Madison Co. Virginia | rockridgefarms - 7/12/2024 06:37
call navian tech support, while standing in front of your unit, they should walk you threw the steps
They refused, because I said I was the owner and not a plumber. I'll try again and claim to be a plumber, and see if it makes a difference.
There's four thermistors in the water line. Thermistor A in the cold supply --> flow sensor --> flow control valve --> secondary heat exchanger(for condensing the exhaust) --> Thermistor B --> primary heat exchanger --> Thermistor C --> Thermistor D in the hot water output.
C and D read the same as each other, since I'm not cascading this unit with other units, and the mixing valve that dumps cold water into the line between these two thermistors isn't coming into play here at all. A reads accurately. But B is all over the place. It frequently alternates between a reasonable temperature(somewhere between A and C like it should), and a temperature that's even lower than A.
I swapped A and B thermistors, and the problem stayed with B, according the digital display of sensor temperatures. It's still not throwing any codes related to this.
Is there any possibility that a scaled heat exchanger could cause it to cycle that thermistor every two seconds between a good reading and an erroneously low reading, or cause the burner and fan to cycle between high and low every five seconds?
My next step is to get a spare thermistor to swap in, and also double-check propane pressures with a manometer. I'll see if I can scrounge up enough stuff to flush the unit with a descale acid flush. Beyond that, I'm kind of at a loss. |
Troubleshooting Navien tankless water heater?
