Tankless Water Heater Installation in Ottawa
On-demand hot water, sized for Ottawa's coldest incoming water, not a sunny spec sheet
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On-demand hot water, sized for Ottawa’s coldest incoming water, not a sunny spec sheet
- Free quotes on any equipment purchase
- Financing from $49/month (OAC)
- All makes and models serviced
How a tankless water heater works, and why sizing is everything
A tankless water heater has no storage tank. When you open a hot tap, a flow sensor fires a gas burner and water is heated as it passes through a heat exchanger, so you get hot water for as long as you need it, with no standby loss.
The trade-off is that a tankless unit can only heat so many litres per minute. Undersize it and the water turns lukewarm the moment a second shower starts. That is why every tankless water heater Oria installs in Ottawa is sized for winter, not summer.
Most modern units are condensing, with efficiency in the mid-90s, and they vent through PVC pipe like a high-efficiency furnace. With regular descaling, many last 20 years, roughly twice as long as a typical hot water tank.
Sizing a tankless water heater for Ottawa’s cold water
Start by adding up the fixtures that could run at the same time, then check what the heater can deliver at your coldest incoming water temperature. In Ottawa that is about 2–5 °C in winter, and you want roughly 49 °C at the tap, a rise of about 45 °C.
| Fixture | Typical flow |
|---|---|
| Low-flow shower | 1.5–2.0 GPM |
| Kitchen or bathroom faucet | 1.0–1.5 GPM |
| Dishwasher | 1.0–1.5 GPM |
| Washing machine (hot fill) | 1.5–2.0 GPM |
Here is roughly what common gas unit sizes deliver. Exact figures vary by model, so we confirm with the manufacturer’s flow chart before quoting.
| Gas input | Approx. flow in winter (about 45 °C rise) | Approx. flow in summer (about 35 °C rise) |
|---|---|---|
| 120,000 BTU/h | 2.5–3.0 GPM | 3.5–4.0 GPM |
| 160,000 BTU/h | 3.5–3.8 GPM | 4.5–5.0 GPM |
| 199,000 BTU/h | 4.5 GPM | 6.0 GPM |
Two showers and a dishwasher in January need about 5 GPM. That is beyond a single 199,000 BTU unit, so larger homes either stagger use or install two units linked together.
Is a tankless water heater right for your home?
Tankless is a great upgrade for many Ottawa homes, but not all of them. Here is how we help people decide.
Good fit: you run out of hot water
Families with teenagers or a big soaker tub get continuous hot water instead of a 40-gallon limit.
Good fit: you need the space
A wall-hung unit frees up the floor space a tank uses, handy in finished basements and utility rooms.
Good fit: you plan to stay
A 20-year lifespan rewards owners who will be in the home long enough to recover the higher upfront cost.
Think twice: a small gas line
A 199,000 BTU unit often needs a larger gas line. If the run is long or difficult, a high-efficiency tank may be better value.
Learn more →Think twice: very hard well water
Rural wells around Greely, Osgoode and Carp often scale heat exchangers quickly. A water softener or yearly descaling becomes essential.
Think twice: frequent power outages
Tankless units need electricity to run. A conventional gas tank still heats water when the power is out.
Combi units: heat and hot water from one appliance
A combi boiler is a wall-hung, high-efficiency boiler that heats your home through radiators or in-floor heating and also supplies on-demand domestic hot water. It is a popular choice for Ottawa homes with hydronic heat because it replaces both an old boiler and a tank with one compact unit.
There are also tankless combi systems paired with a hydronic air handler, which can heat a ducted home from the same unit that makes your hot water. These suit smaller, well-insulated homes where the heating load is modest.
Hot water usually gets priority, so the combi pauses space heating while a shower runs. Sizing has to cover both jobs at once. A high-efficiency combi or heating boiler typically costs $7,000 to $15,000 installed; see our boiler services for details.
Gas line, venting and electrical requirements
A tankless water heater asks a lot of your gas supply all at once. A 199,000 BTU unit draws more than most furnaces, and the existing half-inch line that fed a 40,000 BTU tank is often too small.
Gas piping
We calculate pipe size from the total load on your system and the length of the run, and upsize where needed. We also confirm the meter can carry the added load. See gas line installation.
