A. O. Smith DRE-120-100 Commercial Electric Water Heater Instruction Manual

Introduction and Safety Information

This manual provides essential instructions for the installation, operation, and maintenance of your A. O. Smith DRE-120-100 Commercial Electric Tank Type Water Heater. Please read all instructions carefully before installation and use. Retain this manual for future reference.

Safety is paramount. Installation and service of this water heater must be performed by qualified personnel only. Failure to follow these instructions can result in property damage, personal injury, or death.

Observe all local codes and ordinances. Ensure proper grounding and electrical connections. Do not operate the water heater if any part has been submerged in water.

Image: Front view of the A. O. Smith DRE-120-100 Commercial Electric Water Heater. This image shows the cylindrical tank design, typical for commercial electric water heaters, with a gray finish. The control panel and plumbing connections are visible on the upper portion of the unit.

Setup and Installation

Proper installation is critical for safe and efficient operation. This unit is designed for indoor installation only.

Location Requirements:

Install in a clean, dry area, protected from freezing temperatures.
Ensure adequate clearance for servicing and maintenance.
Locate near a floor drain or provide a suitable drain pan with a drain line to prevent water damage in case of leaks.

Plumbing Connections:

Connect cold water inlet and hot water outlet pipes.
Install a temperature and pressure (T&P) relief valve in the designated opening. Route the discharge pipe from the T&P valve to an open drain.
Fill the water heater completely with water before applying power. Open a hot water faucet to allow air to escape during filling.
Check all connections for leaks after filling.

Electrical Connections:

Ensure the electrical supply matches the voltage requirements of the water heater (208 Volts).
Connect the water heater to a dedicated, properly sized circuit breaker.
Follow all national and local electrical codes.
This unit features phase convertible wiring. Consult the wiring diagram inside the access panel for specific instructions on converting between single and three-phase power, if applicable.

Operating Instructions

Once installed and filled with water, the water heater is ready for operation.

Initial Startup:

Ensure the water heater is completely filled with water and all air has been purged from the system.
Turn on the electrical power supply to the water heater at the circuit breaker.
The heating elements will begin to heat the water. This process may take several hours for the initial heating cycle, depending on the water volume and desired temperature.

Temperature Adjustment:

The DRE-120-100 features surface-mounted thermostats. Access to these thermostats is typically behind an access panel.
Adjust the thermostat(s) to the desired water temperature. A common setting for commercial applications is 120°F (49°C) to 140°F (60°C), but local codes and specific application needs may vary.
Caution: Hot water can cause severe burns. Exercise extreme care when setting water temperature.

Maintenance

Regular maintenance ensures optimal performance and extends the life of your water heater. All maintenance should be performed by qualified service personnel.

Annual Maintenance:

Drain and Flush Tank: To remove sediment buildup, drain a few gallons of water from the tank via the drain valve. For heavy sediment, completely drain and flush the tank.
Inspect Anode Rod: The anode rod protects the tank from corrosion. Inspect it annually and replace if significantly depleted.
Test T&P Relief Valve: Manually operate the T&P relief valve by lifting the lever. Water should discharge from the drain pipe. If no water discharges, or if the valve does not reseat properly, replace it immediately.
Inspect Heating Elements: Check for scale buildup on heating elements. Descale or replace as necessary.
Check Electrical Connections: Verify all electrical connections are tight and free from corrosion.

Note: Water quality can significantly impact maintenance frequency. In areas with hard water, more frequent draining and anode rod inspection may be required.

Troubleshooting

Before calling for service, review the following common issues and their potential solutions. Always disconnect power to the unit before performing any inspection or repair.

Problem	Possible Cause	Solution
No hot water or insufficient hot water	No power to unit Thermostat set too low Tripped high-limit switch Faulty heating element(s)	Check circuit breaker. Adjust thermostat setting. Reset high-limit switch (located near thermostat). Test and replace faulty element(s).
Water leaking from tank	Loose plumbing connection Faulty T&P relief valve Corroded tank (rare)	Tighten connections. Replace T&P relief valve. Contact qualified service personnel for tank inspection.
Noisy operation (rumbling, popping)	Sediment buildup in tank Loose heating element	Drain and flush tank. Tighten heating element.

Specifications

Key technical specifications for the A. O. Smith DRE-120-100 Commercial Electric Water Heater:

Model Number: DRE-120-100
Capacity: 119 Gallons (Nominal 120 Gallons)
Power Source: Corded Electric
Voltage: 208 Volts
Wattage (Input): 6 KW
Heating Elements: Goldenrod 24K Elements Standard, Individual Element Fusing
Thermostats: Surface Mounted
Phase: Phase Convertible
Installation: Indoor Installation
Color: Gray
Manufacturer: AO Smith
UPC: 671657059798
ASIN: B07GZ76SZW

Warranty Information

A. O. Smith water heaters are backed by a manufacturer's warranty. Specific warranty terms and conditions, including duration and coverage, are provided with the product at the time of purchase. Please refer to the separate warranty document included with your water heater for complete details. Retain your proof of purchase for warranty claims.

Customer Support

For technical assistance, parts, or service inquiries, please contact A. O. Smith customer support. Have your model number (DRE-120-100) and serial number ready when you call.

You can find contact information on the A. O. Smith official website or within the warranty documentation provided with your unit.

A. O. Smith Official Website: www.aosmith.com

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