Most Ontario homeowners shopping for the best tankless water heater focus on flow rate and price. Those matter, but they’re not the whole picture.
Cold winter inlet temperatures, gas line capacity, venting routes, water hardness, and household demand all affect a unit’s performance. Getting those details wrong means a system that can’t keep up.
Dr HVAC’s water heater installation team works with homeowners across the GTA to properly size, select, and install tankless water heaters.
Unlike conventional tanks that keep water heated around the clock, tankless units heat water only when there’s demand. That means less wasted energy, a smaller footprint, and a continuous hot water supply, provided the unit is properly matched to your home.
Written by our Toronto plumbers, this guide compares trusted brands and popular models, then covers efficiency, sizing, cost, gas versus electric options, and whether to buy or rent your water heater.
What Are Some Trusted Tankless Water Heater Brands?
Choosing the right brand is the first step. Of the options available in Ontario, four stand out for reliability, efficiency, and service support: Navien, Rinnai, Noritz, and John Wood.
Here’s how they compare at a glance:
| Name | Performance (BTU/h) | Cost ($, $$, $$$) | Efficiency (UEF) | Warranty |
| Navien | Up to 199,900 | $$$ | 0.93 – 0.96 | 15 Years |
| Rinnai | Up to 199,000 | $$$ | 0.91 – 0.95 | 15 Years |
| Noritz | Up to 199,900 | $$ | 0.95 – 0.98 | 25 Years |
| John Wood | Up to 199,000 | $$ | 0.93 – 0.95 | 15 Years |
Note: UEF (Uniform Energy Factor) measures efficiency: the higher the number, the more efficient the unit. Figures above reflect flagship residential models. Specs vary by model.
Navien Tankless Water Heater
Navien is one of the most recognizable names in condensing gas tankless water heaters. Its NPE-S is known for high efficiency, strong output, dual stainless steel heat exchangers, and flexible venting options. Navien tankless water heaters offer a seamless supply of hot water, ensuring comfort and convenience in your home.
Rinnai Tankless Water Heater
Rinnai has a long track record in Canada and offers a wide range of tankless water heaters for households of different sizes. Rinnai tankless units are commonly used in homes that need compact installation, strong efficiency, and dependable hot water delivery. The RU130iN model stands out for its exceptional efficiency and advanced features.
Noritz Tankless Water Heaters
Noritz is a strong option for homeowners focused on retrofit installations and long warranty coverage. The Noritz EZ Series and EZ111 model make replacing a conventional tank water heater with a tankless unit more straightforward.
Offering a blend of performance, efficiency, and reliability, Noritz tankless water heaters are engineered to meet the hot water demands of modern households.
John Wood Tankless Water Heaters
John Wood is a familiar name in the Canadian water heater market. John Wood tankless water heaters are often positioned as practical, compact options for homeowners who want a reliable system from a brand with Canadian market recognition.
With features such as modulating gas valves and high-efficiency burners, John Wood heaters optimize energy use, resulting in lower utility bills and reduced environmental impact. Their durable construction and reliability make them a popular choice for both residential and commercial installations.
Best Tankless Water Heater Units
Below are three units we recommend for most Ontario homes. Each offers a distinct combination of capacity, efficiency, and value.
| Feature | Navien NPE-S2 Series | Noritz EZ111DV | Rinnai RU130iN | Rinnai RX130iN |
| Unit Type | Condensing Gas | Condensing Gas | Condensing Gas | Condensing Gas |
| BTU Input | 13,300 – 199,900 | 12,800 – 199,900 | 15,000 – 130,000 | 15,000 – 130,000 |
| Max Flow Rate (GPM) | Up to 11.2 | Up to 11.1 | Up to 6.6-7.0 | Up to 7.1 |
| UEF Rating | Up to 0.96 | Up to 0.98 | 0.91 | 0.97 |
| Heat Exchanger | Dual Stainless Steel | Dual Stainless Steel | Stainless Steel | Dual Stainless Steel |
| Venting Material | PVC, CPVC, PP, stainless steel | PVC, CPVC, PP | PVC, CPVC, PP, stainless steel | PVC, CPVC, PP, stainless steel |
| Warranty | 15 Year Heat Exchanger / 5 Year Parts | 25 Year Heat Exchanger / 5 Year Parts | 15 Year Heat Exchanger / 5 Year Parts | 15 Year Heat Exchanger / 5 Year Parts |
| Best For… | Large homes, high demand | Retrofit installs, value | Smaller homes, medium demand | Smaller homes, medium demand |
Navien NPE-S2 Series
Models from Navien’s NPE-S2 Series are what we most commonly recommend for larger GTA homes.
For example, the NPE-240S2 features a BTU input range of 13,300 to 199,900 and a flow rate of 11.2 GPM, it can comfortably supply multiple fixtures running simultaneously.
