Compare the flow and temperature at the pressure relief valve.
o If the temperature and flow rate are correct at the PRV then the problem resides in the plumbing line, not in the tankless unit. Check for a cross connection or other water line problems
Test the hot water temperature with a handheld thermometer to measure how far off the water temperature is from the set temperature.
o The set temperature may be set too low. The temperature can be changed with the
pushbuttons on the PCB or by the remote temperature controller, if one is installed.
Check for cross plumbing between cold water lines and hot water lines. See the Procedures section (p. 21) for instructions.
Unit may be hard water scaled. The scale acts as an insulator preventing the heat exchanger from transferring heat to the water. Contact a Takagi Service Agent.
The unit may not be receiving enough gas.
o The gas supply valve may not be fully open.
o The gas line may be sized improperly.
o The gas supply pressure may be too low. This may be caused by a malfunctioning gas supply regulator, so check to see if your regulator is working properly.
Check to see that a check valve is installed between the pump discharge and the connection to the cold water supply. Inspect the check valve for proper operation. If there isn’t one installed, or if it is malfunctioning, cold water may be back?feeding into the system.
Double?check for a 101 error code. A 101 error code will reduce the amount of gas input into
Output temperature will be affected if air flow is impeded.
o Check construction dust and debris in venting, such as dry wall.
o If there is dust inside the cabinet, there will also be dust inside the burner and heat exchanger. See the procedure for cleaning the burner (p. 26).