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Tankless Water Heater Installation in Southern Ontario
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What a Tankless Installation Involves in an Ontario Home
A tankless water heater is not a like-for-like swap for a tank. The unit fires at four to five times the input of the tank it replaces, so in most homes the gas supply and the venting decide the job rather than the heater itself. These are the seven things we check before quoting.
| What we check | Why it decides the job |
|---|---|
| Gas line capacity | A 40-gallon tank draws roughly 40,000 BTU/h. The tankless units we install run 160,000 to 199,000 BTU/h. If the existing line cannot carry that while the furnace is also firing, it is resized or given a dedicated run. This is the most common added cost on a tankless job. |
| Venting route | Condensing units vent through sealed plastic pipe and can usually go out through a sidewall, which avoids lining a chimney. The distance from the unit to an acceptable exterior wall sets how much pipe and labour the install needs. |
| Condensate drain | A condensing unit produces acidic condensate. It needs a drain within reach, and in most Ontario installs a neutraliser cartridge before that water enters the plumbing. |
| Water hardness | Much of Southern Ontario is on hard water, and scale is what shortens a tankless heat exchanger’s life. We look at whether the home needs treatment alongside the install rather than two years later. |
| Electrical supply | A gas tankless unit still needs a standard receptacle within reach for its controls and fan. On older mechanical-room walls that is occasionally the one thing missing. |
| Isolation valves | Service valves fitted at installation are what turn the annual flush into a 45-minute job instead of a plumbing call. They cost very little at install and a lot to add later. |
| Permit and gas fitting | Gas work is carried out by a licensed gas fitter under the rules of Ontario’s Technical Standards and Safety Authority. Permit requirements depend on the municipality and the scope of the gas and venting work. |
None of this is unusual work, and most Southern Ontario homes take a tankless unit without difficulty. What matters is knowing which of these items applies to your house before you compare quotes, because a quote that leaves the gas line out is not cheaper, it is incomplete.
The Four Tankless Brands We Install and Service
We install and service A. O. Smith, Rinnai, Navien and Noritz tankless water heaters. For most Ontario homes the decision comes down to three things rather than the badge on the front: how the unit copes with hard water, whether recirculation is built in or has to be added, and what the unit actually delivers at a winter temperature rise.
| Series | Maximum input | Efficiency | Output at a 67°F rise | Scale and recirculation |
|---|---|---|---|---|
| A. O. Smith Adapt®+ ATHR-160X3 / 180X3 / 199X3 | 160,000 / 180,000 / 199,000 BTU/h | 0.95 UEF | 4.8 / 5.3 / 5.9 GPM | X3® scale prevention, no annual descaling required. Recirculation on compatible plumbing. |
| Rinnai SENSEI® RX RX160iN / RX199iN | 160,000 / 199,000 BTU/h | 0.97 / 0.98 UEF | Not published alongside the headline figure — see below | Annual descaling. External recirculation loop or pump. |
| Navien NPE-2 NPE-180A2 / 210A2 / 240A2 | 150,000 / 180,000 / 199,900 BTU/h | 0.95 UEF | 4.3 / 5.1 / 5.6 GPM | Annual descaling. ComfortFlow® recirculation pump and buffer tank built into the A2 models. |
| Noritz NR66 / NR71 non-condensing, NRC661 condensing | 140,000 / 180,000 BTU/h; NRC661 to 120,000 | NRC661 0.89 UEF | 5.3 / 6.3 GPM at a 45°F rise — a different basis | Annual descaling. External recirculation. |
A. O. Smith Adapt®+ with X3® Scale Prevention
The one unit here that is designed not to need an annual descale, which matters because scale is what ends a tankless heat exchanger’s life early and much of Southern Ontario is on hard water. If you would rather not book a descaling visit every year, this is the shortlist of one. A. O. Smith also states that X3 extends the unit’s life up to three times compared with a tankless model without it, and that its 15-year limited warranty covers scale-related failures. Models, sizing and the replacement options are on our A. O. Smith tankless water heater page.
Rinnai SENSEI® RX
The highest published efficiency of the four at 0.97 to 0.98 UEF, and the widest installed base in North America, which in practice means parts and technician familiarity are rarely a problem. It needs an annual descale and an external loop if you want recirculation. The RX160iN and RX199iN are covered in detail above.
