Faced with a $400 maintenance bill for a 10-year-old tankless water heater, one homeowner asked the internet whether it made more sense to pay for another flush or put that money toward replacing the unit.

Here's what to know

In Reddit's r/Plumbing community, the homeowner explained that the system was bought in 2016 and had been flushed just twice before, in 2018 and 2023. 

While trying to decide on the next step, the poster asked the forum, "Would you flush a tankless water heater that is 10 years old with the last flush being three years ago? Or better to wait and replace entire system at end of life?"

The homeowner said two plumbers they consulted with gave opposing recommendations. One advised proceeding with the flush, while the other said tankless systems tend to last only 10 to 12 years anyway and that the money would be better saved for a replacement.

Several commenters challenged that claim of a shorter lifespan. One commenter who said they were a plumber wrote, "I can't remember ever replacing one that wasn't broken by winter weather that was less than 16 years old."

Another commenter added, "If you are on unsoftened or unfiltered water they should be flushed yearly, if not more," and said DIY kits can be much cheaper than paying for service. 

Overall, the replies suggested that the decision depends on things like local water hardness, the manufacturer's recommended service intervals, and the warranty on the heat exchanger. Commenters also noted that if a professional flush feels too expensive, a DIY flush kit and descaling solution can reduce the cost of keeping up with maintenance.

The thread never reached a full consensus. One plumber said that holding off could be reasonable if the homeowner was not prepared to replace the unit immediately in the event of a failure, while others said a flush still has value because it helps maintain performance, supports warranty-related maintenance, and could expose a problem before it turns into a flood.

For anyone who does choose replacement, Cala offers a different path than simply swapping in another conventional model. Cala's customizable smart heat pump water heaters help homeowners decrease their energy bills by heating water exactly when it's needed. 

That means less wasted energy, better alignment with daily hot-water use, and a more strategic upgrade for people already spending money on a failing system. Homeowners weighing long-term operating costs may want to compare standard replacements with Cala.

Where can I learn more?

If you're deciding whether to keep maintaining an older water heater or start planning for a replacement, these stories break down the same tradeoffs.

• A homeowner with a corroded 10-year-old unit found tankless units especially tempting during replacement planning.

• For people ready to replace, heat pump water heaters can cut operating costs over time.

• Homeowners comparing long-term bills found tankless systems can save through better energy efficiency.

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