AO Smith Commercial Electric Tank Water Heaters DEN-80

Warning: This procedure requires trained personnel with PPE!

Is the water heater showing signs of lime scale accumulation?

If no signs of lime scale accumulation, skip to step 7

Describe the signs of lime scale accumulation

Upload a photo of the lime scale accumulation

Proceed with the lime scale removal process

Is UN-LIME® Professional Delimer available?

If UN-LIME® Professional Delimer is not available, contact Technical Support for assistance in ordering

Follow the instructions on the UN-LIME® to delime the water heater

Turn off the electrical supply to the water heater

Ensure the cold water inlet valve is open

Open a nearby hot water faucet and let the water run until the water is no longer hot

Close the cold water inlet valve to the water heater

Connect a hose to the water heater drain valve and terminate it to an adequate drain

Open the water heater drain valve and allow all the water to drain from the storage tank

Close the water heater drain valve when all water in the storage tank has drained

Close the hot water faucet opened in Step 3

If the water heater is going to be shut down for an extended period, the drain valve should be left open

Turn off the electrical supply to the water heater

Ensure the cold water inlet valve is open

Open a nearby hot water faucet and let the water run until the water is no longer hot. Then close the hot water faucet

Connect a hose to the drain valve and terminate it to an adequate drain

Ensure the drain hose is secured before and during the entire flushing procedure. Flushing is performed with system water pressure applied to the water heater

Open the water heater drain valve to flush the storage tank

Flush the water heater storage tank to remove sediment and allow the water to flow until it runs clean

Close the water heater drain valve when flushing is completed

CAUTION! Property Damage Hazard

Inspection and replacement of anode rod required.

The anode rod is used to protect the tank from corrosion.

Anode deterioration depends on water conductivity, not necessarily water condition.

Artificially softened water is exceedingly corrosive.

The anode rod should be inspected annually.

The following are typical (but not all) signs of a depleted anode rod:

The majority of the rods diameter is less than 3/8”.

Warning: Ensure no one is in front of or around the outlet of the Temperature-Pressure Relief Valve discharge line during the check. The water discharge may be extremely hot.

Temperature-Pressure Relief Valve in operating condition

Valve seats properly and operates freely after lifting the lever several times

Does the valve continue to release water after manual operation?

If the valve continues to release water, close the cold water inlet to the water heater and drain the water heater. Replace the Temperature-Pressure Relief Valve.

Does the Temperature-Pressure Relief Valve weep or discharge periodically?

Note: Excessive water pressure is the most common cause of Temperature-Pressure Relief Valve leakage. If leakage is due to pressure build up in a closed system without a thermal expansion tank, it is not covered under the limited warranty.

Sign off on the Temperature-Pressure Relief Valve check