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A.O. Smith ATHR-199X3

Advanced Hybrid Tankless Water Heater

The A.O. Smith ATHR-199X3 combines advanced hybrid condensing technology with intelligent recirculation for instant hot water at every fixture. Up to 10.3 GPM, 199,000 BTU input, and 0.93 UEF — built for Canadian homes that demand reliability and performance.

A.O. Smith ATHR-199X3 Tankless Water Heater
Up to 10.3 GPM
199,000 BTU Input
0.93 UEF
Recirculation Built-In

Overview

The A.O. Smith ATHR-199X3 is an advanced hybrid tankless water heater with built-in recirculation technology. It heats water on demand while maintaining a ready supply in the pipes — so you get hot water faster at every fixture with zero tank storage.

Built-in recirculation — hot water reaches fixtures faster, less water wasted
Up to 10.3 GPM — handles large households with ease
0.93 UEF — condensing technology for maximum gas efficiency
Self-diagnostic system — error codes and maintenance alerts on the display

Key Features

Instant Hot Water
Built-in recirculation keeps hot water ready in the pipes so you don't wait 30-60 seconds for it to arrive. Less water wasted, more convenience. Programmable schedule runs recirculation only when you need it.
Hybrid Condensing
Advanced hybrid heat exchanger design achieves 0.93 UEF while maintaining high flow rates. Condensing technology captures heat from exhaust gases for maximum efficiency.
Self-Diagnostics
The built-in control panel displays real-time status, error codes, and maintenance reminders. No guessing — the unit tells you exactly what it needs. H&C can often diagnose issues remotely before dispatching a technician.
Space Savings
Mounts on an interior or exterior wall — freeing up the floor space a traditional 40-60 gallon tank occupies. Perfect for utility closets, garages, or mechanical rooms.
Scale Detection
Built-in scale detection alerts you before mineral buildup affects performance. Scheduled flushing keeps the unit running at peak efficiency for 15+ years.
15-Year Heat Exchanger Warranty
A.O. Smith backs the ATHR-199X3 with an industry-leading 15-year residential heat exchanger warranty and 5 years on parts. H&C handles all warranty registration for you.

Perfect If You're Looking To…

Replace a bulky tank that runs out of hot water. Free up space in your basement or utility room. Cut gas bills with condensing efficiency. Support a growing family that needs hot water on demand.

Specifications

Max Flow Rate10.3 GPM
BTU Input199,000 BTU/h
UEF0.93
Min Activation0.5 GPM
Temp Rise at Max35°F
Venting3"/5" PVC
Gas TypeNG / LP
Voltage120V 60Hz
Wi-FiOptional
Model NumberATHR-199X3
Why A.O. Smith

Trusted Name in Hot Water

American Heritage

A.O. Smith has been building water heaters since 1874 — nearly 150 years of continuous innovation. The ATHR-199X3 represents the latest in their advanced tankless line, combining proven reliability with modern efficiency.

Professional Installation

H&C's licensed technicians are factory-trained on A.O. Smith tankless systems. Proper gas sizing, venting, and recirculation setup are critical — we get it right so your system performs as rated.

Financing Available

Flexible payment options make the switch to heat pump technology affordable. Ask about our low monthly payment plans — combine with government rebates to reduce your out-of-pocket cost even further.

Not Sure Which Size
Is Right for Your Home?

Sizing a tankless system correctly depends on your household's peak hot water demand — how many showers, faucets, and appliances run simultaneously. Our licensed technicians assess your needs and recommend the right unit and gas line sizing for reliable, endless hot water.

Book a Free Home AssessmentCall 1-855-539-4328
FAQ

Frequently Asked Questions

How does a tankless water heater work?
Instead of storing 40-60 gallons of preheated water, a tankless unit heats water on demand as it flows through the heat exchanger. When you turn on a hot water tap, cold water enters the unit, gets heated instantly, and flows to your fixture. When you turn it off, the unit shuts down — no standby energy waste.
Will I really never run out of hot water?
Correct — as long as you stay within the unit's flow rate capacity. The RL94eP delivers up to 9.8 GPM, which is enough for 3+ simultaneous showers in most Canadian homes. H&C sizes the unit to your household's peak demand so you never experience a cold surprise.
How much will I save on energy bills?
Most homeowners save 20-40% on water heating costs compared to a standard tank. Tank water heaters lose heat 24/7 through the tank walls (standby loss). A tankless unit only burns gas when you need hot water. The savings add up over the 15-20 year lifespan of the unit.
Can I replace my tank water heater with a tankless?
Yes — H&C handles the full conversion. We remove the old tank, upgrade your gas line if needed, install the new unit with proper venting, and commission the system. Most conversions are completed in a single day.
What maintenance does a tankless unit need?
Annual flushing with food-grade vinegar removes mineral scale from the heat exchanger. In hard water areas, H&C recommends installing a scale prevention system. We offer annual maintenance plans that keep your unit running at peak efficiency.
How long does installation take?
A tank-to-tankless conversion typically takes one day. This includes removing the old tank, upgrading the gas line (if needed), mounting the new unit, running the vent, and commissioning. H&C handles all permits and inspections.
Customer Reviews

What GTA Homeowners Say
About Their Tankless System

5.0across Google & Facebook

"The A.O. Smith with built-in recirculation was exactly what we needed. Hot water at every faucet in under 5 seconds — no more running the tap waiting. H&C set up the recirculation schedule perfectly."

Priya S.
Markham · Google Review

"Chose the ATHR-199X3 over the Rinnai because of the built-in recirc pump. One less thing to install separately. H&C had it up and running in a day. Very impressed with the build quality."

Dave & Karen L.
Etobicoke · Facebook Review

"The self-diagnostic display is great — tells you exactly what's happening. Three years in and it's been completely trouble-free. Our gas bills are way lower than with our old 50-gallon tank."

James T.
Richmond Hill · Google Review

"H&C recommended the A.O. Smith for our 3-bathroom home. The 15-year heat exchanger warranty sealed the deal. Endless hot water and the recirculation means no more cold water surprises."

Nadia & Omar K.
Vaughan · Yelp Review

"Upgraded from an old tank to the ATHR-199X3. The instant hot water from the recirculation feature is a game-changer. H&C did a clean install and walked us through the controls."

Rob C.
Toronto · Google Review
View All Reviews on Google →

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Tankless Consultation

Tell us about your household and hot water needs. We'll recommend the right A.O. Smith tankless system and provide a clear, no-obligation estimate — including recirculation setup.

Free in-home hot water assessment
Flow rate sizing for your household
Response within 2 hours
Licensed & A.O. Smith-trained technicians
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