Situation description: Back to back installation of 2 banks of 4 each natural gas fired, 240,000 btu tankless water heaters to create a potable hot water supply for a hotel. The heaters circulate water into two 500 gallon water storage tanks. The water heaters are on a "Cascade" network and run the majority of time, but not 100% of the time. The operating temp is 146 degrees F.

This last week two water heaters, side by side on the same bank developed gas leaks. It turns out when the flexible CSS gas connectors were being replaced it was observed that the "flare" portion of the SS gas connector seems to have largely disappeared. I have several images of this on my phone and computer but I have not seen a way to upload the images to the board. (Images are not posted online).

The flare fittings are steel, and the flare on the CSS is apparently SS. I attempted to call the manufacturer "Dormont" customer service on Friday but they were closed for inventory. These tankless heaters were installed in March of 2022. So 20 months of service to catastrophic failure. These were installed by professionals and the job was inspected. I'm curious if anyone else has observed a similar type failure? And if anyone has an idea how these failed. I find it hard to believe that Dormont would send out gas connectors with too small flares on their connectors. The two heaters being side x side seems more than coincidental. Could this be vibrationally related?


Images: [postimg.cc]



Edited 1 times.

Posting pictures - [www.plbg.com]

Have you removed any of the other connectors, to check the flares?

Yep. I unscrewed the S5 which is the unit next to the the two failed units. S6 & S7. So the S5 flare appeared to be smaller than a new CSS gas connector flare, but definitely larger than the two failed flares. S5 was not leaking gas.

The images can (hopefully) be seen on this link. [postimg.cc]

soooooo

either dress the flare(s) to proper spec [reflare them using a flaring tool]

or

replace the connector(s)

or

hire in a licensed bonded insured piping professional

==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

i'd wait and talk to someone at dormont.
they should have a manufactures rep in the area to look things over.
we're talking serious stuff here.
no one except dormont should take responsibility for possible defective parts.
i would also get the gas inspector involved.
you have changed or altered gas piping. get a permit and have an inspection.
they may want that area isolated and pressure tested ?

OK. So I failed to mention that I've been a licensed plumber / gasfitter since 1984. So I'm qualified to work on this, I also helped to install this tankless system. Although I didn't design it, or initially connect the flexible CSS gas connectors.

I won't tamper with or alter a CSS gas connector factory connection. I'm pretty sure my insurance wouldn't cover my company if things go badly.

I plan to contact Dormont again Monday morning. Hopefully "inventory" will have concluded and customer service can get involved.

Primarily I was hoping maybe someone else had previously seen this phenomena and had an idea of what the failure's root cause might be. If it happened here it's most likely happened elsewhere.



Edited 1 times.

sounds like a good plan.
please post back as things progress.
good luck.

Interesting... I assume that the part was manufactured correctly and was not leaking when installed. It looks from the pics like the flare was collapsed. Like the mating surface on the male side was not the correct angle, and the fitting nut was over tightened to the point where it started to draw the flare. I'm not a plumber but hope that these didn't leave factory like this. But if they did....they would have leaked from day #1, correct? Maybe they started to leak and the handyman tightened the bejeezus out of it trying to get it to reseal, then gave up and called you?