connectors. For instance, remove the Molex connector “U” and Measure the resistance between both white wires. 

molex connector of rheem tankless water heater

In this regard, you should get a reading between 50K – 500K Ohms.

If the resistance to the OHL is okay, reconnect the Molex and attempt to operate the unit again. If there is any major malfunction in the Resistance reading, be sure the OHL has activated due to excessive temperatures. In this instance, there are a few more major factors that are responsible for this error code.

Head over to the below sections and figure out the actual reason for triggering the code on your control display.

2. Inadequate Gas Supply

If the Overheat film limiter of the Rheem water heater has activated, insufficient fuel supply to the unit can be one of the big reasons to concentrate on. In the case of the Rheem gas-operated tankless water heater, it requires an uninterrupted fuel supply to operate the unit efficiently. 

Due to an improper gas supply, creates a hot spot in the unit that results in activating the overheated film wrap right then.

Now for these instances, a higher possibility is you are using the wrong type of gas for your unit. Besides these, you may have:

  • Incorrect high and low fire manifold pressures
  • Blockage in the gas supply line
  • Air in the gas line
  • Gas shut-off valves are not opened all the way

How To Fix:

First off, you need to ensure that you’re using the right type of fuel for your unit. In the case of all gas tankless water heaters, the manufacturer recommends using a specific gas type, either it would be natural gas or LP.

Now take your manual and check out the gas type of your unit, and ensure it matches the gas type you’re using.

Next, inspect the gas supply line and ensure there is no stuck debris blocking the lines. If needed, bleed the air from the gas line and turn on the gas shut-off valve all the way.

 gas shut off valve

When done, measure the high and low manifold gas pressure of your water heater and check whether it requires additional adjustment. If you’re not clear on how to measure and adjust the high and low manifold gas pressure of a tankless water heater, the following effective video will surely help you a lot:

3. Blocked Venting

Inadequate air supply due to blocked venting is one of the major culprits that leads to the overheated film wrap sensor of the system. The air intake or exhaust vents might be blocked by soot, debris, birds, or insect nests, creating combustion issues. 

It is a quite common phenomenon for users if you’re not regular in proper maintenance of your tankless system. At times, users fail to ensure the correct venting installation as per the manufacturer’s instructions, which also leads to inadequate fresh air supply to the unit, resulting in error code 14 on the remote display. 

How To Fix:

Before heading over to clean out the ventilation of the tankless water heater, make sure you’ve unplugged your unit from the power connection. Now, inspect the air intake and exhaust vent for any blockages. 

Take a vacuum cleaner and insert the extension hose into the venting. Look inside the pipe and suck up the stuck debris from the venting. Use a vent-cleaning brush to clean out the soot.  In case you face trouble cleaning out the part that is harder to reach, you can use a duct cleaner to remove the debris.

 ventilation of rheem tankless water heater

When done, check and ensure the proper installation of the vents on your tankless water heater. Make sure that the vent materials, termination & lengths are according to the instructions in the Rheem manual. For better assistance, you can seek professional help.  

4. Faulty Or Damaged Heat Exchanger

If the overheated film wrap sensor fails due to overheating, a cracked or separated heat exchanger can be one of the big reasons. The heat exchanger is a set of metal coils that get heated directly by the combustion gas and fire. It is designed to transfer heat from the power source to the water.

heat exchanger of rheem tankless water heater

In case the heat changer is defective and separated from the connection, it fails to transfer heat to the water and gets too hot by itself. This overheats the unit and throws the error message 14 on the remote display. 

The heat exchanger can crack or be damaged due to long years of use or corrosion. At times, it occurs due to poor or improper manufacturing of the unit. Improper installation leads to cracks in heat exchanger fins. 

How To Fix:

If you suspect cracks or damages in the heat exchanger, we highly recommend not to head over for a DIY replacement or repair. If you are doing so, it may lead to life-threatening emissions. 

In this regard, it’ll be highly better to consult with a professional to examine the unit and let him suggest the best course of action. You may need to replace your damaged heat exchanger. 

5. Faulty Control Board

A defective or non-functional control board is another big reason for triggering the error code 14 on the Rheem tankless water heater. It will mostly be applicable when you notice that your unit shuts down due to the error code 14. 

rheem tankless water heater control board

The control board is like a central “brain” of a tankless water heater that is designed to control all of the functions of the system. Though it’s built to be durable, At times, it stops operating due to several reasons.

Either there is a loose connection in the control board or the board is defective itself. Also, the thing is that the older your tankless water heater is, the more the circuit board is vulnerable to malfunctions.

How To Fix:

Inspect the control board and determine any specific issue on the control board like loose wiring or faulty connectors. If so, fix the defects. In case of a defective control board, you just need to replace it to get back your heater into normal functioning.

#- Rheem High-Efficiency Tankless Water Heater Error Code 14: Overheat condition in the venting has triggered the Over Temp Limit Switch

The error code 14 on the Rheem high-efficiency tankless water heater mainly defines a triggered overheat limit switch due to rising temperatures in the unit. The error can be caused by several reasons. 

over temp limit switch of rheem tankless water heater

Here are all the reasons for triggering this error code with the effective solutions:

6. Insufficient Air Flow

Regardless of whether you’re experiencing overheating in your tankless water heater, the higher possibility is you have insufficient airflow in the unit.

