How long do tankless water heaters last?

Tankless water heaters typically last 15 to 20 years with proper maintenance, which is nearly double the 8 to 12 year lifespan of traditional tank water heaters. Annual descaling and filter cleaning help maximize longevity.

Are tankless water heaters worth the cost?

Yes, tankless water heaters are a worthwhile investment for most homes. They reduce energy consumption by 24 to 34 percent compared to tank heaters, provide unlimited hot water on demand, and take up significantly less space. The higher upfront cost is offset by lower monthly energy bills and longer lifespan.

How much does tankless water heater installation cost?

Tankless water heater installation in the GTA typically costs between $3,000 and $5,500, depending on the model, venting requirements, and whether gas line modifications are needed. Furnace King provides free in-home estimates.

Can a tankless water heater supply enough hot water for my family?

Modern tankless water heaters can deliver 7 to 10 gallons per minute, which is sufficient for most households to run multiple fixtures simultaneously. For larger homes with high hot water demand, we may recommend a higher-capacity unit or multiple units.

Do tankless water heaters need maintenance?

Yes, tankless water heaters should be descaled annually, especially in areas with hard water like Mississauga. Mineral buildup reduces efficiency and can damage internal components. Our maintenance service includes full descaling, filter cleaning, and performance testing.

Can I switch from a tank to a tankless water heater?

Yes — Furnace King handles full tank-to-tankless conversions throughout Mississauga and the GTA. The process includes a gas line assessment (many homes need an upgrade from 3/4-inch to 1-inch gas line), venting modifications for direct-vent exhaust, electrical connection for the control board, and all required TSSA permits. A typical conversion costs $3,500–$5,500 depending on gas line and venting requirements. Most conversions are completed in one to two days.

What size tankless water heater do I need?

The right size depends on your household's peak hot water flow rate and the incoming water temperature. In the GTA, groundwater drops to approximately 4 degrees Celsius in winter, which means your tankless unit needs higher BTU output to reach comfortable temperatures. A 199,000 BTU unit can typically handle three to four fixtures running simultaneously. Furnace King sizes every installation based on your specific household demand, number of bathrooms, and appliance requirements to ensure you never run out of hot water.

Tankless Water Heater Installation & Repair in Mississauga & the GTA

Tankless Water Heater

Do you run out of hot water, or struggle with not being able to shower and do laundry at the same time? A tankless water heater eliminates these problems by heating water on demand — the moment you turn on the tap, a high-powered gas burner activates and delivers hot water continuously. There is no standby energy loss from keeping a large tank heated around the clock, which is why Natural Resources Canada (NRCan) reports tankless units save 24–34 percent on energy costs compared to conventional tank water heaters.

Beyond energy savings, tankless systems offer real practical advantages for homeowners across the GTA. You get an endless supply of hot water — no more cold surprises mid-shower when someone starts the dishwasher. The compact, wall-mounted design frees up valuable floor space in your basement or utility room. And with a lifespan of 20 years or more (nearly double the 8–12 years you can expect from a tank), a tankless water heater is a long-term investment that pays for itself over time. If you are weighing both options, our traditional vs tankless water heater comparison breaks down the differences in detail.

For over 43 years, Furnace King Home Services has been the trusted choice for heating, cooling, and plumbing services in Mississauga and the Greater Toronto Area. Our technicians are fully licensed and certified for gas tankless water heater installation, repair, and annual maintenance. Whether you are upgrading from an old tank or installing a tankless system in a new build, we handle the entire process — from sizing and gas line assessment to TSSA-compliant installation and post-install testing — so you can enjoy reliable hot water without the hassle.

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Tankless Water Heater Installation Process

Every tankless water heater installation begins with a thorough assessment of your home’s infrastructure. Our technician evaluates your gas line capacity — many GTA homes have a 1/2-inch or 3/4-inch gas line that needs to be upgraded to a 1-inch line to deliver the higher BTU demand of a tankless unit. We also assess venting requirements and test your water hardness, since Mississauga’s moderately hard water affects long-term performance.

If a gas line upgrade is needed, our licensed gas fitters handle the work in full compliance with TSSA (Technical Standards and Safety Authority) regulations. All gas appliance installations in Ontario require permits, and Furnace King manages the entire permitting process on your behalf. For venting, we typically install direct-vent systems using PVC or stainless steel through an exterior wall — a cleaner, more efficient approach than traditional chimney venting.