Its dual stainless steel heat exchangers and 2-inch PVC venting compatibility keep installation costs down while delivering a 0.96 UEF efficiency rating. The EZNav control panel makes monitoring and troubleshooting straightforward.
Plus, Navien backs the NPE-240S2 with a 15-year heat exchanger warranty and 5-year parts coverage for residential installations.
Noritz EZ111DV
The EZ111 earns its reputation on two points: its 25-year heat exchanger warranty (one of the best in the industry) and a design that makes replacing a conventional tank straightforward.
Top-mounted water connections align with where tank connections typically sit, which reduces plumbing changes during a retrofit. Its Steady BTU Mode automatically reduces BTU output when incoming water temperatures are high.
The EZ111DV delivers 11.1 GPM with a UEF of 0.98, exceeding Navien’s efficiency.
Rinnai RU130iN
The RU130iN is a mid-capacity unit from Rinnai’s SENSEI series. At 130,000 BTU and 6.6 GPM, it’s well-suited for homes with moderate hot water demand.
Its fibre mesh premix burner provides even flame distribution for stable performance, and the flexible venting system accommodates concentric, direct, room-air, or common-vent configurations. Circ-Logic compatibility means it can be paired with an external pump to deliver hot water faster through a recirculation setup.
How Does A Tankless Water Heater Work?
Tankless water heaters operate on demand, heating water only when it is needed.
When a hot water tap is turned on, cold water flows through a heat exchanger, where it is rapidly heated by a gas burner or electric element. This process ensures a continuous and instantaneous supply of hot water, eliminating the need for a storage tank.
A tankless water heater looks very different from a traditional hot water tank. Instead of a large cylindrical tank, you’ll see a compact box, usually mounted on the wall, with a network of pipes and valves attached.
Here’s a quick breakdown of how a tankless heater works:
- Turning on a hot water faucet makes water flow into the heater.
- This activates the flow sensor, which in turn triggers the control panel.
- The control panel switches on the fan.
- The fan draws in outside air, opens the gas valve, and ignites the gas burner.
- Exhaust gases from the combustion are vented outdoors, through either an exterior wall or the roof.
- The gas burner produces heat, which the heat exchanger transfers to the incoming water.
- The mixing valve tempers the superheated water to avoid scalding.
- The water is piped to your shower or faucet.
- You enjoy a continuous flow of on-demand hot water for as long as you like.
- When the fixture is turned off, the hot water flow stops and the gas burner shuts down.
Unlike traditional tank heaters, a tankless water heater does not maintain a large volume of water at a constant temperature all day. It sits idle between uses, then turns on when hot water is needed.
Why Install A Tankless Water Heater?
Glad you asked! There are tons of benefits to installing a tankless water heater.
Better Energy Efficiency
Conventional tank water heaters are among the largest energy consumers in a home, second only to heating and cooling systems. They keep a full tank of water heated around the clock, even when no one needs it.
Tankless units eliminate that standby energy loss because they heat water only when there is demand.
In fact, ENERGY STAR-certified tankless water heaters use approximately 30% less energy on average than standard storage-tank models. Over the unit’s lifetime, those energy savings can meaningfully reduce operating costs, especially in homes with high hot-water demand.
Continuous Hot Water
Imagine being the last one in your household to take a shower… and there’s still hot water!
Unlike storage tank heaters, a properly sized tankless water heater provides hot water on demand for as long as you need it. This means you’ll never run out of hot water and have to suffer through a cold shower.
However, the key phrase is “properly sized”. If the unit is too small for the home, it may struggle when multiple fixtures run at once.
Space Savings
Tankless water heaters are compact and wall-mounted, saving valuable space.
About the size of a carry-on suitcase, tankless water heaters have a slim profile and can easily fit into a closet (as long as they’re properly vented). This frees up space, which is especially important if you live in a small house or condo.
Longer Lifespan
Tankless water heaters last longer compared to storage tank heaters. With proper maintenance, they can provide hot water on demand for two decades or more.
Tankless water heaters last longer because they aren’t exposed to the same wear and tear as those with a large volume of heated water.
Less Chance of Flooding
With no tank to burst, there is very little risk of flooding.
Tankless heaters don’t store large amounts of water. Even if they develop a water heater leak, it usually won’t be catastrophic, as they’re usually due for replacement when they reach an advanced age.
Pairing the unit with a drain pan further reduces any risk to your home.
How Long Do Tankless Heaters Last?
A well-maintained tankless hot water heater can last up to 20 years or more. Regular maintenance, such as flushing the system and checking for mineral buildup, can greatly extend your heater’s lifespan.
Tankless water heaters are known for their durability and are a reliable and cost-effective choice for homeowners. Their lifespan is longer than that of conventional water heaters, which is around 10-15 years.
How Much Does A Tankless Water Heater Cost?
The cost of installing a tankless water heater in Canada can range from $2,500 to $7,500.