Navien NPE-2 with ComfortFlow®
The A2 models are the only ones here with a recirculation pump and buffer tank built into the unit. If the problem you are solving is a long wait for hot water at a far bathroom, Navien gets you there without running a dedicated return line through the house, which can be the difference between a straightforward job and a disruptive one. Navien also publishes its flow ratings at a 67°F rise, which is the honest number.
Noritz
Noritz still offers non-condensing models, the NR66 and NR71, alongside the condensing NRC661. A non-condensing unit is occasionally the practical answer where the venting route makes a condensing install awkward and there is an existing suitable flue, though it gives up efficiency and the condensate handling that comes with it. Worth asking about rather than assuming.
Figures above are the manufacturers’ own published specifications, checked on 1 October 2026: A. O. Smith · Rinnai · Navien · Noritz. Model availability and specifications change, so we confirm the current figures for the unit we are quoting.
Already have one of these and it needs fixing rather than replacing? See tankless water heater repair, which covers the common faults and error codes for all four brands.
Why You Cannot Compare the Headline GPM Numbers Between Brands
This is the most common way a tankless unit ends up undersized, and it is neither the brand’s fault nor the installer’s. Manufacturers publish maximum flow at different temperature rises, and a headline flow figure without its rise attached is a marketing number, not a specification.
A. O. Smith publishes both figures for the same heater, which makes the point better than we could. The ATHR-199X3 is rated 10.5 GPM at a 30°F rise and 5.9 GPM at a 67°F rise. Same unit, same spec sheet, nearly half the output.
An Ontario winter is not the 30°F column. Incoming water near 5°C raised to a usable 49°C is roughly a 79°F rise, which is beyond even the published 67°F figure, so the real February output of any unit on this page is lower than the 67°F column above. A 67°F rise from 5°C only reaches about 42°C, which is not a comfortable shower.
None of that is a reason to avoid tankless. It is the reason we size from the temperature rise your address actually needs in February and the fixtures you actually run together, rather than from the largest number on the box. It is also why a unit that was fine in October can disappoint in January: nothing failed, it was sized on the wrong column.
A. O. Smith Tankless Water Heaters with X3™ Technology
Continuous Hot Water. Less Maintenance.
Upgrade your home with the A. O. Smith Adapt®+ tankless water heater, professionally installed by 1st Heat Home Comfort Inc.
Patented X3™ Scale Prevention Technology helps prevent scale buildup, protecting performance and eliminating the need for annual descaling.
A. O. Smith Tankless Water Heaters Benefits
- *Continuous hot water on demand
- X3™ scale prevention—no annual descaling required
- Built-in recirculation pump for compatible plumbing setups
- ENERGY STAR® certified with a 0.95 UEF efficiency rating
- Compact, wall-mounted design
- Natural gas operation, convertible to propane
- 15-year limited heat-exchanger warranty and 5-year limited parts warranty for residential applications
A. O. Smith Tankless Water Heaters models
- ATHR-160X3
- ATHR-180X3
- ATHR-199X3.
We’ll help you choose the right size for your household’s hot-water needs.
Call 289-409-9929 for a free installation quote.
Hot-water capacity depends on incoming water temperature and demand. Recirculation may require additional plumbing or accessories. Manufacturer’s warranty terms apply. Other routine maintenance is still required.
Choose the Right Rinnai Tankless Water Heater for Your Home
Continuous Hot Water. Efficient Performance. More Space.
Upgrade your home’s hot-water system with a Rinnai SENSEI® RX Series tankless water heater, professionally installed by 1st Heat Home Comfort Inc.
Rinnai tankless water heaters heat water as it flows through the unit, delivering continuous hot water without storing it in a large tank. Their compact, wall-mounted design frees up floor space, while condensing technology helps reduce energy waste.
Rinnai RX160iN — For Moderate Hot-Water Demand
The RX160iN offers efficient, on-demand water heating for households with moderate simultaneous hot-water needs.
- Maximum heating input: 160,000 BTU/h
- Efficiency rating: 0.97 UEF
- Maximum rated flow: 9.0 US gallons per minute
- ENERGY STAR® certified
- Compatible with natural gas or propane
This model may be a good fit when fewer showers and hot-water appliances operate at the same time. We assess your household’s usage and incoming water temperature to confirm the right size.
Rinnai RX199iN — More Capacity for Higher Demand
The RX199iN provides greater heating capacity for households that need more hot water at once.
