Rheem Tankless Water Heater Code 14 [Why+ How To Fix]

Rheem tankless water heater code 14 is the error indication of an activated overheated film wrap sensor. This mainly happens due to the rising temperature of the heat exchanger. The root reasons for this error code include: 

  • Using the wrong fuel type.
  • Cracked or broken heat exchanger.
  • Blocked vents.

Plus, the malfunction of the Molex connectors at the PCB and the clogged combustion chamber are the other two major reasons for this error.

rheem tankless water heater code 14

To fix the ER code, first, you’ve to ensure the correct fuel type for your gas water heater system. Next, inspect the heat exchanger for any damages. Clean out blocked venting. Test the Molex connector at the PCB and replace it if needed.

What Is Error Code 14 On Rheem Tankless Water Heater?

Error code 14 on the Rheem tankless water heater is mainly related to the Overheat Film Wrap. It functions as the heat limiter which monitors the heat exchanger temperature. 

The complete sensor is wrapped with black squiggly lines. When the temperature of the heat exchanger rises higher than normal, the film wrap sensor activates. 

An overheated heat exchanger causes the film wrap sensor to fail and you will find the error code 14 in the display.

Quick Solutions For Reasons Rheem Tankless Water Heater Code 14

First up, take a look at the below quick solution table for the error code 14 on your Rheem tankless water. It will make your further reading easier and quickly understandable.

Probable ReasonsPossible Solutions
Using the wrong fuel type> Ensure the correct type of fuel for your tankless according to the manual recommendation.
> Also, measure the high and low fire manifold gas pressures.
Cracked heat exchanger> Replace the broken heat exchanger. 
Blocked venting > Inspect the exhaust pipes for any clogs.
> Clean out the venting using a vacuum cleaner. 
Defective Molex connection> Inspect the Molex connections at the PCB.
> Remove the connectors and check the resistance going through them. If needed, replace the unit. 
Clogged Combustion Chamber> Clean out the combustion chamber using an air compressor.
> Also, blow the dirt from the burner. 

How To Fix Rheem Tankless Water Heater Error Code 14 [5 Easy Solutions]

Well! Now let’s dive into the in-depth exploration, highlighting all the responsive factors for error 14 with effective solutions.

rheem tankless water heater

“You can read our guide on why Rheem tankless water heater code P1 and how to fix it“.

1. Use Of The Wrong Fuel

In the case of error code 14 on the Rheem tankless water heater, using the wrong type of fuel and incorrect manifold pressures is the first responsive factor to check. 

Overall, almost all tankless water heater uses common fuel sources. That includes electricity, natural gas, and propane. A gas unit either uses natural gas or liquid propane for the ignition.  

Basically, it is determined through the manufacturer’s recommendation. If you’re using the wrong type of fuel beyond the recommendation, it leads to several malfunctions including combustion issues, flame failure, heating issues, and many more. Ultimately, you will get the error code 14 on the display. 

How To Fix:

  • As for the first step, check whether you are using the correct type of fuel for your tankless unit or not. 
  • To do so, go through the manual for your water heater. If there is any wrong, simply change the fuel type.
  • Next, you have to check the high and low fire manifold pressures of your tankless water heater and calibrate them if required.

How To Test The High & Low Gas Pressure In A Tankless Water Heater

Here are needed steps that you need to follow to check the gas pressure:

test the high & low gas pressure in a tankless water heater

#1- To test the gas pressure, take a monometer and turn it on. Let it set at 00 points. 

Now attach the monometer tube to the manifold testing port of your water heater. 

#2- Turn on the water valve and open all the hot water faucets to create the hot water demand.

#3- Now, remove the monometer tube from the monometer and block the tube end with the finger until the reading reaches 00. Then reattach the tube.

#4- Locate the manifold pressure adjustment buttons on the PCB of your water heater. Here you need to press and hold the top and third buttons from the top.

#5- Keep holding it until “S_P” pops up. Measure the high and low-pressure readings and compare them with the manual. If needed adjust the manifold gas pressure by pressing the minimum and maximum buttons.

2. Cracked Or Separated Heat Exchanger

If the overheat wrap sensor is not functioning, a defective heat exchanger is a leading culprit to blame. The best chances are either the heat exchanger fins have cracked or get separated from the connections. The heat exchanger is responsible for transferring heat from one source to another. 

rheem tankless water heater cracked or separated heat exchanger

When you turn on the hot water faucet, the activated heat exchanger heats the incoming water which rises the temperature. 

Also, if the heat exchanger is covered by dirt or shoots buildup, it gets too hot and causes the wrap sensor failure.

So, in this troubleshooting step, we should inspect the heat exchanger.

How To Do:

Before starting anything, don’t miss to turn off the power and gas supply to your water heater. It is the first safety precaution that you must have to apply. 

Now remove the front cover and inspect the heat exchanger. First, look for dirt or shoot build-up on the exchanger fins. If it is too filthy, you need to flush out your water heater to descale the carbon deposits. 

Draining and flushing out the tankless water heater is quite straightforward and you can do it by yourself. If you’re wondering how to do it, take a look at our dedicated guide to learn the detailed procedures

Anyway, after cleaning out the heat exchanger, check the fins for any cracks or damages. You need to replace the defective heat exchanger. In this case, you can hand over the task to a professional plumber. 

