I have a Navien 210a water heater on gas. It is 5 years old , no problems. It has internal recirculation turned on . No external features.I would hear the recirculation pump and burner kick on in the mornings before my shower, about 20 minutes before but I dont really hear that anymore. so not 100% sure if that is working. there are no error codes.
I have the same brown/greasy sticky stuff all over the black parts inside the cabinet! What on earth is this from? Why is it only on the black parts? I have a CO detector in the main floor and this unit is in the basement but no alarms.
There is also some corrosion on some of the pipes. The little red cap also was a bit loose and there was clear water around it. Really weird things.
i have maintanied this unit yearly with vinegar flushes. I ph0ned Navien and they just said to phone a service tech.
I also looked into the condensate pump which pump the condensate fluid to the laundry drain. I tested it and it is working, but when i looked inside there is the clear condensate liquid, watery but also there is a collection of brownish residue floating around that looks about the same color as the greasy sticky stuff inside the tankless cabinet. So i am pretty sure there is condensate that is collecting on the plastic parts. How? I don't know.
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