- Maximum heating input: 199,000 BTU/h
- Efficiency rating: 0.98 UEF
- Maximum rated flow: 11.1 US gallons per minute
- ENERGY STAR® certified
- Compatible with natural gas or propane
Its higher heating capacity allows it to deliver more hot water than the RX160iN under the same conditions, making it an option for homes with greater simultaneous demand.
Which Model Is Right for Your Home?
The best choice depends on more than the number of bathrooms. We consider shower flow rates, appliances used at the same time, incoming water temperature, and your home’s gas supply and venting.
Ontario’s colder winter water temperatures reduce the amount of hot water a tankless unit can produce per minute. The maximum flow ratings above are not guaranteed winter delivery rates. Proper sizing helps ensure your system meets your everyday needs.
Does Tankless Mean Instant Hot Water?
Tankless provides continuous hot water within the unit’s capacity, but water still needs time to travel through your pipes to the tap. A compatible recirculation system can help reduce this wait. Ask us about options and any additional equipment your home may require.
Maintenance and Warranty
Regular maintenance helps protect performance and equipment life. Rinnai recommends annual flushing to remove mineral buildup, along with periodic filter checks. Maintenance needs can vary with water quality and usage.
Manufacturer’s limited warranty coverage is subject to the selected model’s terms, installation requirements and application. We can explain the applicable coverage before installation.
Professional Installation by 1st Heat Home Comfort Inc.
We help you select the right model and assess the gas supply, venting, water connections and condensate drainage needed for your installation.
Our own team completes your installation—no subcontractors.
Serving homeowners across Toronto and the Greater Toronto Area.
Call 289-409-9929 for a free installation quote.
Our Recommended Products
Rinnai SENSEI RX160 Tankless Water Heater
- Fuel Type: Natural Gas / Propane
- Maximum Gas Input: 160,000 BTU/h
- Minimum Gas Input: 15,000 BTU/h
- Maximum Flow Rate: Up to 9.0 GPM (34 L/min)
- Minimum Flow Rate: 0.13 GPM (0.5 L/min)
- Dimensions (W × H × D): 18.5 × 30.1 × 11.4 in
- Weight: Approximately 54 lb (24 kg)
- Sound Level: 48 dB
- Water Supply Pressure: 15–150 PSI
Best for: medium-sized homes and moderate to high hot water demand
Rinnai SENSEI RX199 Tankless Water Heater
- Fuel Type: Natural Gas / Propane
- Maximum Gas Input: 199,000 BTU/h
- Minimum Gas Input: 15,000 BTU/h
- Maximum Flow Rate: Up to 11.1 GPM (42 L/min)
- Minimum Flow Rate: 0.13 GPM (0.5 L/min)
- Dimensions (W × H × D): 18.5 × 30.1 × 11.4 in
- Weight: Approximately 55 lb (24.5 kg)
- Sound Level: 49 dB
- Water Supply Pressure: 15–150 PSI
Best for: large homes and high hot water demand with multiple simultaneous users.
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Our Last Tankless Water Heater Installation
Watch real tankless water heater installation projects completed by our experts across Southern Ontario.
TANKLESS WATER HEATER Services Southern Ontario You Can Depend On
Tankless Water Heater Installation
Professional installation of tankless water heaters that ensure proper sizing, safe connections, and reliable hot water performance year-round.
Tankless Water Heater Repair
Fast diagnosis and repair services that restore hot water quickly, addressing ignition issues, flow problems, and system errors.
Tankless Water Heater Maintenance
Preventive maintenance services that improve efficiency, reduce scale buildup, and extend the lifespan of your tankless system.
How Much Hot Water Does Your Home Need?
Choosing the right tankless water heater depends on how many hot-water fixtures may operate at the same time—not only the number of bathrooms in your home.
Every shower, faucet and appliance requires a certain amount of water, measured in GPM (gallons per minute).
Typical Hot-Water Flow Rates
| Fixture or appliance | Typical flow rate |
|---|---|
| Bathroom faucet | 0.5–1.5 GPM |
| Kitchen faucet | 1.5–2.2 GPM |
| Standard shower | 1.8–2.5 GPM |
| Rain or luxury shower | 2.5–4.0+ GPM |
| Dishwasher | 1.0–2.0 GPM |
| Washing machine | 1.5–3.0 GPM |
| Bathtub filler | 4.0–7.0+ GPM |
Actual water usage depends on the fixture, water pressure and whether hot and cold water are being mixed.
