Inspected the on-demand water heater. Isolated and drained some water from the heater. Removed and cleaned the cold water strainer. Reconnected and opened valves. Turned the system on and had the customer turn the hot water on. The unit starts and runs properly. The unit is approximately 8 yrs old and nearing the end of life. Duct Diagnostic- 203-734-1532. Aeroseal