1- Turn off the power source for your tankless water heater. 2- Close and turn off the 3 water valves attached to your tankless water heater. 3- Remove the purge port valve caps slowly from the purge valves located on each of the cold and hot water valves. 4- Attach your hosing lines to each of the 3 valves. 5- Open the purge port valves by twisting them perpendicularly to the position of the cold and hot valves.
6- Use 2.5 gallons (9.46 liters) of undiluted white vinegar to clean
your tankless water heater at all times instead of chemical solutions.
7- Perform the flushing and draining procedure by following the
directions provided by the manufacturer of your tankless water heater. 8- Close the purge port valves by twisting the "T"-shaped handles after the flushing process has been completed. 9- Disconnect and remove the hosing lines from each water valve. 10- Replace the purge port valve caps onto the purge valves.
11- Refer to the manufacturer's manual of your tankless water heater
for exact instructions on how to safely re-start your water heater. 12- Turn on the hot water tap in your sink slowly to allow the air to pass through the pipe.