How do you properly flush a Rinnai tankless water heater?

To properly flush a Rinnai tankless water heater, you should first turn off the power and water supply to the unit. Next, connect a pump and hoses to the service valves on the unit to circulate a descaling solution through the system. Let the solution sit for the recommended time, then flush it out by running clean water through the unit. Finally, disconnect the hoses and restore power and water supply to the unit.