The range depends on several factors, including the unit’s size, energy efficiency rating, brand, and features. High-end, premium-brand models with Wi-Fi connectivity and precise temperature control will be pricier.
The cost of professional installation, essential for ensuring your installation is done to code, also needs to be factored in. A more complex installation will have added costs compared to a straightforward one.
Other cost factors might be needed upgrades to your home’s plumbing and electrical systems to accommodate a new unit. Some homes may require additional venting or gas line modifications, which can also increase the overall cost.
Despite these upfront costs, most homeowners find that the long-term energy bill savings and the convenience of on-demand hot water make tankless water heaters a worthwhile investment.
Gas Vs. Electric Tankless Water Heaters
Natural Gas Tankless Water Heater
Pros:
- High flow rates for multiple applications.
- Energy-efficient and cost-effective in regions with access to natural gas.
- Ideal for larger households with higher hot water demands.
Cons:
- Higher upfront cost and installation complexity compared to electric models.
- Requires proper venting for exhaust gases.
Electric Tankless Water Heaters
Pros:
- Simplified installation and lower upfront cost.
- Suitable for smaller households or areas without natural gas access.
- Highly efficient in regions with lower electricity rates.
Cons:
- Limited flow rates, which may be insufficient for simultaneous hot water usage in larger households.
- May require electrical upgrades to support higher amperage.
Consider your household size, hot water demand, and available energy sources when choosing between gas and electric tankless water heaters.
Condensing Vs. Non-Condensing Tankless Water Heaters
Condensing Tankless Water Heaters
Pros:
- Higher energy efficiency, with an efficiency rating of over 90%.
- Extract additional heat from exhaust gases for more efficient operation.
- Lower greenhouse gas emissions.
Cons:
- Higher upfront cost compared to non-condensing models.
Non-Condensing Tankless Water Heaters
Pros:
- Lower upfront cost compared to condensing models.
- Still highly efficient compared to traditional storage tank water heaters.
Cons:
- Slightly lower energy efficiency compared to condensing models.
Condensing tankless water heaters are the more energy-efficient option, making them a greener choice for eco-conscious homeowners. However, they come with a higher initial investment.
What Is The Flow Rate Of A Tankless Unit?
Flow rate is the number of gallons of hot water a unit can deliver per minute (GPM). It’s one of the most important specs to understand when sizing a tankless heater for your home.
A single shower typically draws 1.5–2.5 GPM, though actual flow depends on the showerhead and plumbing fixtures. Running a shower and a dishwasher at the same time might require 3.5–5 GPM. A large household with high simultaneous demand could need 8 GPM or more during peak morning hours.
However, flow rate alone doesn’t tell the whole story. Temperature rise matters too.
Ontario’s cold water supply is considerably colder in winter than in summer, which affects how hard the heater has to work to reach your target temperature. Many product tables advertise maximum GPM at a favourable temperature rise.
Ontario winter inlet temperatures can be significantly colder, which reduces real-world flow, so always confirm sizing against your actual cold-water temperature, not the spec sheet maximum.
Do I Need To Worry About Sizing?
Yes, proper sizing is crucial when selecting a tankless water heater. It ensures the unit can meet your household’s hot water demands. Factors to consider include:
Peak Demand: Calculate the maximum number of hot-water fixtures and appliances that can be used simultaneously.
Temperature Rise: Determine the temperature rise needed to achieve the desired hot water temperature in your region.
Flow Rate: Ensure the tankless water heater can meet your household’s flow-rate demands.
Consult a Dr HVAC technician or use sizing calculators provided by manufacturers to accurately determine the right size for your tankless water heater.
Where To Buy A Tankless Water Heater?
When it comes to buying and installing a tankless water heater in Ontario, the unit and the installation are equally important.
A licensed HVAC technician will assess your home’s gas supply, venting configuration, and hot water demand before recommending a model. Professional installation also ensures the unit meets local building codes, which matters for insurance purposes and future resale.
On the buying-versus-renting question: purchasing a unit costs more upfront but gives you full ownership, no monthly fees, and the ability to choose the exact model and features you want.
Renting reduces the upfront cost and typically includes maintenance coverage, but monthly payments add up over time and may exceed the purchase price over the long term.
Both paths are legitimate. Your decision should factor in how long you plan to stay in the home, whether you want to avoid maintenance responsibility, and what your budget allows.
Choose The Best Tankless Water Heater with Dr HVAC
The best tankless water heater is not always the biggest or most expensive model. It is the unit that fits your home, your hot water demand, your installation requirements, and your budget.
If you live in Toronto, Brampton, Mississauga, or elsewhere in the Greater Toronto Area, Dr HVAC can help you compare your options and choose the right tankless water heater for your home.
Our certified team can assess your current system, recommend the right unit, and complete your tankless water heater installation from start to finish.
Contact Dr HVAC today for an obligation-free consultation and quote!
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