3. Blocked Venting

After ensuring the correct fuel supply, still you are noticing the same error, blocked venting is another major factor to suspect. Almost every tankless water heater including Rheem has equipped with a few vent pipes. 

rheem tankless water heater blocked venting

These are mainly used to exhaust the combustion gas and enter the fresh air to continue the ignition process. 

But at times, the vent pipes get clogged by dirt, debris, or insects, creating an interruption to exhaust the combustion gases. It backs to the heater and leads to the heat exchanger getting too hot. Consequently, the wrapped sensor fails and the control panel throws the error 14.

How To Fix:

  • Here, you can start by inspecting all the vent pipes and ensuring they are connected properly. Also, the exhaust vents should be free from any hard objects.
  • Next, check the pipes for any clogs. Take a vacuum cleaner and insert it through the venting port. Now vacuum out the entire inside area and remove all the dirt and debris.
  • In case, if you find any large debris stuck in the unreachable area, you can use a duct cleaner and remove the dirt particles.
  • Once cleaning is done, reassemble the vent pipe.

4. Malfunction In The Molex connections

Aside from the heat exchanger and venting issues, the defective Molex connection on the PCB is another root culprit behind the overheating film wrap at fault. On the PCB, all the Molex connections go to one location and fit one way. 

malfunction in the molex connections of rheem tankless water heater

Now if any of the Molex connectors get loosened and detached from the PCB, it leads to the wrap sensor failure. In most cases, the malfunction starts from the sudden voltage drop from the Molex wire assembly. Consequently, the heater displays the error code 14. 

So, in this step, you need to check the resistance of the Molex connectors. 

How To Do:

Follow the below step-by-step instructions to test the connectors:

Step #1: Start by turning off the power supply to your water heater. Also, turn off the gas shut-off valves.

Step #2: Remove all the screws that are securing the front cover of the unit. Disconnect the front cover and set it aside. Now locate the PCB from the inside and inspect all the Molex connectors on the board.

Step #3: First off, check to see whether the Molex connector at location U get detached or loosened. If yes, secure the connection and restart the unit.

Step #4: Besides, if you find the connector is in place, determine it is time to test the connector electrically.

Step #5: Remove all Molex from the connector. Now measure the continuity of connector U between both white wires. It should give a reading of 50k – 500k ohms. If not, you need to replace the bad connectors.

Step #6: In case the resistance is all ok to the connector, then the problem lies in PCB. Replace the bad PCB.

5. Foreign Materials In Combustion Components

In most cases, the combustion chamber gets clogged with foreign materials. Consequently, the heat exchanger malfunctions. Due to an overheated heat exchanger, the Overheat Film Wrap fails & the display shows the error code 14.

Rheem tankless water heater combustion chamber gets clogged

Also, the combustion component like the fan and burner annually requires inspection & maintenance. If it is so long to inspect and clean our tankless unit, it is confirmed that it is the reason for this error code. 

How To Fix:

Just follow the below few phases to clean the combustion chamber:

Phase #1: Start by unplugging the electrical cord from the power outlet or at the circuit breaker. Also, turn the gas shut-off valve clockwise to stop the gas supply.

unplugging the rheem tankless water heater electrical cord

Phase #2: Unscrew all the screws from the top panel. Remove the cover panel and set it aside. 

Remove the rheem tankless water heater  cover panel

Phase #3: First up, remove the screws that keep the burner to the combustion chamber in place as you can see in the picture below.

remove the screws from burner to the combustion chamber

Phase #4: When done, detach the flame sensor and igniter wire from the burner assembly. Now, pull out the burner.

pull out the rheem tankless water heater burner

Phase #5: Take an air compressor. Blow out all the stuck dirt and debris from the top and inside of the burner assembly. 

Blow out all the stuck dirt and debris from the burner assembly

Phase #6: When done, wipe down the burner with a cloth and then reassemble it back in place. But before that, don’t forget to inspect the combustion chamber as well. Blow away dirt & dust from the chamber using the compressor. 

put back the rheem tankless water heater front cover panel

Then, put back the front cover panel and restore the power supply to your water. Now check for error codes. 


How do you clear the error code 14 on Rheem tankless water heater?

First up, figure out the all responsive factors for the code and fix those. Then, simply reset the circuit breaker unit and the power cord. This will erase the code from the display.

Why is my Rheem tankless water heater overheating?

Restrictions in the air supply or blocked exhaust venting are the root reason for a tankless unit overheating. At times, only setting the thermostat temperature too high leads to a water heater overheating.  

How much does it cost to replace the heat exchange in a tankless water heater?

The average cost for the replacement of the heat exchanger is around $500-$1500. Then you will expect to pay up to $200-$300 if you hire a professional for the replacement job. 

In Closing!

Well! That’s all from us here about Rheem tankless water heater code 14. Whenever you are encountering this error code, look for the cracked or broken heat exchangers as it is the leading factor for the faulty film wrap sensor.

Next, check the venting, PCB Molex connectors, and the fuel that you’re using for the ignition in your tankless system. Anyway, we have explored each of the troubleshoots in detail throughout our guide. 

After thoroughly reading, hope that there should be no queries left over on this error code. Still, if you want to know more, do let us know through comments. We’re always here for you.

About William

William is the founder of Fireplacehubs.com. He has real life practical skills in fixing smoker & heating appliance issues. He loves to share his knowledge & helps others in fixing their appliances & saving their money. William firmly believes that anyone can repair his or her unit with the correct guidance & knowledge. See more at about us.

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