Tankless Water Heater Installation in Ottawa: What Homeowners Need to Know Before Making the Switch

Endless hot water, a smaller footprint and no bulky tank in the corner of your basement — it's easy to see why so many homeowners ask us about tankless water heater installation in Ottawa. But going tankless is not a simple swap. The right result depends on proper sizing, an adequate gas supply, correct venting and a clean, code-compliant install.

This guide from the team at KAD Mechanical & HVAC walks you through what to expect, what affects the job, and how to know whether a tankless water heater is a good fit for your home.

How a Tankless Water Heater Works

A tankless (on-demand) water heater has no storage tank. When you open a hot tap, the unit senses the water flow and fires a powerful gas burner. Water passes through a heat exchanger and comes out hot within seconds. When the tap closes, the burner shuts off.

Because nothing is being kept hot around the clock, there is no standby heat loss like you get with a traditional tank. Most whole-home tankless units installed in Ottawa today are high-efficiency condensing models that vent through PVC pipe.

The trade-off: flow rate

A tankless heater never "runs out" of hot water, but it can only heat so many litres per minute. If too many fixtures run at once — say two showers and the dishwasher — the unit can struggle to keep up. That's why sizing is the most important part of the job.

Is Tankless Water Heater Installation in Ottawa Right for Your Home?

Tankless is a great choice for many households, but not all. It tends to suit you well if:

• Your family often runs out of hot water with your current tank.
• You want to free up floor space in a finished or tight basement.
• You plan to stay in the home long enough to benefit from the longer service life.
• Your current water heater is near the end of its life and you're replacing it anyway.

A conventional tank might still make more sense if your budget is tight, your gas supply would need major upgrades, or your hot water needs are small. If you're still weighing tank versus tankless, a technician can look at your home and explain the trade-offs honestly before you commit.

Sizing a Tankless Unit for Ottawa Winters

This is where many installs go wrong. In Ottawa, the water coming into your home from the city main or a well gets very cold in winter, when outdoor temperatures often drop below −25 °C. A tankless heater has to raise that icy water all the way up to shower temperature — and the bigger that temperature jump, the lower the flow rate the unit can deliver.

A unit that feels perfect in July can leave you with a lukewarm shower in January if it was sized only for average conditions. A proper sizing looks at:

• Peak demand: how many showers, taps and appliances might run at the same time.
• Winter inlet temperature: the coldest water the unit will realistically see.
• Fixture flow rates: rain shower heads and soaker tubs need much more hot water than standard fixtures.
• Household size and habits: back-to-back morning showers are very different from one person's evening routine.

We size every unit for the worst case, so you get steady hot water all year.

What Tankless Water Heater Installation Involves

A professional tankless water heater installation in Ottawa usually includes several steps beyond hanging the unit on the wall.

1. Gas line assessment and upgrade

Tankless units have a much higher gas input than most tank heaters. In many older homes — common in neighbourhoods like Westboro, Alta Vista and parts of Nepean — the existing gas line is too small to feed a tankless unit along with the furnace, stove and other appliances. Running a properly sized line is often part of the job. In Ontario, this work must be done by a TSSA-licensed gas technician.

2. Venting

Condensing tankless units vent through PVC piping, usually out a side wall or through the roof. Venting must meet clearances from windows, doors, decks, the gas meter and the ground, and should be positioned so snow drifts in an Ottawa winter don't block it.

3. Condensate drain

High-efficiency units produce acidic condensate that needs to be safely drained, often through a neutralizer to protect your plumbing.

4. Water connections and isolation valves

We install service valves so the unit can be descaled easily during future maintenance, plus any required pressure relief and backflow protection.

5. Removal of the old tank

Your old water heater is drained, disconnected and hauled away. If your existing tank is a rental, you'll need to contact the rental company about returning it — we can help you understand the process.

6. Testing and walkthrough

We check for gas leaks, verify combustion and venting, confirm temperature and flow at the fixtures, and show you how the unit works.

What Affects the Cost of Going Tankless

Every home is different, so costs vary. The main factors are:

• The size and model of the tankless unit.
• Whether your gas line needs to be upgraded or extended.
• How far the unit is from an exterior wall for venting.
• Condensate drain access.
• Any plumbing changes needed to relocate the water heater.

At KAD, we give you upfront pricing with no hidden fees before any work starts. The best way to get an accurate number is to request a free quote and have a technician look at your setup.

Energy Use and Your Enbridge Gas Bill

Because a tankless unit only burns gas when you're using hot water, many households see lower water-heating costs on their Enbridge Gas bill compared to keeping a tank hot 24 hours a day. How much you save depends on your usage, the efficiency of your old heater and how well the new unit is sized and maintained. We'd rather give you an honest picture than a sales pitch — for some low-use homes, the savings are modest.

Keeping Your Tankless Water Heater Running Well

Tankless water heaters can last longer than tank models, but only with care. Minerals in the water slowly build up inside the heat exchanger, reducing efficiency and eventually triggering error codes or shutdowns. Regular maintenance should include:

• Descaling (flushing) the heat exchanger.
• Cleaning the inlet water filter screen.
• Checking venting, the condensate line and burner operation.
• Inspecting gas connections for safety.

Our furnace and water heater maintenance visits can cover both appliances at once, which is convenient before winter.

Why Choose KAD for Tankless Water Heater Installation in Ottawa

KAD Mechanical & HVAC has served Ottawa homeowners for more than 10 years, with over 500 completed projects and a 98% customer satisfaction rate. Our certified, TSSA-licensed gas technicians handle the full job — sizing, gas line, venting and installation — so you deal with one team from start to finish.

We work across Ottawa, Kanata, Nepean, Barrhaven, Orleans and surrounding areas. You can see examples of our work in our project gallery, or learn more about our furnace and water heater installation services, including both tank and tankless options.

Ready to stop running out of hot water? Call us at (613) 790-2675 or book online, and we'll help you decide whether tankless is the right move for your home.

Frequently Asked Questions

Written by the KAD Mechanical & HVAC team

Certified, TSSA-licensed heating, water heater and gas technicians serving Ottawa, Kanata, Nepean, Barrhaven and Orleans for 10+ years.

Next article: Furnace Making Noise? What Banging, Squealing and Rattling Mean for Ottawa Homeowners