How to Flush an Electric Tankless Water Heater

Understanding Tankless Water Heaters

Electric tankless water heaters are modern, energy-efficient devices that provide hot water on demand without the need for a storage tank. Unlike traditional water heaters, they heat water instantaneously as it flows through the unit. This eliminates standby heat loss and reduces energy consumption.

Why Flush an Electric Tankless Water Heater?

Flushing an electric tankless water heater is essential for maintaining its efficiency and longevity. Over time, mineral deposits, sediment, and scale can accumulate inside the heating elements and pipes, leading to reduced water flow, decreased performance, and potential damage.

Benefits of Flushing:

Improved water flow and pressure
Increased energy efficiency
Reduced risk of overheating and damage
Extended lifespan of the water heater

Frequency of Flushing

The frequency of flushing depends on the hardness of your water. In general, it is recommended to flush your electric tankless water heater every 6-12 months in areas with moderate to hard water. For very hard water, flushing every 3-6 months is recommended.

Materials Needed:

Bucket
Garden hose
Utility brush (optional)
Vinegar or descaling solution
Screwdriver or wrench (optional)

Step-by-Step Guide:

1. Shut Off Power and Water Supply:

Locate and turn off the circuit breaker or disconnect switch that supplies power to the water heater.
Close the cold water inlet valve to the water heater.

2. Drain the Water Heater:

Attach the garden hose to the drain valve at the bottom of the water heater.
Place the other end of the hose in a bucket and open the drain valve to drain the water from the unit.

3. Remove the Inlet Filter:

Locate the cold water inlet on the water heater.
Unscrew the filter screen using a screwdriver or wrench, if applicable.
Clean the filter screen with a utility brush and rinse it under running water.

4. Apply Vinegar/Descaling Solution:

Mix 1 gallon of white vinegar or a descaling solution with 1 gallon of water in a bucket.
Pour the solution into the cold water inlet where the filter screen was located.
Leave it to sit for 30-60 minutes.

5. Flush with Water:

Reattach the garden hose to the drain valve.
Open the cold water inlet valve and the drain valve to flush the vinegar/descaling solution through the water heater.
Continue flushing until the water runs clear.

6. Reassemble the Inlet Filter:

Insert the cleaned filter screen back into the cold water inlet.
Screw it back into place.

7. Restore Power and Water Supply:

Turn on the circuit breaker or disconnect switch to restore power to the water heater.
Open the cold water inlet valve to refill the water heater.
Check for leaks around the inlet valve and drain valve.

Additional Tips:

Use a commercial descaling solution specifically designed for electric tankless water heaters for a more effective flush.
If the water flow is significantly restricted or the water heater is overheating, it may indicate a more serious problem that requires professional attention.
Regular flushing will help prevent buildup and extend the lifespan of your electric tankless water heater.
Consider installing a water softener if your water is particularly hard.
If you are unable to flush the water heater yourself, contact a licensed plumber for assistance.