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Why Proper Sizing Matters in Southern Ontario
A tankless water heater’s available GPM changes with the incoming water temperature. During an Ontario winter, the incoming groundwater can be much colder. The unit must work harder to raise that water to a comfortable shower temperature, reducing its available hot-water flow.
For this reason, a model advertised at a high maximum GPM may deliver less hot water during the coldest months. Your system should be selected according to its winter-temperature performance, not only its advertised maximum rating.
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What Size Tankless Water Heater Your Home Needs
The number that matters is flow, measured in gallons per minute, and the number your home needs is not the number on the box. A rated maximum flow assumes a mild incoming water temperature. In an Ontario winter the incoming main can sit near 5°C, and lifting that to a usable 49°C uses far more of the burner than the same unit needs in July. Sizing on the summer figure is how a house ends up with a lukewarm shower in February.
| Fixture | Typical flow |
|---|---|
| Low-flow shower | 1.5 to 2.0 GPM |
| Standard shower | 2.0 to 2.5 GPM |
| Kitchen sink | 1.0 to 1.5 GPM |
| Bathroom faucet | 0.5 to 1.0 GPM |
| Dishwasher | 1.0 to 1.5 GPM |
| Washing machine | 1.5 to 2.0 GPM |
Add the fixtures that realistically run at the same time. Two showers together is 4 to 5 GPM before the dishwasher starts. Then apply the winter rise, which is why the Rinnai RX160iN’s 9.0 GPM and the RX199iN’s 11.1 GPM ratings listed above, both from the manufacturer’s published specification, describe a smaller temperature rise than a January morning in Ontario. We size on the rise your address actually needs, not the headline figure.
The Importance of Regular Tankless Water Heater Maintenance
Regular maintenance ensures your tankless water heater delivers instant hot water without temperature fluctuations or pressure drops during daily use.
Servicing helps prevent mineral buildup and internal blockages, allowing your system to respond quickly and maintain consistent hot water flow.
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What Changes the Installed Price
We quote after looking at the gas line, the vent route and the drain, because those three decide most of the difference between one house and the next. A single published price for tankless installation is almost always the price of the easiest possible version of the job.
What moves the number:
- Gas line work. Resizing a run, or adding a dedicated one, is the largest single variable.
- Distance to the vent wall. A unit on an outside wall is a short vent. A unit in the middle of a basement is not.
- What happens to the old tank. An owned tank is removed and disposed of. A rented one has to go back to the rental company, and the contract sets those terms.
- Recirculation. If you want hot water to arrive quickly at a far bathroom, that is a pump and a return line, or a unit with the pump built in.
- Water treatment. Hard water is common across Southern Ontario, and a water softener protects the heat exchanger you just paid for.
- Condensate neutraliser and drain work. Small in itself, occasionally not, depending on where the nearest drain is.
- Permit and inspection. Set by the municipality and the scope of the gas and venting work.
What we will tell you before anyone comes out is whether your home looks like a straightforward install or one of the ones where the gas line is the real project. That takes a few minutes on the phone. Call (289) 409-9929.
Switching From a Tank: What Changes in the House
Most people asking about tankless already have a tank, so the useful question is what actually changes in the house.
- Floor space comes back. A 40 or 50-gallon tank footprint becomes a wall-mounted unit roughly the size of a carry-on suitcase.
- The chimney may come out of service. If the tank was the last appliance venting into that flue and the furnace is already direct-vent, the flue has to be capped or abandoned properly. Quotes sometimes leave this out.
- A rented tank has a contract. Ontario rental water heaters carry buyout and return terms, and that cost belongs in the comparison rather than being discovered afterwards.
- Hot water behaves differently. It does not run out, but there is a short delay while the burner lights and the cooled water already in the pipe clears. A recirculation loop removes that; nothing else does.
- Maintenance changes shape. There is no anode rod to replace, but there is an annual descale unless the unit carries scale-prevention technology.
If replacing the tank with another tank is the better answer for your house, we will say so. See water heater installation for tank options, and water heater maintenance for what servicing either type involves.
Tankless Water Heater Rebates in Ontario
This is the question we are asked most often about tankless, and the answer is not the one most rebate articles give.
