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Hello All, Im new to this forum and have a question -

Can anyone comment why is there black soot (or black specks) that could be coming from coming hot water line? Client lives in Chicago area, Eternal Tankless waterheater model GU145S installed December 28 2010 (2.3 years ago).

Background --> Client really likes the unit because it eliminates the cold sandwhich, and it allowed them to install in their air conditioned 4 foot tall crawl space, which could not have been done with a conventional tank based water heater. The Eternal unit actually has a small built-in tank but is under the size limit so it can be ranked as a tankless. However, over time client claims that it produced bursts of "black soot" that stick to the side of the sink and shower making a black dirty ring that must be scrubbed to get off. They say it has become more prevelant over the years since original installation. Under normal useage they rarely see the black soot, but in the instance where they turn on the hot water valve quickly to almost full flow (such as bathtub faucet), a blast of black particles come bursting out (also claim to hear a thud). Upon cycling the water on/off the soot goes away. The problem doesnt happen again for a couple of days, the longer you wait to perform the cycle test, the more black particles will come out when the hot line is cycled.

Unit Failed two days ago --> the Eternal unit failed and was leaking (pouring) large volumes of water. Heavy water sprayed internally to the unit, soaking the electronics board. I noticed the electronic board had some corrosion and rust on some of the resistor or jumper components - which would lead me to believe that this leaking problem was intermittently coming and going possibly causing condensation and corrosion inside the unit. I suspect that the failure was either the heat exchanger or the valve o-ring went bad (manufacturer will not allow further breakdown of the unit). The "HOT WATER TUBE ASSEMBLY", white valve to the right of assy was spraying out the back near the seal. Upon contacting Grand Hall (manufacturer of the Eternal tankless waterheater) regarding the black particles - they would always change the subject, never refering to it, asking about the oringinal installation. Now that the unit failed, they are warranty replacing it with a new unit. However, there is still no acknowledgement of the black particles.

Suspecting FAILED O-RING is cause of black particles --> I read a blog somewhere that made reference to o-ring discintigrating causing black particles. Maybe its possible that the temperature rise from the winter time in chicago caused such extreme conditions that the "HOT WATER TUBE ASSEMBLY" or "HEAT EXCHANGER" was not designed for. According to other installer sources, there are more failures for this Eternal tankless unit in the midwest (IL, MN, MI, IN) region of USA, and very few failures CA, TX, FL, AZ. Sources also say that the newer units have an improvement in the design of the valve that reduces the problem of failure for this device.

Can anyone confirm this problem, and where they think the black soot, black specks, or black particles in the hot water are coming from?

(by the way - Original installer "Imperial Tankless of Mundelien" went out of business the month after this client had the unit installed).
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