Rheem Tankless Water Heater Troubleshooting Manual!

By - Rajib Ahmed

Updated -

A water heater that works well is essential in the home, and introducing a tankless water heater improves your access to hot water.

Using a Rheem tankless water heater, you get hot water at all times to do whatever you want in your home. It saves you money and time and is energy-efficient.

However, if there’s a problem with your Rheem tankless water heater, say you have an error code displaying, what do you do with the code?

In a Rheem tankless water heater, there are several issues you can experience. These issues range from the heater not turning on or shutting down to the fuse blowing up. However, you can also get error codes and, with these codes, troubleshoot what they mean. Some of these errors you can fix, and others you need help fixing.

In this article, I’ll explain the problems you can encounter with your Rheem tankless water heater and how you can troubleshoot them.

By the end of this article, you’ll know what to do whenever you experience a problem with your Rheem tankless water heater.

What Is the Principal Information in the Rheem Tankless Water Heater Troubleshooting Manual?

Rheem Tankless Water Heater Troubleshooting Manual

In a Rheem tankless water heater, there are typical problems you experience and knowing what to do in this case is vital.

This knowledge can save you money and time because you can fix problems yourself. 

However, this might only sometimes be the case, and you might need help fixing some complex problems.

Even if you can’t fix an issue, the good thing is when these problems arise, you know what you are dealing with and what to do.

Here are some problems you can experience with your Rheem tankless water heater and helpful information about them.

  • Inability to turn on.
  • The heater blows a fuse.
  • Low flow problem
  • Water is not hot

#1. Inability to Turn on

If your Rheem tankless water heater doesn’t turn on, you should check if it’s properly connected to a power source. It will only work if you connect it to electrical power.

Sometimes, it is about something other than connecting it to electrical power. 

For example, if the plug is connected and it still doesn’t work, you should check if there’s current flowing in the socket.

Also, your heater won’t turn on if it’s in maintenance mode. However, you can rectify the problem of your heater not turning on.

Ensure you properly connect the plug to a power source and that there’s current flowing in the power outlet. Check that your circuit breaker does not trip to be sure the fault is not from there.

Also, ensure it is not in maintenance mode. If it is, access the maintenance mode by pressing the button’s arrow up and down together for a few seconds.

Next, you’ll hear a beep and receive an oE message on the control panel. Then press either the arrow up or down to access the machine’s information.

Check if everything is working well, like the wires being intact in the junction box and the voltage in the PCB and transformer is okay.

#2. The Heater Blows a Fuse

If your connection is wrong or you have loose wiring, it can result in your heater blowing up a fuse. Another reason is if the thermostat wiring keeps touching itself.

You can rectify this situation by ensuring the wires do not touch each other. If it’s a wire causing the fuse to blow up, you can test the wires going into the thermostat with a multimeter.

Check the wires for a short circuit. Use the correct wire size for your heater and ensure no loose wires result in the fuse blowing up.

Also, change the fuse, then press the red button behind your Rheem water heater to reset it.

#3. Low Flow Problem

You sometimes notice that when you use your Rheem tankless water heater, it doesn’t flow well. It might be because there are clogs in its inlet filter, which causes the flow to be low. 

It can also be because the water valve or flow sensor is faulty. Improper installation of hot and cold water can also be the cause.

You can fix a low-flow problem by cleaning the water filters so there are no clogs. If after cleaning you notice that’s not the cause, replace the flow sensor or change the water valve.

You should use professional help installing your tankless water heater, so everything is okay when installing the cold and hot water lines.

#4. Water Is Not Hot

If your water heater is not getting hot, this is a significant problem you must fix. Your heater is experiencing this problem because you have a clogged air supply system or exhaust.

When this happens, the heater shuts off and will not work to prevent hazards so that it won’t heat the water, producing cold water.

Your heater might not get hot because you use too many hot water outlets simultaneously. It can also be a sediment build-up in the plumbing system or a defective ignition system.

