A conventional water heater stores 40 to 60 gallons of water in a tank and keeps it heated around the clock — whether you need hot water or not. That constant heating costs you money every single day, even while you're at work or asleep.

A tankless water heater — also called an on-demand or instantaneous water heater — works completely differently. Instead of storing hot water, it heats water directly as it flows through the unit. The moment you turn on a faucet, the system activates. The moment you turn it off, it shuts down. No standby energy loss. No cold showers. Just hot water, whenever you need it.

Here's what happens the second you open the hot water tap:

1. Water flow is detected. A flow sensor inside the unit detects that cold water has entered the system.
2. The burner or heating element activates. Gas-powered units ignite a burner; electric units switch on a heating element. Either way, the process begins instantly.
3. Water passes through a heat exchanger. Cold water travels through a series of coils or pipes surrounding the burner or element. This is where the heat transfer happens — rapidly and efficiently.
4. Hot water is delivered to your tap. Within a few seconds, heated water reaches your faucet, shower, or appliance at your desired temperature.
5. The system shuts off automatically. When you close the tap, water flow stops, and the unit powers down completely — consuming zero energy until the next use.

There are two main types of tankless water heaters available to Ontario homeowners:

Natural Gas Tankless Water Heaters are the most popular choice in the GTA and broader Ontario market. They use a gas burner to heat water and can handle high-demand households — multiple showers, dishwashers, and laundry running at the same time. Brands like Rinnai and Navien are industry leaders, offering energy efficiencies up to 96%. Most gas-powered units connect to your existing Enbridge gas line.

Electric Tankless Water Heaters work well for smaller households or as point-of-use units installed close to a single fixture. They require no gas line or venting but may need an electrical panel upgrade. They're a strong option if your home runs on electricity and you want to eliminate gas entirely.

A tankless water heater is one of the smartest investments you can make for your home. Here's why thousands of homeowners across Toronto, the GTA, Hamilton, Ottawa, London, and Waterloo have already upgraded:

• Unlimited hot water. No more cold showers or waiting for a tank to reheat. Hot water flows continuously for as long as you need it.
• Lower energy bills. Tankless units are up to 95% energy-efficient compared to roughly 60–65% for a traditional tank. A typical Ontario family in a 2,500 sq. ft. home can save hundreds of dollars per year on water heating alone.
• Compact, space-saving design. Tankless units are wall-mounted and roughly the size of a suitcase — freeing up valuable space in your utility room, basement, or closet.
• Longer lifespan. A quality tankless heater lasts 20 to 25 years — roughly twice as long as a conventional storage tank that typically lasts 8 to 12 years.
• No risk of tank leaks or flooding. Traditional tanks hold 40 to 60 gallons of water that can rupture and flood your home. With no storage tank, that risk is completely eliminated.
• Environmentally friendly. Using less energy means a smaller carbon footprint — an important consideration as Ontario continues to push for greener homes.

Choosing the right size comes down to your household's peak hot water demand — that is, how much hot water you might need simultaneously at any given moment. This is measured in gallons per minute (GPM).

For example, a shower typically uses 1.5 to 2 GPM, a dishwasher about 1.5 GPM, and a washing machine around 2 GPM. If two showers are running at the same time in your home, you need a unit that can handle at least 3–4 GPM. Gas models from Rinnai and Navien — the brands we install at Constant Home Comfort — are rated from 5 to 11 GPM, making them ideal for most Ontario households.

Our HVAC specialists will assess your home's water usage and recommend the exact model and size that matches your needs. We take the guesswork out of the equation.

One of the best reasons to upgrade now is the availability of government and utility rebates that can significantly reduce your out-of-pocket costs. Ontario homeowners may be eligible for rebates through programs such as the Enbridge Home Efficiency Rebate and other provincial incentive programs.

At Constant Home Comfort, we handle all the paperwork for you. Our team identifies every rebate you qualify for and applies them directly to your installation — so you save money without the headache of navigating government programs on your own.

We've been helping Ontario homeowners upgrade to smarter, more efficient home comfort systems for years. When you choose Constant Home Comfort for your tankless water heater installation, you get:

• Certified HVAC technicians with hands-on experience installing Rinnai, Navien, and other leading tankless brands
• Upfront, transparent pricing with no hidden fees
• Rebate assistance — we handle all program applications on your behalf
• Flexible 0% financing options, O.A.C. — get your upgrade with $0 down
• 24/7 service and repairs across the GTA, Hamilton, Ottawa, London, Waterloo, Barrie, and beyond
• Disposal of your old water tank and cancellation of your existing rental contract — handled by us

How long does it take for hot water to arrive from a tankless heater?

Most tankless units deliver hot water within 5 to 15 seconds of turning on the tap — similar to a traditional tank. The exact time depends on how far the unit is from your fixture and the pipe size. Some high-efficiency models include built-in recirculation pumps that reduce wait times even further.

Can a tankless water heater run out of hot water?

No — as long as the unit is properly sized for your home. A correctly sized tankless heater will never run out of hot water because it heats continuously on demand. It's only when a unit is undersized for a household's peak demand that you might notice a drop in temperature.

What maintenance does a tankless water heater require?

Tankless heaters require periodic descaling (flushing with a mild acid solution to remove mineral buildup), especially in areas with hard water. Annual or bi-annual maintenance keeps your unit running at peak efficiency and extends its lifespan. Our maintenance plans take care of this for you.

How much does tankless water heater installation cost in Ontario?

Costs vary depending on the model selected, your existing setup, and whether venting or gas line modifications are needed. In Ontario, a typical supply-and-install package ranges from $2,400 to $3,600 before rebates. With available government and utility rebates applied — which Constant Home Comfort handles on your behalf — your net cost can be significantly lower. Contact us for a free, no-obligation quote tailored to your home.

Stop paying to heat water you're not using. A tankless water heater from Constant Home Comfort gives your family unlimited hot water, lower energy bills, and peace of mind — all backed by expert installation and real rebate savings.

Call us anytime at 1-888-675-5907 or request a free quote online. Our HVAC specialists serve Toronto, the GTA, Hamilton, Ottawa, London, Waterloo, Barrie, and all of Ontario — 24/7.