Checked 30 September 2026: the Home Renovation Savings Program’s water-heater rebate is $500 for a qualifying ENERGY STAR certified heat pump water heater. A gas tankless water heater is not listed as an eligible upgrade on Save on Energy’s own programme page, and Enbridge Gas does not currently list a tankless water heater rebate either.
Third-party rebate articles still quote tankless amounts. Those figures come from Enbridge’s earlier Home Efficiency Rebate programme, which closed to new applicants in 2024. Where a rebate article disagrees with Save on Energy, believe Save on Energy.
Two upgrades in this category do carry rebate money, if efficiency is what you are after:
- A heat pump water heater, at $500 under the Home Renovation Savings Program.
- A cold-climate heat pump for space heating, at up to $7,500 depending on how your home is heated now. Our Ontario heat pump rebate page carries the current amounts by heating source, and Home Renovation Savings Program explains the programme’s two paths and why the choice between them matters.
1st Heat Home Comfort helps eligible Ontario homeowners access available Home Renovation Savings rebates for qualifying cold-climate heat-pump installations. Our team coordinates the process from eligibility review and pre-approval through installation, final documentation and rebate submission.
All rebates remain subject to program eligibility, approval and current HRS terms and conditions. Figures were checked on 30 September 2026 against Save on Energy and Enbridge Gas.
Tankless Water Heater Installation Across Southern Ontario
We install tankless water heaters across Southern Ontario from our base in Concord. Incoming water temperature, water hardness and the age of the gas supply all vary by area, which is why the sizing conversation starts with where you are.
Ajax · Barrie · Brampton · Brantford · East Gwillimbury · Guelph · Hamilton · Kawartha Lakes · Kingston · Kitchener · London · Markham · Mississauga · Niagara · Oakville · Orangeville · Oshawa · Ottawa · Peterborough · Richmond Hill · Smiths Falls · St. Catharines · Sudbury · Vaughan · Waterloo · Welland
If your town is not on the list, call (289) 409-9929 and we will tell you honestly whether we cover it.
Tankless Water Heater Installation: Common Questions
How long does a tankless water heater last?
Around 20 years with annual servicing, against 10 to 12 for a typical tank. Scale is what shortens that, which is why water hardness matters here. The units we install carry a 15-year limited heat-exchanger warranty in residential use, under the manufacturer’s own terms.
What size tankless water heater do I need?
Size on flow, not on the number of people in the house. Add the fixtures that realistically run at the same time, then allow for the winter temperature rise, because an Ontario January asks far more of the burner than July does. Two simultaneous showers is usually 4 to 5 GPM before anything else runs.
Does a tankless water heater need a bigger gas line?
Often, yes. A tank draws roughly 40,000 BTU/h and a tankless unit 160,000 to 199,000. If the existing line cannot carry that while the furnace is firing, it is resized or given a dedicated run. This is the most common added cost, and we check it before quoting rather than after.
Is there a rebate for a tankless water heater in Ontario?
Not currently. Checked 30 September 2026, the Home Renovation Savings Program’s water-heater rebate is $500 for a qualifying ENERGY STAR heat pump water heater, and a gas tankless unit is not listed as an eligible upgrade. Enbridge Gas does not list a tankless rebate either.
Is a tankless water heater worth it in Ontario?
It is worth it if you run out of hot water, want the floor space back, or plan to stay long enough for the longer service life to count. If your tank is owned, working, and the house has one bathroom, a like-for-like tank replacement is usually the better value, and we will say so.
How often does a tankless water heater need servicing?
Once a year for most units, to descale the heat exchanger and check the venting and condensate path. Models with scale-prevention technology reduce or remove the descaling step. Isolation valves fitted at installation are what keep that annual service quick and inexpensive.
Is Navien or Rinnai better for a tankless water heater?
Neither is better across the board. Rinnai publishes the higher efficiency, 0.97 to 0.98 UEF against Navien’s 0.95. Navien’s A2 models have a recirculation pump and buffer tank built into the unit, so they fix a slow-hot-water complaint without running a return line through the house. We choose on the house, not the badge.
Which tankless water heater brands do you install and service?
A. O. Smith, Rinnai, Navien and Noritz, across Southern Ontario, for installation, repair and annual maintenance, including units another company installed. If you already have one of these and it needs servicing rather than replacing, that is the cheaper conversation and we will tell you so.
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Our Office:
- 3300 Steeles Avenue West, Unit 11B-4 Concord, Ontario L4K 2Y4 Canada
- (289) 409-9929
