A.O Smith 40-Gallon Tall Natural Gas Water Heater (18" Diameter) - Item # 12231959 | Model # GCB-40 SIDE T&P VALVE

A.O Smith 40-Gallon Tall Natural Gas Water Heater (18" Diameter) - Item # 12231959 | Model # GCB-40 SIDE T&P VALVE

• 40 Gal
• Tall
• 18" Dia x 61.75" Height To Vent Connection
• Top Water Connections And Side T&P Valve
• Not Available In Specific AQMDs In CA
• DynaClean Diffuser System Reduces Sediment Buildup, Extending Tank Life
• Blue Diamond Tank Lining Provides Protection Against Leaks
• Enhanced Honeywell Gas Valve With LED Diagnostics To Ease Troubleshooting And Improve Performance
• Resettable FVIR Thermal Switch To Quickly And Easily Bring Heater Back Online
• CoreGuard Anode Rod Is Industry-Leading Anode Technology To Extend Useful Life
• Full-Flow Tamper-Resistant Brass Drain Valve
• Meets 2015 NAECA Efficiency Standards
• 0.65 Uniform Energy Factor
• 40,000 Btu
• Mfg #GCB-40 (SIDE T&P VALVE
• Water heater blanket included
• 18" Dia x 61.75" Height To Vent Connection
• Top Water Connections And Side T&P Valve

What our Experts Think

• Solid everyday performance: A classic 40‑gallon tall natural gas water heater with 40,000 BTU input and atmospheric venting delivers consistent hot water for a household of ~3 people (first‑hour ratings near ~78 gal).

• Corrosion‑resistant tank: Blue Diamond® glass lining protects the steel tank from rust, helping extend service life and reduce leaks compared with standard glass coatings.

• Sediment control for longevity: The DynaClean diffuser system helps reduce lime and sediment buildup, extending heater life and maintaining output over time.

• Diagnostics & ease of use: Enhanced Honeywell gas valve with LED status indicators makes troubleshooting and temperature control easier for homeowners and technicians.

• Durable components included: CoreGuard anode rod, full‑flow tamper‑resistant brass drain valve, and resettable FVIR thermal switch provide robust protection and long‑lasting reliability.

• Side‑mounted safety relief: Side T&P valve placement gives flexible installation options and meets standard residential safety requirements.

Q&A

Q: What household size is this water heater suitable for?
A: Ideal for households of 2–3 people, providing reliable hot water for showers, sinks, and daily use.

Q: What type of fuel does it use?
A: Operates on natural gas, delivering efficient and consistent heating.

Q: What are the dimensions of this tall water heater?
A: 40-gallon capacity with an 18-inch diameter, designed for vertical installation in utility spaces or closets.

Q: How powerful is the heater?
A: Provides fast recovery with standard BTU output for consistent hot water.

Q: Does it include safety features?
A: Yes. Comes with a temperature and pressure (T&P) relief valve for safe operation.

Q: Is it energy efficient?
A: Yes. Engineered for reliable performance with minimal energy waste.

Q: How is the tank protected from corrosion?
A: Equipped with a protective anode rod and premium tank materials for long-lasting durability.

Q: What are the installation requirements?
A: Requires natural gas connection, proper venting, and indoor residential installation

Maintenance Tips

• Flush the tank annually: Drain and flush every 6–12 months to remove sediment and maintain heating efficiency.

• Inspect the anode rod: Check the sacrificial anode rod yearly and replace if heavily corroded to prevent tank rust.

• Check gas and vent connections: Ensure gas lines, fittings, and venting are secure, unobstructed, and corrosion-free.

• Test the T&P relief valve: Operate the temperature & pressure relief valve yearly to ensure proper function and safety.

• Monitor burner operation: Watch for irregular ignition or flame changes, which may indicate venting or gas issues.

• Inspect for leaks: Regularly check water connections, fittings, and tank base for moisture or corrosion.

• Maintain proper airflow and space: Keep the surrounding area clean, dry, and well-ventilated for safe operation and easy maintenance.