Q&A for How to Maintain a Tankless Water Heater

Return to Full Article

Coming soon

Add New Question

Question

What do I do if there is water leaking and steam comes out when the hot water is in use?

Community Answer

Your heat exchanger has cracked and needs to be replaced. You can buy just that part, or replace the whole tankless heater. Replacing just the part is less expensive (for parts), but I replaced the whole unit because the water had leaked onto the electronics, and who knows when that would cause another failure.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 2 Helpful 8
Question

Do I need to do this even if I have a water softener?

Community Answer

Yes, as it's important to properly maintain a tankless water heater. The heating elements get extremely hot and bake calcium and other deposits on the heating units quickly. Filtering even clean municipal water should be done. Neglecting to maintain a tankless heater results in a very short life span. They're a very sensitive piece of machinery and require you to maintain them. Install a filter before the heater and clean them twice a year for a long lifespan. It is required. You're cleaning baked on junk off the heating element more so than dirt or debris.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 9 Helpful 18
Question

After flushing a Rinnai tankless water heater with white vinegar, can I store and reuse the vinegar next time?

Community Answer

No, the used vinegar has dissolved solids in it and is no longer "virgin." Discard the used vinegar and always use fresh vinegar for flushing.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 5 Helpful 18
Question

Can I use cider vinegar instead of white vinegar?

Community Answer

No. You can switch them out when cooking, but the cider vinegar has added coloring which is not good for your heater. It may leave stains, while white vinegar will not.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 5 Helpful 11
Question

What will make it not heat water?

Community Answer

Check the temperature fuses (thermostats) on each heating unit. Check for continuity through them using a multimeter.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 5 Helpful 8
Question

Could using CLR damage my tankless water heater?

Community Answer

Yes, using CLR or similar chemical cleaning solutions can be harmful to your tankless water heater and potentially impact your health, as they could contaminate your drinking and bathing water. It's recommended to use 2.5 gallons (9.46 liters) of undiluted white vinegar for cleaning instead.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 3 Helpful 8
Question

Why won't my Rheem tankless heater turn on when I open the basement faucets, despite cleaning the filters and flushing the unit?

Community Answer

Your basement faucets may have a flow rate that's too low to activate the heater. This can be due to water-saving fixtures, clogged filters, line restrictions, or partially closed valves. Check the flow rate by timing how long it takes to fill a one-gallon pail and compare it to the heater's minimum flow specifications.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 0 Helpful 4
Question

We have very hard water here. Can I let the virgin white vinegar circulate for 2 - 3 hours without harm?

Community Answer

Yes, but it’s not needed for that long. Try one hour, then another hour with fresh vinegar the next day.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 2 Helpful 7
Question

I live in a rental apartment. The hot water stops after about few minutes of use and needs to be turned off for a minute or two in order to get hot again. The super has no clue. What should I do?

Community Answer

There could be many problems. First, how is water heated? What type of device is used? There can be something like safety problem (temperature could be so high, so it needs some kind of stop and "restart"). You'll have to call the super.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 1 Helpful 2
Question

Can using Calcium, Lime & Rust Remover (CLR) damage my tankless water heater?

Community Answer

Yes, using CLR can damage the metal components of your tankless water heater, and it's not safe for your bath water.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 2 Helpful 5
Question

How often does this need to be done?

Community Answer

Usually annually to stay within warranty. If you have hard water, you may need to do it bi-annually. Check with the manufacturer to be certain.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 0 Helpful 1
Question

How will I know when I am done with the de-calcification process?

Community Answer

It should be about 30-45 minutes, but this depends on your method of cleaning (e.g., a larger pump will flush faster). The accompanying manual should tell you how long to flush.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 0 Helpful 2