A.O. Smith Signature 100 40-Gallon Short 4500-Watt Double Element Electric Water Heater - Item #816158 | Model #E6-40R45DV

• Ideal hot water delivery for households with 2-3 people when sized appropriately

• Two 4,500-watt copper heating elements provide a first hour delivery of 55 gallons

• Save money and energy with this energy efficient model that operates at a 0.92 Uniform Energy Factor (UEF)

• Short 49.75-in H x 20.5-in diameter design is ideal for condensed spaces like under a staircase or a closet installation

• Premium heating elements, anode rod and fused ceramic tank shield provide superior tank protection and extend water heater life

• Non-CFC polyurethane foam insulation and factory-installed heat trap nipples reduce heat loss for maximum efficiency and energy savings

• Easy temperature control with adjustable thermostat can be set higher for dishwashers and laundry machines or lower as needed

• Factory-installed temperature and pressure relief valve and tamper-proof drain valve ensures safe operation
  

Specifications

What our Experts Think

• Reliable hot water for small households: The 40-gallon capacity with dual 4500-watt heating elements delivers a first-hour rating of about 55 gallons, making it well-suited for homes with 2–3 people and typical daily hot-water needs.

• Efficient electric performance: With a 0.92 Uniform Energy Factor (UEF), this unit helps lower energy consumption while maintaining consistent hot water supply for showers, laundry, and dishwashing.

• Space-saving short design: The short 49.75-inch height and 20.5-inch diameter allow installation in tighter spaces such as utility closets, basements, or under staircases where taller tanks may not fit.

• Durable tank protection: Built with premium heating elements, a protective anode rod, and a fused ceramic tank shield to help reduce corrosion and extend the life of the tank.

• Improved insulation for energy savings: Non-CFC polyurethane foam insulation and factory-installed heat trap nipples reduce heat loss, helping the system maintain water temperature more efficiently.

• Easy temperature adjustment: An adjustable thermostat lets homeowners fine-tune water temperature based on household needs, from everyday showers to higher-temperature appliance use.

• Built-in safety features: Includes a factory-installed temperature and pressure relief valve and tamper-resistant drain valve to support safe and reliable operation.

• Dependable warranty coverage: Backed by a 6-year limited tan

Q&A

Q: What household size is this 40-gallon water heater best for?
A: This model is ideal for households of 2–3 people, providing consistent hot water for showers, laundry, and daily household use.

Q: How powerful are the heating elements?
A: It features two 4,500-watt copper heating elements, designed to heat water quickly and deliver a first-hour hot water rating of about 55 gallons.

Q: Is this electric water heater energy efficient?
A: Yes. The system operates at approximately 0.92 Uniform Energy Factor (UEF), helping reduce energy usage and operating costs compared with less efficient models.

Q: What makes the “short” design beneficial?
A: The short 49.75-inch height and 20.5-inch diameter make it ideal for installation in tight spaces such as closets, basements, or under staircases.

Q: Does this water heater include safety features?
A: Yes. It includes a factory-installed temperature and pressure relief valve, adjustable thermostat, and tamper-resistant drain valve to support safe operation.

Q: What protects the tank from corrosion and damage?
A: The heater uses a fused ceramic tank shield, protective anode rod, and premium heating elements to help extend tank life and reduce corrosion.

Q: What are the electrical and installation requirements?
A: The unit operates on 240 volts, uses top water connections, and is designed for indoor residential installation

Maintenance Tips

• Flush the tank annually: Drain and flush the tank every 6–12 months to remove sediment buildup that can reduce heating efficiency and damage heating elements.

• Inspect the anode rod: Check the sacrificial anode rod after the first 6 months and then yearly; replace it if heavily worn to prevent tank corrosion.

• Check heating elements and thermostat: Periodically inspect the upper and lower 4500-W heating elements and thermostats to ensure consistent hot water and proper operation.

• Look for leaks and corrosion: Inspect the tank base, fittings, and pipes regularly for rust, moisture, or leaks to avoid costly damage.

• Test the T&P relief valve: Operate the temperature & pressure relief valve yearly to ensure it opens and closes properly, preventing dangerous pressure buildup.

• Always fill the tank before powering on: Ensure the tank is completely full of water before turning on electricity to avoid dry-firing and burning out heating elements.

• Keep the area clean: Maintain a dry, well-ventilated space around the heater for safe operation and easier servicing.