How to Descale a Rheem Tankless Water Heater

A tankless water heater is a great way to save energy and enjoy hot water on demand. However, like any appliance, it needs regular maintenance to keep it running smoothly and efficiently. One of the most important tasks you can do for your tankless water heater is descaling it.

Descaling is the process of removing the mineral deposits and scale that build up inside the heat exchanger of your tankless water heater over time. These deposits can reduce the water flow, lower the efficiency, and damage the components of your unit.

In this blog post, we will show you how to descale a Rheem tankless water heater step by step.

 Tools and materials

• A bucket
• A submersible pump
• Two hoses
• A pair of pliers
• A pair of gloves
• A bottle of white vinegar or a commercial descaling solution
• A towel

Step 1: Disconnect the supply and power

The first step is to disconnect the water supply and power to your tankless water heater. You can do this by turning off the main water valve and unplugging the unit from the outlet or switching off the circuit breaker. This will ensure your safety and prevent any damage to the unit.

Step 2: Release pressure and attach the hose

The next step is to release the pressure inside the unit and attach the hose to the service valves. You can do this by opening a hot water faucet in your house and letting it run until the water stops flowing. Then, close the faucet and locate the service valves on your tankless water heater. They are usually located at the bottom of the unit and have red and blue handles.

You will need to turn both valves perpendicular to the pipes to close them. Then, use a plier to unscrew the caps on the valves and attach one end of each hose to them. Make sure the hoses are long enough to reach a bucket.

Step 3: Pour the vinegar solution into the bucket

The third step is to pour about four gallons of white vinegar or a commercial descaling solution into a bucket. You can use either one, but vinegar is cheaper and more eco-friendly. Then, place the bucket near your tankless water heater and submerge the pump into it. Connect another end of one hose to the outlet of the pump and leave the other hose loose.

Step 4: Let the solution circulate through the heat exchanger for an hour

The fourth step is to let the vinegar solution circulate through the heat exchanger for an hour. You can do this by plugging in or turning on the pump and opening valve A (the blue one) on your tankless water heater. This will allow the solution to flow from the bucket into the cold water inlet of your unit.

Then, open valve B (the red one) on your tankless water heater. This will allow the solution to flow out from the hot water outlet of your unit back into the bucket.

You should see bubbles forming in the bucket as the solution dissolves the scale inside your heat exchanger. Let this process run for about an hour or until you see no more bubbles in the bucket.

Step 5: Dump the dirty solution and pour in some fresh water

The fifth step is to dump the dirty solution and pour in some fresh water into the bucket. You can do this by unplugging or turning off the pump and closing both valves on your tankless water heater. Then, disconnect both hoses from your unit and drain them into another bucket or a sink.

Next, dump out the dirty solution from your first bucket and rinse it well. Then, fill it with fresh water and submerge your pump into it again. Connect one end of each hose to your pump and service valves as before.

Step 6: Detach the hose and close service valves

The final step is to detach both hoses from your unit and close both service valves. You can do this by plugging in or turning on your pump again and opening both valves on your tankless water heater. This will allow fresh water to flush out any remaining vinegar solution from your heat exchanger.

Let this process run for about 10 minutes or until you see clear water coming out from both hoses. Then, unplug or turn off your pump and close both valves on your tankless water heater. Disconnect both hoses from your unit and drain them into another bucket or a sink. Replace the caps on the service valves and tighten them with a plier.

Step 7: Restore the supply and power

The last step is to restore the water supply and power to your tankless water heater. You can do this by turning on the main water valve and plugging in the unit to the outlet or switching on the circuit breaker. Then, open a hot water faucet in your house and let it run for a few minutes to purge any air from the system.

Congratulations! You have successfully descaled your Rheem tankless water heater. You should notice an improvement in the water flow, temperature, and efficiency of your unit. You should repeat this process at least once a year or more often depending on the hardness of your water and the frequency of use.