A.O. Smith Signature Series 8-GPM 190000-BTU Indoor Natural Gas/Liquid Propane Tankless Water Heater - Item #1055556 | Model #GT15-310C-I
A. O. Smith's Signature Series Non-Condensing Ultra-Low NOx Indoor Tankless Gas Water Heater uses up to 190,000 BTU/h of natural gas or propane to deliver a 8 gallons per minute flow rate (based on a 35°F rise) of continuous hot water for your home when sized appropriately. This makes it a good match for whole home applications. A. O. Smith Tankless Gas water heaters only heat water when needed, making them one of the most energy efficient ways to heat water. This high efficiency non-condensing indoor model has a 0.82 Uniform Energy Factor (UEF) and can reduce your energy consumption and save money on your energy bills. Additionally, our Tankless Gas design can be easily wall-mounted indoors, saving you valuable storage space. This model may qualify for additional energy efficiency rebates and tax credits in your local area. See Lowe's Rebate Center for details. Not sure if this is the right water heater for you? Use our product selector tool to see if this model is the right fit for your hot water needs. Tankless gas water heaters have special installation requirements. Professional installation is required.
Features
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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)
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Save money and energy with our energy efficient Ultra Low NOx indoor model that operates at a 0.82 Uniform Energy Factor (UEF)
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Compact, indoor wall-mounted design frees up valuable storage space
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Uses 3/4 inch gas line and is easily convertible from natural gas to propane with supplied kit
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Easy temperature adjustment and troubleshooting with integrated controls
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Primary heat exchanger design provides superior heat transfer and protection resulting in extended product life
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Worry-free safety features include freeze, overheat, and surge protection as well as troubleshooting diagnostic codes
What our Experts Think
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Continuous whole‑home hot water: Delivers up to 8 GPM of on‑demand hot water, enough for 2 simultaneous showers plus sinks when sized correctly—ideal for medium households.
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Energy‑smart and low emissions: Rated Ultra‑Low NOx with a 0.81 Uniform Energy Factor (UEF) for efficient gas use and lower operating costs compared to standard tank systems.
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Space‑saving indoor design: Wall‑mounted and compact, this indoor tankless heater frees up floor space and integrates easily into utility rooms.
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Fuel flexibility: Comes with a kit to convert between natural gas and liquid propane, giving homeowners installation choice based on fuel availability.
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Durable heat exchanger: Commercial‑grade heat exchanger enhances heat transfer and extends unit life, backed by a 15‑year limited warranty on the heat exchanger.
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Safety and control features: Built‑in freeze, overheat, surge protection and diagnostic codes support safer operation and easier troubleshooting.
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Professional install required: To maximize performance and meet local codes, expert installation is recommended.
Q&A
Q: What type of fuel does this tankless water heater use?
A: It operates on natural gas or liquid propane, offering flexibility depending on your home’s fuel source. (aosmithatlowes.com
Q: What is the flow rate and capacity?
A: Delivers up to 8 gallons per minute (GPM), supporting simultaneous hot water use for showers, sinks, and appliances. (aosmithatlowes.com
Q: What are the benefits of a tankless design?
A: Provides continuous hot water on demand, saves space, and reduces energy costs compared to traditional storage water heaters. (aosmithatlowes.com
Q: What safety features does it include?
A: Features built-in flame failure protection, freeze protection, and overheat shutoff, ensuring reliable and safe operation. (aosmithatlowes.com
Q: Can it be installed indoors?
A: Yes. This model is designed for indoor residential installation with proper venting for natural gas or propane. (aosmithatlowes.com
Q: Is it energy efficient?
A: Yes. Tankless technology heats water on demand, avoiding standby heat loss and lowering monthly energy bills. (aosmithatlowes.com
Maintenance Tips
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Descale the unit annually: Flush the heat exchanger with a vinegar or descaling solution every 12 months to remove mineral buildup, especially in hard water areas.
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Clean the inlet water filter: Inspect and rinse the cold water inlet screen filter regularly to prevent flow restrictions.
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Check venting and gas connections: Ensure vent pipes, gas lines, and fittings are secure, free of obstructions, and corrosion-free.
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Monitor ignition and flame operation: Watch for irregular burner ignition or flame color changes, which can indicate blockages or gas issues.
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Inspect for leaks: Regularly check all water and gas connections for moisture or signs of leakage.
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Maintain proper temperature settings: Keep the thermostat between 120°F–140°F to prevent scalding and optimize energy efficiency.
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Keep the area clean and ventilated: Ensure airflow around the unit is unobstructed and the space is free from dust and debris.
Damage 
Loss 
Theft 