Venting
Condensing units vent through PVC or polypropylene pipe out a side wall or roof, kept clear of windows, doors and where snow drifts in Ottawa winters.
Condensate
The unit produces a small amount of acidic water that needs a drain, often with a neutralizer.
Power
A standard 120 V outlet runs the controls and fan.
Getting these right is the difference between steady hot water and a unit that throws error codes every time the dryer and furnace are running.
Descaling and yearly maintenance
- 1
Isolate the heater
Gas and power are turned off, and the isolation valves on the hot and cold lines are closed.
- 2
Flush with descaler
A small pump circulates a descaling solution through the heat exchanger for about 45–60 minutes to dissolve mineral scale.
- 3
Clean the inlet filter
The screen on the cold-water inlet is removed, rinsed and reinstalled so flow is not restricted.
- 4
Check venting and condensate
We inspect the vent terminals, clear blockages and confirm the condensate line and neutralizer are draining freely.
- 5
Test and review error history
We relight, check temperature and combustion, and review stored error codes for early signs of trouble.
Tankless water heater cost in Ottawa
A tankless water heater typically costs $3,500 to $6,500 installed in Ottawa, before rebates. Where your job falls depends mainly on gas-line work, vent length and whether you want a recirculation pump for faster hot water at distant taps.
| Option | Typical range (CAD, before rebates) |
|---|---|
| Tankless water heater, installed | $3,500 – $6,500 |
| Gas tank water heater, 40–50 gallon, installed | $1,800 – $3,200 |
| High-efficiency combi boiler, installed | $7,000 – $15,000 |
The final price depends on the home, equipment and venting. Oria gives free quotes on any equipment purchase, and financing from $49/month is available on approved credit.
Rebates may be available for qualifying high-efficiency units. Oria will check current programs for your home; see HVAC rebates. For a deeper side-by-side, read tank vs tankless water heater.
Licensed gas technicians for your tankless upgrade
- TSSA and HRAI approved
- 5.0 stars from 578 Google reviews
- Free quotes on any equipment purchase
- Financing from $49/month on approved credit
Frequently Asked Questions
Straight answers from licensed Ottawa technicians. Still have a question? Call us any time.
How many showers can a tankless water heater run in an Ottawa winter?
A 199,000 BTU gas tankless water heater delivers about 4.5 gallons per minute when incoming water is 2–5 °C, which is enough for two low-flow showers, or one shower plus a dishwasher. Three showers at once in January usually need two units linked together or a staggered routine.
How much does a tankless water heater cost in Ottawa?
A tankless water heater typically costs $3,500 to $6,500 installed in Ottawa, before rebates. Gas-line upsizing, long vent runs and a recirculation pump move the price toward the top of the range. The final price depends on your home and equipment, and Oria Heating and Cooling gives free quotes on any equipment purchase.
Does a tankless water heater work during a power outage?
No. A gas tankless water heater needs electricity for its controls, igniter and fan, so it stops making hot water when the power is out. If outages are common where you live, a conventional atmospheric gas tank, which needs no power, may be a better fit.
How often should a tankless water heater be descaled in Ottawa?
Homes on Ottawa city water, which comes from the Ottawa River and is relatively soft, can usually descale every one to two years. Homes on well water in rural areas such as Greely, Richmond or Carp often have hard water and should descale every year, or install a water softener.
Can a tankless water heater use my existing gas line?
Sometimes, but often not. A typical tank uses about 40,000 BTU per hour, while a large tankless unit can draw 199,000 BTU per hour. Pipe size depends on the total load in the house and the length of the run, so a licensed gas technician should calculate it before installation.
How long do tankless water heaters last?
With regular descaling and annual service, many gas tankless water heaters last around 20 years, about twice as long as a typical gas tank. Scale buildup from hard water is the main thing that shortens their life, so maintenance matters more than with a tank.
What is a combi boiler?
A combi boiler is a single wall-hung, high-efficiency boiler that heats your home through radiators or in-floor heating and also provides on-demand hot water. It replaces both a heating boiler and a hot water tank. In Ottawa, a high-efficiency combi boiler typically costs $7,000 to $15,000 installed.
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