You can fix this problem by unclogging the exhaust system or cleaning your plumbing system to rid it of the sediment build-up.

You should also reduce the number of hot water outlets you use simultaneously.

How to Troubleshoot a Rheem Tankless Water Heater?

If you want to troubleshoot your Rheem tankless water heater to know the problem, you should know the model to pinpoint the solution.

The solution for one model might not work for the other, so when troubleshooting a Rheem water heater, knowing the model is vital.

When troubleshooting a Rheem water heater, you must note the error code you’re getting, as that can give you an idea of the problem.

The table below shows a list of error codes you can get in a Rheem tankless water heater and how to fix it.

Error CodeDescription Fix
00The system works for over an hour without stopping.Shut the hot water taps and replace or off the circulation pump.
03.A manifold control problem. It happens in MIC-180 or EZLink.Install the MIC-180 or EZLink correctly.
05Imperfect combustions. The heater is dirty and blocked.Clean the air filter, air fan, and all the places dirt can block.
10.Detect false flames coming from the system.Check that all vents are clear and nothing is blocking them.
11No ignition. Low gas pressure and a faulty igniter can cause it.Check that the igniter for damage. A professional should help fix it.
12Flame failure. The heater cannot sustain a flame.Check if the gas valves are open and if there is proper grounding.
13Improper combustions. It occurs when the flame rod has a problem.Check if the flame rod, vent, and exhaust work and ensure no block.
14Overheat wrap fault. The use of the wrong gas can cause this.Ensure you always use the correct gas.

There are many other error codes you get when there’s a problem with your Rheem tankless water heater that you can use in troubleshooting it.

The table only lists a few error codes, but you can read more about Rheem’s error codes.

What Are the Most Common Problems with Rheem Tankless Water Heaters? 

Several problems can cause a hiccup in how your Rheem tankless water heater functions. 

Here are some common problems with a Rheem tankless water heater;

  • The water is too hot.
  • Foul odor.
  • The water is brownish.
  • The water heater shut off.

#1. Water Is Too Hot

You want your Rheem heater to produce hot water, but producing extremely hot water is bad. It might be because of the heating temperature or thermostat problem.

For example, if you increase the theater’s temperature, you might have set it too high, which makes the water hot. At other times, it can be because of a thermostat problem.

You can test the thermostat to know if that is the problem. Then, you can request the help of a technician to fix it.

#2. Foul Odor

Sometimes, you discover that the water from your heater smells. What could be the cause? Bacteria cause this problem; however, you can quickly fix it.

Turn your heater’s temperature to 135-140°F to rid it of the bacteria causing it to smell. Then, after the water has cooled down, flush out the water from the tank till it’s empty.

#3. The Water Is Brownish

Brown water from your heater is pretty common, but it is because of corrosion in the water pipes or the tank itself. It is because of the sacrificial anode in it, which rusts.

This problem is one that you should call a technician for, so they can check the sacrificial anode and replace it for you.

#4. The Water Heater Shut Off.

You sometimes notice your heater only produces hot water sometimes. For example, it can be during a shower or when doing the dishes; you get hot water, then it switches to cold water.

This problem can be because of the distance between the heater and the faucet. It can also be that you’ve exhausted the water heater flow rate causing the hot water to stop.

It can also result from a faulty flow sensor or a tripped circuit breaker. 

You can fix it by running the water until it produces hot water. To avoid exhausting the flow rate, use only a few hot water faucets simultaneously.

Check if the circuit breaker tripped or if you need to replace it. You can call a technician for this and also help with the faulty flow sensor.

The key to enjoying your Rheem water heater when it malfunctions is to know how to troubleshoot it. Then, you know if you can fix it and get it up and running in no time.

Why Trust Our Information

At Homeguideinfo.com, we are dedicated to delivering precise and trustworthy information. Our content is meticulously developed and validated by a panel of Expert Contributors, adhering to strict Editorial Guidelines. Our commitment is to ensure that you receive thoroughly researched and expertly crafted information.