We own a Takagi T-KD20 and the heater worked fine for over ten years but recently it's had an issue staying on when demanding for hot water and the pressure drops over time. At the moment we can't get the heater to kick on AT ALL. (Cold water flows just great though) we've cleaned the water fliter and still nothing. We've drained the pressure tank and made sure everything was set right and made sure the well pump was set correct. We have had black soot also come up (through the pump i believe) so i dont know if that would clog the heater. Haha we have tried everything, but can't seem to get the heater to even initiate anymore so if anyone has any ideas on what it could be I would appreciate the help. Thanks...oh and no error codes either so if that narrows it down.