Navien Tankless Water Heater – Quarterly Preventative Maintenance

Required PPE: Safety gloves, eye protection

Turn off power to the Navien unit at the breaker.

Shut off cold and hot water isolation valves.

Close gas supply valve to the unit.

Relieve pressure by opening the hot water tap at a nearby sink.

Inspection & Cleaning

Refer to the instructional videos below for step-by-step guidance on performing the Navien tankless water heater flush and descaling procedure. These resources should be reviewed before beginning the task to ensure proper execution and safety.

1) Serial Number

Remove front cover and add picture of Serial No. tag inside for each serviced unit.

Add or drag pictures

2) Serial Number

Remove front cover and add picture of Serial No. tag inside for each serviced unit. N/A if only one unit is present.

Add or drag pictures

Refer to the instructional videos below for step-by-step guidance on performing the Navien tankless water heater flush and descaling procedure. These resources should be reviewed before beginning the task to ensure proper execution and safety.

Clean air intake filter with compressed air or wash with mild soap and water.

Clean inlet water filter screen.

Remove, rinse, and inspect condensate trap for debris or obstructions.

Inspect for leaks and connections

Fittings
Valves
Gaskets

Flush & Descale Heat Exchanger

Attach hoses to the service ports on both hot and cold lines.

Fill a 5-gallon bucket with 2 gallons of water along with one tub of granular descaling solution or 4 gallons white vinegar.

Insert pump into the bucket and connect to the cold-water service port.

Place the hot return hose back into the same bucket.

Open both service valves.

Run the pump and circulate the solution through the system

Navien-approved descaler (e.g., Flow-Aide, Rectorseal Calci-Free) 30–45 minutes
White vinegar (5–6% acetic acid) 60–90 minutes

Shut off the pump, close service ports, and drain solution from the hoses.

Dispose of used solution in accordance with local regulations.

Fresh Water Rinse

Refill the bucket with fresh clean water.

Run pump again for 5–10 minutes to flush residual solution.

Disconnect hoses and close service ports.

Open hot and cold isolation valves to restore normal water flow.

Power On & Verify Operation

Recordkeeping

Log date of service.

Technician name.

Type of descaling solution used

Navien-approved descaling solution
Food-grade white vinegar

Preparation

Required PPE: Safety gloves, eye protection

Turn off power to the Navien unit at the breaker.

Shut off cold and hot water isolation valves.

Close gas supply valve to the unit.

Relieve pressure by opening the hot water tap at a nearby sink.

Inspection & Cleaning

Refer to the instructional videos below for step-by-step guidance on performing the Navien tankless water heater flush and descaling procedure. These resources should be reviewed before beginning the task to ensure proper execution and safety.

1) Serial Number

Remove front cover and add picture of Serial No. tag inside for each serviced unit.

2) Serial Number

Remove front cover and add picture of Serial No. tag inside for each serviced unit. N/A if only one unit is present.

Refer to the instructional videos below for step-by-step guidance on performing the Navien tankless water heater flush and descaling procedure. These resources should be reviewed before beginning the task to ensure proper execution and safety.

Clean air intake filter with compressed air or wash with mild soap and water.

Clean inlet water filter screen.

Remove, rinse, and inspect condensate trap for debris or obstructions.

Inspect for leaks and connections

Fittings

Valves

Gaskets

Flush & Descale Heat Exchanger

Attach hoses to the service ports on both hot and cold lines.

Fill a 5-gallon bucket with 2 gallons of water along with one tub of granular descaling solution or 4 gallons white vinegar.

Insert pump into the bucket and connect to the cold-water service port.

Place the hot return hose back into the same bucket.

Open both service valves.

Run the pump and circulate the solution through the system

Navien-approved descaler (e.g., Flow-Aide, Rectorseal Calci-Free) 30–45 minutes

White vinegar (5–6% acetic acid) 60–90 minutes

Shut off the pump, close service ports, and drain solution from the hoses.

Dispose of used solution in accordance with local regulations.

Fresh Water Rinse

Refill the bucket with fresh clean water.

Run pump again for 5–10 minutes to flush residual solution.

Disconnect hoses and close service ports.

Open hot and cold isolation valves to restore normal water flow.

Power On & Verify Operation

Turn on water and gas supplies.

Restore power to the unit.

Check for any error codes.

Run hot water tap and verify unit fires correctly and maintains consistent temperature.

Recordkeeping

Log date of service.

Technician name.

Type of descaling solution used

Navien-approved descaling solution

Food-grade white vinegar

Notes on inspection (filters, heat exchanger, trap, etc.).

Any abnormalities found or repairs recommended.