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I've read many negative comments of early Navien products. Apparently the original products fall into two areas; either faulty parts or poor installation and unfamiliarity by plumbers and diyers with troubleshooting.

My understanding is tankless water heaters are standard in Europe and Asia so this may make tankless products a new learning curve in America. Fortunately my choice seems to be an exception to negative reviews as my installation occurred two months ago and now using heat for its first winter. A licensed plumber trained in Naviens transformed a standard hot water boiler for a 3-zone hydronic system and dhw heater into one tankless unit with all new plumbing already cutting my monthly gas bill in NYC. Heating is perfect and silent.

Hot water is perfect although there is a delay but acceptable once old habits change (instead of turning on full hot water to the tub then switching to shower, the shower is used to reduce water flow while allowing heating to occur in less than a minute). My old boiler ran out of hot water all the time when filling the washer but now fills with hot water. My guess is original Naviens were problematic with early teething pains, discontinued and then reintroduced to the market with upgrades. If I'm not mistaken, mine is the top of the line product and seems to be trouble free, meeting its specifications.

Having a licensed plumber familiar with Naviens to make a brand new installation incorporating all the external plumbing parts for correct installation may be another key to a successful changeover from tank to tankless. My cost is not inexpensive but a quick calculation of savings on gas usage shows a break even point as early as 8-yrs provided nothing breaks.

Reason of review: Good quality.

I liked: Professional installation with attention to detail.

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From what I've read/experienced, you are in the honeymoon phase. The Navien shows it's true colors, aka defectiveness, after about a year or two. Maybe you'll be the exception to the rule, good luck.

to Amy morgan #1582995

Yes, I'm aware of non issues early in the life of some Naviens with many having problems later on. Hopefully I won't become another negative statistic.

I flushed the heat exchanger on dhw and boiler side with zero issues. In the year of operation, I've see much lower gas bills and anticipate the same as the second heating season comes around. being new to tankless, I searched online for relative pros and cons of Naviens and other brand name tankless units. WIth tankless unfamiliarity mostly in the USA market, there are a few tankless owners with more than ten years of dependable use with every one of satisfied long term owners never going back to tanked heaters.

Most if not all of Europe, the middle East, Asia, New zealand and Australia using tankless heaters. Like anything else, each type has their issues with youtube showing diyers and plumbers pointing out issues. Some are wear and tear with simple parts replacement, diyers learning from mistakes attempting self repairs, and major repairs with heat exchangers failing, Big ticket items like heat exchangers are either under warranty with labor charges borne by the homeowner. Most brands I find use copper heat exchangers and failed ones show leaking from worn copper units.

Navien uses stainless upper and lower heat exchangers and a third stainless heat exchanger for heating dhw. I believe Navien may be one of the very few to use stainless for longer reliability. Since mineral deposits vary from region to region, some may have serious issues with blocked passages while others have zero issues. Living in NYC, my water is considered soft with very little mineral content so flushing yearly may not be necessary.

I learned as much as I can to be as informed as possible. I liken tankless heaters no different from cars, trucks and suvs when electronic fuel injection systems and emissions controls replaced older systems. Electronic sophistication in vehicles scares many diyers with some repair shops unwilling to stay abreast of EFI systems. The same with licensed plumbers unwilling to stay abreast of higher efficiency tankless heaters with electronics.

Those not willing to learn about electronics in tankless units are doomed to second guessing. Those attending manufacturers seminars to learn how tankless requires additional knowledge to knock off the rust from plumbers forgetting basics are reminded of many things needed to make an installation as trouble free as possible to minimize or eliminate call backs. I've found plumbers with many tankless installations reporting little to zero complaints after installations, leaving me with the impression that knowledge on the part of the installer is a key to proper installation and a happy homeowner.

I've done my research and hope I'm in the small but growing homeowners group happy to switch to tankless. It's not for everyone and educated plumbers will know what works and doesn't.


thanks for the review is all still going well?

to patricia #1501638

Yes, mine is still going strong without issues. I'm due a flush routine later this year before heating season to ensure descaling minimizes build up.

I corresponded with Navien and they acknowledged homeowners/diyers can perform the descaling without voiding warranty. I've searched and found many problems related to scale build up, mainly in other countries with similar results when descaling solves buildup preventing water flow thru heat exchangers. Some homeowners suffered complete blockage of their heat exchangers, requiring replacement.

Being aware of issues unique to on demand boilers may allow diy participation in preventative measures. The same procedures used by plumbers can be accomplished by homeowners and I'm preparing for servicing my unit later in the year.


Let's just hope that your assumptions regarding quality improvement are correct. I had a top-of-the-line combination unit installed in 2011.

Hot water baseboard heating plus unlimited, on-demand domestic hot water. My gas bill went down, and everything worked beautifully for the first 3 years. Then, problems began. Every year it would stop working during the heating season.

Repair would take anywhere from 1-2 days up to 2 weeks! Parts had to be shipped from California and didn't come promptly. "Expert" Navien trained techs had the utmost difficulty trouble shooting the unit. Despite my having soft water, the unit MUST be descaled annually.

It seems the act of descaling inevitably would cause an O-ring to break, wreaking havoc on the circuit board. Obviously a poor design allowing this inevitably leakage (O-rings do not last forever) to destroy expensive circuitry. Repairs were always in the hundreds of dollars.

In the meantime we would shiver and be unable to bathe or shower. In fact, my unit is down right now.

to not ready for prime time #1453001

Does your unit use upper and lower stainless heat exchangers? This seems to be the solution to corrosion issues.

Scaling is another issue that needs to be done depending on local water quality, low mineral content or not. My understanding of scale issues is the small area of heat exchanger that's prone to scaling from high heating temperatures.

Descaling is a necessary evil no different from oil burners needing yearly maintenance to keep them in tune for best performance. I'm not averse to performing descaling as I already have a pump and just need a set of hoses for hook up.

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