Rheem Tankless Water Heater Maintenance

Rheem Tankless Water Heater Maintenance

This is a complete guide on Rheem tankless water heater maintenance. In this guide, I will describe: 

  • Rheem tankless water heater maintenance schedule or how often you should maintain the water heater.
  • The step-by-step procedure to service the water heater.
  • And the safety guidelines you must follow when maintaining the water heater.

So, let’s get started right here. 

Table of Contents

Rheem Tankless Water Heater Maintenance Schedule

Here maintenance schedule means how often you should maintain your Rheem Tankless Water Heater. Some parts of your water heater should be inspected regularly, while other components need to be checked periodically or annually.

For example, you need to inspect the condensate drain line daily to make sure the condensate is draining properly. The air filter of the water heater also demands regular inspection. 

On the other hand, you should drain your tankless water heater every month to drain sediment buildups. 

And lastly, it’s recommended to check the water heater burner, venting system, water filter, pressure relief valve, and air intake filter annually. 

If you follow this water heater maintenance routine, your water heater will offer you years of trouble-free service. 

Rheem Tankless Water Heater Maintenance: The Step-by-Step Procedure

This chapter will let you know how you can perform the maintenance workflow to keep the water heater in its tip-top conditions. Here what I am going to break down in this section: 

  • Cleaning the Outer Area of the Unit 
  • Air Filter Cleaning 
  • Water Filter Cleaning
  • Draining The Water Heater 
  • Venting System Inspection
  • Burner Inspection
  • Flushing The Water Heater

Safety Tips: Before performing any maintenance or servicing workflow, you must turn off the water heater and disconnect the electric supply to the heater. 

01. Cleaning The Outer Area Of The Unit

Let’s start from the beginning! Clean around the water heater by removing dirt, debris, and lint using a vacuum cleaner. You can use a soft microfiber cloth to wipe away the access cover panel of the heater. Don’t forget to clean the remote control as well. Just use a soft damp cloth and gently wipe it. Then, leave the water heater surfaces to dry. 

02. Air Filter Cleaning

Cleaning the air filter on a Rheem Tankless Water Heater is simple. Just take the air filter out from the top of the water heater. Then, wash the air filter with water. You can use mild detergent and a soft brush to wipe away dirt and debris. Once you rinse the air filter, leave it in the air to let the filter dry. Then, reinstall the air filter once the air filter gets dried. 

03. Water Filter Cleaning

Water Filter On Rheem Tankless Heater
*Water Filter On Rheem Tankless Heater*

Follow the below steps to clean the  water filter of your Rheem Tankless Water Heater: 

Firstly, ensure you turn the unit off and disconnect electric power from your water heater. 

Secondly, you should turn off the water supply to your water heater. In this case, set the cold water shut-off valve to the off position. 

Thirdly, drain your water heater. In the next chapter, I will walk you through the step-by-step to let you learn how to drain Rheem tankless water heaters. 

Once you drain all the water, it’s time to remove the water filter. Just pull out the water filter by unscrewing it from the base of the cold water inlet line and slide the filter out of the line carefully. 

Now, bring the water filter to your sink and wash it with water. You can use a soft brush to remove sediment buildups. 

Afterward, put the water filter back into its place and tighten it up until it fits snugly. Avoid over-tightening the water filter. Otherwise, it will damage the water filter or deform it. 

Finally, end the water filter cleaning workflow by setting the cold water shut-off valve to the open position. Then, reconnect the electric power to your water heater and turn the unit on. 

04. Draining the Water Heater

It’s simple to drain water from the tankless water heater. Follow the below steps to drain water: 

  • Turn off the heater by pressing the on/off switch.
  • Set the gas shut-off valve to the close position. 
  • Disconnect the electric power to your unit at the circuit breaker box. 
  • Now, turn on all the hot water faucets in your home to run the water until cold water is coming. Then, turn off the faucets.
  • Turn off the cold water shut-off valve.
  • Pull out the water filter from the base of the cold water inlet line. Make sure you position a plastic bucket right underneath the inlet to collect water. 
  • Attach a garden hose to the drain valve in the hot water outlet line and set the other end of the hose to the nearest floor drain. Let the garden hose connect until all the water is draining out. 
  • Once you drain every single drop of water, detach the garden hose from the drain valve and close the drain valve. 
  • Put the water filter back into its place and open the cold water shut-off valve. 
  • Turn the power supply on at the circuit breaker.
  • Finally, turn on the gas shut-off valve and end with turning on your water heater. 

