Tankless Water Heater Maintenance

Once you’ve made the decision to install a tankless water heater you’ll want to learn how to maintain it properly to increase its performance and to lengthen its life. With regular and proper water heater maintenance it is very possible to enjoy 15-20 years of service from your tankless heater. There are 3 basic maintenance procedures that will help you get the most from your heater. The first is to check the  water heater maintenancewiring for signs of wear. The second water heater maintenance step is to clean the filter periodically. The third step is to flush the system regularly to remove deposits from the boiler.

VERY IMPORTANT: Before you do ANY water heater maintenance, turn off the electrical circuit the water heater uses. Lock out the circuit if possible.

How to Check the Wiring for Wear

WITH THE POWER TO THE UNIT OFF, open the cover of the water heater and carefully check all wiring. Gently rotate it to make sure you can see all sides of it, since the spots most likely to suffer wear may be turned away from the cover. If signs of wire wear are present, and especially if bare wire is showing, call a plumbing professional immediately and do not use the unit until it is repaired.

How to Clean the Tankless Water Heater Screen

Turn off the main water valve or shut off the pump. WITH THE POWER TO THE WATER HEATER OFF, unscrew the water supply to the bottom of the tankless heater. You’ll find either a flat or cone-shaped filter inside, depending on the brand of heater. Carefully flush the screen under running water. This can be done by placing a bucket in a utility sink and holding the screen under the running water and over or in the bucket. Or you can pour water from a gallon jug over and through the filter as you hold it over a bucket. The key is to do it so that the screen can’t be lost (down the drain, for example) if it should slip out of your hand. How often you perform this water heater maintenance step depends on the quality of your water. Do it for the first time after 3-6 months to check for sediment in the filter. This will help you gauge how often it must be done.

Tankless Water Heater Maintenance How To Flush The Tank

Since this water heater maintenance procedure takes multiple steps, we’ll number them for convenience.

1. Gather your supplies: A utility pump (may be rented); 3 garden hoses or washing machine hoses – the pump may come equipped with its own hose; 2 gallons of white vinegar; 2 large buckets; pipe wrench.

2. Remember to proceed only WITH THE POWER TO THE WATER HEATER OFF.

3. Close the cold and hot water valves by rotating them until the handles are perpendicular to their valve body.

4. Open the drain caps very slowly on each purge port. Check them to make sure the rubber washers remain in the caps. Allow all water to drain out.

5. Attach one hose to the cold water inlet on one end and to the outlet side of the pump on the other end.

6. The second hose should attach on one end to the inlet side of the pump and with the other end resting in the first bucket.

7. Attach the third hose to the hot water outlet and let it drain into the second bucket.

8. Pour 2 gallons of white vinegar into the first bucket. Plug in the pump and turn it on. It will suck vinegar in and send it via the cold water inlet into the water heater. It will circulate through the heater and drain into the second bucket.

9. When the bucket of fresh vinegar is empty turn off the pump and switch buckets and repeat the process, or simply put both loose hose ends into the bucket with the vinegar and turn on the pump. The vinegar coming out of the heater should become cloudy as it dissolves lime and calcium.

10. Let vinegar circulate through the water heater for 20 minutes and with vinegar in the heater turn off the pump and quickly close both valves, isolating vinegar within the water heater. Let it sit for 20 minutes. Open both valves again, turn on the pump and let it circulate for another 20 minutes.

The flush is now complete. Remove the hoses, reattach the cold water supply and the hot water outlet line. Turn the water back on as well as the power. Open a nearby hot water tap very slowly until it is about ¼ open. Let the air bleed out of the water line and heater. Let the hot water run for 1-2 minutes after it stops sputtering. The white vinegar is harmless and will not damage the environment. It is safe to pour directly down the drain.

This water heater maintenance should be done on a yearly basis at least. If you know your water has high sediment content you may want to do it every 6 months. A little bit of water heater maintenance will go a long way toward enhancing the longevity of your tankless water heater and giving you continued outstanding performance.

Be sure to watch this great video on how to Flush your tankless water heater.

Outside Resources:
Rheem Cleaning kit

Do you have any suggestions or tips on cleaning your tankless water heater? Please share it with us below.

Remember water heater maintenance will extend the life of your system.

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2 Responses to “Tankless Water Heater Maintenance”
  1. Fantastic information. As a new Navien NR-210A owner, this information will be extremely helpful throughout the years. I’m preparing to deploy to Afghanistan (again) and I’ve printed, linked, sent by carrier pigeon… this information and video’s to my wife. I’ll prep everything so when she’s ready, all she has to do is hit “Play”, “Pause”, Execute, … rinse/repeat. Thanks Dave! GREAT SITE! GREAT INFO!

    • Dave says:

      First off thank you for your service. Our prayers are with and your family. I think that with some effort and a little patience and help from folks like you tankless water heaters will become the norm in this country much like they are in Europe. Proper maintenance is a very important factor in keeping a healthy hot water system.

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