Rheem Instant Hot Water Heater Problems – Causes and Solutions

If you have chosen the comfort and convenience of a Rheem tankless water heater, you are probably used to having access to hot water whenever you desire. However, just like any other appliance, it is possible that you will eventually run into some problems with your Rheem Instant Hot Water Heater.

Rheem instant hot water heater problems

To make things easy for you, we have provided this straightforward guide to common problems that can occur with Rheem water heaters. Not only will we identify the various causes of these common water heater issues, but we will also provide troubleshooting tips and solutions so you can get your heater working the way it should as quickly as possible.

Why is My Rheem Water Heater Not Heating – Common Causes

To make things easy, we have broken down the most common issues Rheem hot water heater owners run into. Identifying the problem is always the first step in fixing your hot water heater, so compare your own issues with those listed below.

Complete Lack of Hot Water

If your Rheem hot water heater is not producing any hot water at all, there could be a number of explanations for this issue.

If you are running an electric model, the first thing you will want to do is check the electrical box for your home and make sure you have not tripped a circuit breaker. While a Rheem hot water heater is relatively efficient, it still requires a significant amount of power, especially if you are placing heavy demands on it. In many cases, just checking the electrical box is enough to address the issue.

If you have one of the larger gas-powered models, it is possible that the gas valve could have been accidentally shut off. If your particular Rheem heater operates with a pilot light, you should also consult your instruction manual and make sure it is lit properly.

Water Temperature is Too Low

If you are finding that your Rheem water heater cannot produce hot water for long enough, or the water temperature is too low, it is possible that it is not powerful enough for your needs. In other words, your hot water requirements could be exceeding your Rheem hot water heater’s water heating capabilities.

If this is the case, the best thing to do is to try and limit how much hot water you use over a short period of time. Run tests to check on the water temperature and see if the water heater can keep up.

If you find this helps, the problem could be as simple as your water heater not being powerful enough for your needs. Essentially, you have two choices: Either upgrade your water heater to a more powerful unit, or reduce the amount of hot water you use.

Low temperature water in faucet

If you cannot afford a larger unit, or you do not have space for one, you can make small adjustments, like taking shorter showers, installing low-flow faucet adaptors and shower heads, and washing your clothes with cold water.

If reducing your hot water usage has done nothing to correct the low water temperature, it might be worth checking the heating elements to make sure that they are operating correctly.

It is also possible that the internal thermostat could be malfunctioning, which could mean it needs to be serviced or replaced. Luckily, both the heating elements and the thermostat are relatively easy to replace, so it is worth reaching out to Rheem if you suspect that these components could be causing your water heater problems.

It is also possible that mineral deposits could be building up within the unit, which can even become an issue with a tankless unit, as the pipes and valves leading away from the unit can become clogged.

How Do I Reset My Rheem Tankless Water Heater?

If you are encountering error codes and you suspect that they could be the cause for your Rheem water heater’s problems, you can also try resetting the internal computer. Resetting the entire system will not necessarily fix your problem, but it is worth trying if you have tried everything else.

The following is a step-by-step guide to resetting a Rheem tankless water heater:

  • Close all taps and shut off your water hater’s intake valve
  • Press and hold the red reset button on the back of your water heater. On some of the newer models, there is a reset button located on the remote control, which will also work
  • Wait at least five minutes, which should be enough time for your Rheem tankless water heater to fully reset
  • Turn the water heater back on using the remote or front control panel
  • Re-open the water intake and then test a faucet to see if your water heater is producing hot water

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How Do You Troubleshoot a Rheem Tankless Water Heater?

As mentioned above, the first thing you should do is check your electrical box to make sure that your water heater has not tripped a circuit. Once you are sure that the problem is not a power issue, you can move onto the next troubleshooting steps.

Rheem tankless water heater circuit diagram

The most common problems and maintenance concerns you will encounter with your Rheem tankless water heater include the following:

  • Mineral Buildup – You need to keep an eye out for mineral buildup inside your water heater, as hard water contains a high mineral content, which can clog up the interior of your water heater. Check the interior of the unit for the presence of calcium, magnesium, and limescale buildup. You can often address this issue by installing a new water filter, which will collect the mineral deposits, so they do not have the opportunity to block the path to your unit’s heat exchanger. You can also run a simple descaling cleaning solution through the unit to remove the buildup.
  • System Overload – You could be using too much hot water and overloading your hot water heater. As discussed, you can test this by using less water and checking if it makes a difference. Either replace the water heater with a larger unit, or reduce your daily hot water usage.
  • Exhaust Blockage – Your hot water heater needs to vent pressure and air from the combustion chamber. If your water heater’s venting and exhaust system is blocked, it could be causing the entire water heater to malfunction. Check the exterior vent to make sure debris has not clogged the vent.
  • Check the Error Code Guideline – Rheem water heaters can display a variety of error codes. If you are getting an error code, consult the instruction manual, or Rheem’s website. If you cannot find the same code by consulting an error code guideline, you should contact Rheem or a licensed technician.

Final Words

Luckily, it is fairly unlikely that you will encounter any serious Rheem instant hot water heater problems. However, in the event that you do come across any problems, perform the checks outlined above and you should be able to address the problem. If that fails, consider reaching out to Rheem’s customer service line, as they will be happy to walk you through any problems you might be experiencing.

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