05. Venting System Inspection

You should inspect the venting system annually. Ensure all the vent sections and the vent connections are secure and airtight. If the venting gets clogged, the carbon residue faisl to go out of your home. I recommend you hire a certified plumber to check the venting system if you are not easy to do that. The following video will come in handy regarding this: 

06. Burner Inspection

Burner Inspection
*Burner Inspection*

Like the venting system, it’s recommended to inspect the water heater burner annually. To check the burner: 

First, use a screwdriver to remove 6 screws that hold the access panel cover in its place. Then, pull the access panel cover. 

Second, turn on a hot water faucet. 

Third, inspect the burner light through the burner sight glass while operating the water heater. If you notice unusual burner operation or the flame is not blue, it’s time to repair or replace the burner assembly. I highly recommend you hire a professional to do this task for you. 

Lastly, put the access panel cover back into its place. 

07. Flushing The Water Heater

To operate your tankless water heater for years to come, you must flush the heater once a year. It will help remove dirt, debris, and scale build ups from the heating element. Ensure you have the following Rheem tankless water heater flush kit: 

  • Distilled vinegar
  • A plastic bucket
  • A couple of hoses
  • A submersible pump

Once you have these accessories at your fingertips, check out this article on Will vinegar damage a hot water heater. I don’t only provide an answer to this question in that article but also describe how to flush a tankless water heater with vinegar. 

Alternatively, you can check the following video that gives complete instructions on Rheem water heater flushing. 

Safety Tips You Must Follow While Performing Maintenance Workflow

Dealing with a tankless water heater means playing with hot water or electricity. If you make a mistake, it will burn your skin or cause an electric shock. So, follow the safety guideline below to avoid unwanted hazards or serious injuries.  

  • Turn the water heater off and disconnect it from electric power. No matter what servicing workflow you are about to perform, you must maintain this safety tip. 
  • Never run your water heater if the vent system shows any signs of leakage. It would lead you to death or personal injury. 
  • Be careful when inspecting the burner because it requires you to remove the front cover panel, which exposes you to live electricity. 
  • Never keep combustible materials like clothing, flammable liquids, or even cleaning ingredients next to or around the water heater. Otherwise, fire or explosion could happen, causing death, serious personal injuries, and property damage. 
  • Hot water will come out when you operate the pressure relief valve manually. So, keep people and children from the unit. 
  • Never allow children to run or handle the water heater.


Do tankless water heaters require annual maintenance?

Yes, you should maintain your tankless water heater annually. Almost every area in the USA or Canada or other countries has ‘hard’ and ‘very hard’ water, which forms scales on the heating element. So, you must flush the tankless water heater every year to descale the water heater. Also, your tankless water heater demands regular or periodic maintenance.

Does Rheem tankless water heater have a filter?

Yes, Rheem tankless water heaters have a filter named water filter. It is located right above the cold water inlet valve (it’s the blue handle).

How much does it cost to descale a tankless water heater?

It will cost at least $150 to descale or flush a tankless water heater. On the other hand, the cost will be reduced if you descale the unit yourself. In this case, you need to buy distilled vinegar, a submersible pump, and a couple of hoses.

How long should I run vinegar through my tankless water heater?

You should run vinegar through the tankless water heater for at least an hour to break down scale and sediments and flush them out of the water heater.

What happens if you don't flush your water heater?

If you don’t flush your water heater, it will corrode the heating element of your water heater. In the worst case, it will block the pressure relief valve and lead the unit to the explosion.


Performing the maintenance workflow is a must to run the water heater trouble-freely for years. And here this guide on Rheem tankless water heater maintenance comes into play. 

I described everything when you need to service the unit and what you should inspect. So, follow this guide and maintain your water heater accordingly. Best of luck!

Read Also:

Rheem Tankless Water Heater Troubleshooting Manual

Rheem Tankless Water Heater Code 12

Similar Posts

One Comment

  1. Thank you for writing this article. I just bought our 1st tankless wh, a Rheem 36w. As this has it’s own water filter, is it still recommended to put in a sediment or whole house filter (we have well water)? I’ve read a number of blogs suggesting a separate water filter is a good idea for tankless water heaters. Then there’s the suggestion to use a water conditioner, ie a descaling unit. We haven’t had our unit installed yet, but want to be completely prepared to give it the longest life. Your maintenance schedule is so great to have. Thanks again!

Leave a Reply

Your email address will not be published. Required fields are marked *