The water that passes through your tankless unit carries minerals like calcium. When water is heated, partially dissolved sediments are left behind. These minerals can collect within the inside components of the tankless water heater — primarily the heat exchanger — and can cause the unit to run inefficiently and, over time, even overheat.
Descaling is the process of removing those minerals.
What’s needed for a descaling
- Descaling kit (pump, container, hoses)
- Descaling / isolation valves at the unit
- Shut-off valve at the unit
- White vinegar or descaling agent
Steps
- Turn off the water and gas valves into the tankless unit.
- Turn off the cold and hot water valves.
- Remove the caps from the descaling / isolation valves.
- Connect one hose end to the pump and the other end to the cold-side descaling / isolation valve.
- Connect the second hose end to the hot-side descaling / isolation valve and place the open end into the bucket.
- Fill a quarter of the bucket with white vinegar or descaling agent.
- Make sure the descaling / isolation valves are in the open position and plug in the pump.
- Run the descaling process for 30–45 minutes.
- When complete, disconnect the pump, close the descaling / isolation valves, and remove the hoses.
- Turn the main water valve and gas valve back to the open position.
After the process is complete, flush 10–15 gallons of water through the unit to ensure the descaling agent is fully removed.