A standard tankless water heater swap is usually completed in one day. If gas line modifications or additional venting work is required, the project may take one to two days. We test every installation for gas leaks, proper combustion, and accurate temperature output before signing off. Thinking about the right timing for your project? Read our guide on when to schedule your tankless water heater installation in the GTA.

Energy Efficiencies

When choosing a new water heater for your home, energy efficiency is one of the most important factors to consider — and tankless technology leads the way. According to NRCan, tankless water heaters reduce energy consumption by 24–34 percent compared to conventional storage tanks. The reason is simple: a tank water heater burns gas continuously to keep 40–50 gallons of water hot, whether you need it or not. A tankless unit fires only when you open the tap, eliminating standby heat loss entirely.

Modern condensing tankless models go even further. They capture heat from exhaust gases that a standard unit would vent outside, squeezing extra efficiency from every cubic metre of natural gas. With Ontario’s natural gas prices among the highest in Canada, these savings add up quickly. Most homeowners in the GTA see a break-even point of 5–7 years on energy savings alone — and since the unit lasts 20+ years, that means over a decade of lower utility bills after payback. Check our temperature settings guide to optimize your system for maximum efficiency.

Many homeowners are learning about tankless technology for the first time, and that is completely normal. Our team will walk you through every detail so you can make a confident decision. When you are ready to make the switch, our certified technicians will help you choose the perfect system for your household’s hot water demand and budget. We also provide ongoing tankless water heater maintenance — including annual descaling and filter cleaning — to keep your unit running at peak efficiency for years to come.

The tankless water heater only consumes gas when hot water is needed. Older tanks are always running so they are able to keep that tank of water at a certain temperature – whether or not you have the need for it.
Another advantage of a tankless water heater is the fact that you will never run out of hot water.
Tankless water heaters also have a much longer lifespan. While traditional tank water heaters last for about seven years, modern tankless water heaters can last around 20 years, if not more.

Tankless Water Heater Brands We Install

Furnace King installs and services all major tankless water heater brands trusted by Canadian homeowners:

Navien (NCB Series) — The most popular choice in the GTA, featuring a built-in recirculation pump for instant hot water, WiFi-enabled monitoring, and industry-leading energy efficiency ratings.

Rinnai (Sensei Series) — Known for rock-solid reliability, the Sensei line offers WiFi monitoring, ThermaCirc360 recirculation technology, and one of the most compact designs on the market.

Rheem (Prestige Series) — Features self-cleaning technology that reduces mineral buildup, EcoNet smart connectivity for remote control, and a built-in leak detection sensor.

All models we install meet or exceed NRCan energy efficiency standards and come with full manufacturer warranties. Not sure which brand is right for you? Use our HVAC cost estimator to compare options, or call us for a free in-home consultation.

Tank vs Tankless: Which Is Right for You?

Choosing between a traditional tank water heater and a tankless system comes down to your budget, hot water needs, and long-term goals. Here is how they compare:

Upfront cost: A tank water heater typically costs $1,200–$2,500 installed, while a tankless unit runs $3,000–$5,500 depending on model and gas line requirements. The higher initial investment in tankless is offset by significantly lower operating costs over time.

Monthly energy bills: Tankless units use 24–34 percent less energy because they only heat water on demand. For an average GTA household, that translates to $150–$300 in annual savings on natural gas.

Lifespan: Tank water heaters last 8–12 years before corrosion and sediment buildup force a replacement. Tankless units last 20+ years with proper maintenance — meaning you may replace a tank heater twice in the same period.

Hot water supply: A 50-gallon tank can run out during peak usage. A tankless system delivers unlimited hot water, no matter how many showers, loads of laundry, or dishwasher cycles are running simultaneously.

Best candidates for tankless: families of three or more, homes with multiple bathrooms, households with simultaneous hot water demand, and anyone planning a renovation or new build. If your current tank is showing signs it needs replacing, now is the ideal time to upgrade. Still unsure? Read our repair vs replace decision guide for a step-by-step breakdown.

Are you experiencing a water heater emergency?

We are available 24-7. Click below to access our emergency repair services for your heating systems.

Tankless Water Heater Service Across the GTA

Furnace King provides tankless water heater installation, repair, and maintenance across the Greater Toronto Area. We proudly serve homeowners in Mississauga, Brampton, Etobicoke, Oakville, Burlington, Milton, Toronto, and Vaughan. With over 43 years of experience and a fleet of fully stocked service vehicles, our licensed technicians can usually reach your home the same day. Whether you need a brand-new tankless installation or emergency heating services, Furnace King is the GTA’s trusted name in home comfort.