A gradual loss of airflow from your tankless water heater can occur due to several reasons. Either the blower motor is functioning as it should or you might be experiencing blockage in the venting system. 

Let’s figure out the actual cause with the appropriate troubleshooting:

i) Defective Blower Motor

A blower motor is an essential element of a tankless water heater that is designed to blow the heated air out of the system. You will hear the spinning sound if the blower motor works efficiently. In case not, be sure the motor is defective. 

Either the problem is related to the faulty motor wiring connection to the control board or the element is defective.

Most of the time, it would be simply a clogged motor that prevents the fan from moving freely. As a result, the inside temperature of the unit keeps rising and triggers the high-limit switch.

How To Fix:

Unplug your water heater from the power connection first and remove the front access panel. Now inspect the blower motor for any obstruction. If so, remove it. Vacuum out the debris from the blower assembly using a vacuum cleaner. 

Now test the fan motor manual to see where it is moving freely. If not, you need to replace the defective blower motor. 

When done, head to the control board and check the wiring harness to the motor for damaged or loose connections.

Remove and reinsert the connector G on the control board. Next, you need to check for DC voltage to various wiring connections of the connector “G” as in the instructions in the below video:

ii) Blocked Venting

Clogged or improperly installed venting is one of the big reasons that results in restricted airflow in the system. If vents are contaminated with soot and debris, the combustion gas fails to pass out the system and also limits fresh airflow in the unit. 

When you have worsened the air quality in the heater, it will automatically overheat the unit and trip the high-limit switch.

As a solution we need to clean out the venting properly, we’ve already discussed the effective process to do so in section 1 of our article.

7. Blocked Heat Exchanger

If the entire temperature of your tankless water heater is gradually increasing which leads to tripping the high limit switch, the best chances are the heat exchanger is blocked. 

This is a common circumstance for the users who live in the hard water area. Over time, when you are using your water heater, the hard water passes through the heat exchanger and naturally dissolved minerals remain in the heating unit.

After a long time, the mineral turns into hard particles and insulates the heat exchanger. This insulation leads to overheating the unit since it has to work extra hard to reach the water at that set temperature and triggers error code 14.

How To Fix:

At the stage of troubleshooting, you need to remove the deposits from the heat exchanger. In this instance, flushing your water heater is an effective method to descale the mineral accumulation. If you’re wondering how to do so, you can check out our detailed guide to learn about how to flush a Rheem tankless water heater

rheem tankless water heater flushing

If you notice that the heat exchanger is beyond repair or cleaning, you may need to replace the heat exchanger as well.   

8. Malfunctioning Over Temp Switch

At times, a defective over-temp switch is the culprit that is triggering the error code 14 on the remote display. Improper resistance through the switch might be responsible for this issue. 

How To Fix:

You can test the high-limit switch electrically to confirm whether it is defective or not. In this instance, you’ll need a continuity tester or a multimeter to check out the continuity. 

Touch the probes from your multimeter to the high-limit switch of your water heater. A lack of continuity will indicate that the switch is faulty and you need to replace it.

9. Defective Tankless Water Heater

After resolving all the above responsive factors and still, there is the same error code on the control display, be sure the fault lies in your water heater. The best chances are your tankless water heater is defective and beyond repair. 

Generally, a tankless water heater lasts 15 to 20 years with proper maintenance and operation. With a copper tankless heat exchanger, the water heater can last 12-to-15 years. Anyway, once you’ve confirmed that your tankless water heater is not working anymore, nothing but you need to replace your unit.

FAQs:

What does error code 13 mean on Rheem tankless water heater?

Rheem tankless water heater error code 13 is a clear indication of incomplete combustion in the system. This is mainly caused by a dirty or broken flame sensor. Other major reasons include clogged ventilation, gas supply problems, poor ground connection, and so on.

Why does my Rheem tankless water heater keep turning off?

Your Rheem tankless water will shut down randomly when there is a loose or damaged wiring connection in the system. Also, you might be using too many hot water fixtures at a time that power off the unit fur to system overload.  

How to clean heat exchanger tubes from a tankless water heater?

Take a vacuum cleaner and remove the dust, dirt, cobwebs, and other debris from the heat exchanger tube. Then take a clean cloth dampened with a very mild detergent and wipe down the pipes and hoses associated with the heat exchanger.

In Closing 

Well! That’s all here about Rheem tankless water code 14. When you have an error code 14 in the control display while operating the unit, be sure it is a clear indication of the overheated system. In this regard, you need to inspect the heat exchanger, venting, and gas connection for any blockages and remove the clog by applying appropriate methods. 

Be cautious enough while operating the unit. If you’re technically inclined, we highly recommend getting help from Rheem technical support and let you perform the best troubleshooting action for this issue,

In case, you face any more fault codes in your remote display, find out with you through our comprehensive Rheem tankless water heater error codes guide. Here we have nicely organized each of the error codes and fixes that users most often face.

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