A.O. Smith Signature Series 6.6-GPM 160000-BTU Indoor Natural Gas Tankless Water Heater - GT15-240-NI

• Enjoy continuous hot water for up to 2 simultaneous showers and 3 sink when sized appropriately (sink and shower calculations are based on a 0.5 GPM faucet and a 2.5 GPM showerhead in the southern zone)

• Save money and energy with our ENERGY STAR® qualified Ultra-Low NOx indoor model that operates at a 0.94 Uniform Energy Factor (UEF)

• Compact, indoor wall-mounted design frees up valuable storage space

• Uses 1/2 inch gas line up to 10 feet or 3/4 inch gas line for longer lengths

• Easy temperature adjustment and troubleshooting with integrated controls

• Copper primary heat exchanger and stainless steel secondary heat exchanger provide superior heat transfer and protection resulting in extended product life

• Worry free safety features include freeze, overheat, and surge protection as well as troubleshooting diagnostic codes
  

What our Experts Think

• Trusted Multi‑Stage Filtration – The A.O. Smith 2‑Stage Carbon Block Under Sink Water Filtration System (AO‑US‑200) uses two Claryum® carbon block filters to reduce up to 99 % of 78 harmful contaminants including lead, PFAS, chlorine, mercury and pharmaceuticals, while preserving healthy minerals.

• Certified Quality You Can Rely On – Fully WQA certified to NSF/ANSI standards 42, 53 and 401, ensuring the system’s filtration performance and structural quality meet recognized safety benchmarks.

• Dedicated Brushed Nickel Faucet Included – Comes with a 100 % lead‑free, brushed nickel faucet that delivers filtered water on demand without altering your existing kitchen faucet.

• Cost‑Effective and Eco‑Friendly – Filters last up to 6 months or 500 gallons, with no wastewater during operation — making this system efficient and more sustainable than bottled water.

• DIY‑Friendly Setup – Installation is designed to be straightforward with all necessary parts included, often requiring no plumber in standard under‑sink setups.

• Noticeably Better Water Taste – Many users report improved taste and smell from filtered water compared to unfiltered tap water, ideal for drinking, cooking, coffee, and tea.

• Practical Flow for Everyday Use – Delivers water at a steady ~0.5 GPM, suited to kitchens serving 1–4 people, though some find the flow slower than a regular faucet.

• Mixed Long‑Term Feedback – While many owners value the water quality and ease of installation, some report issues with leaks or fitting challenges if not installed carefully.

Q&A

Q1: What is the A.O. Smith G6‑T4035NVR?
A: The A.O. Smith Signature 100 G6‑T4035NVR is a 40‑gallon commercial/residential natural gas water heater built for reliable hot water delivery in homes sized for 3–4 people.

Q2: How much heating power does it provide?
A: It features a 35,500 BTU low‑NOx natural gas burner that delivers efficient hot water and meets emissions standards.

Q3: What capacity and performance can I expect?
A: The tank has a 40‑gallon nominal capacity (≈38 gal rated) and can produce an estimated ≈65 gallons in the first hour of use when sized appropriately.

Q4: What warranty does this model include?
A: It comes with a 6‑year limited warranty on tank and parts plus a 1‑year limited labor warranty for peace of mind.

Q5: What safety and diagnostic features does it have?
A: Features include a self‑diagnostic electronic gas control with LED status indicator and a built‑in safety system to reduce accidental flammable vapor ignition.

Q6: Is it easy to install in tight spaces?
A: Yes — its tall, slim 61.75″ H × 20″ diameter profile makes it suitable for narrow installations like closets or utility rooms.

Q7: How durable is the unit?
A: A protective anode rod and fused ceramic tank shield help reduce corrosion and extend water heater life.

Q8: Can it be used at high elevations?
A: This model is high‑altitude certified up to about 10,100 ft, making it versatile for many locations.

Maintenance Tips

• Flush the Tank Annually: Drain and flush the storage tank at least once per year to remove sediment buildup that reduces efficiency and lifespan.

• Inspect Anode Rod: Check the sacrificial anode rod after the first 6 months and then annually; replace when heavily corroded to prevent internal tank corrosion.

• Test T&P Relief Valve: Lift the temperature & pressure relief (T&P) valve once a year to ensure proper pressure relief and safety.

• Check for Leaks & Corrosion: Periodically inspect around water connections, drain valve, fittings, and vent piping for leaks or corrosion; address promptly.

• Clean Exterior & Vent: Wipe the exterior to keep it free of dust; verify proper venting and clear obstructions to maintain combustion efficiency and safe exhaust.

• Monitor Temperature Setting: Keep thermostat at recommended ~120 °F to balance comfort, energy savings, and reduce scaling.