Tankless Heater
Tankless Water Heater Installation in Ontario
Getting Sizing Right
A tankless installation starts with counting how many fixtures might run at once in your home: a shower, a kitchen tap, a washing machine. That number, combined with your incoming water temperature, determines the unit's required capacity. Undersize it and you'll be disappointed every time two things run together; oversize it and you've paid for flow you'll never use. The unit is sized for realistic simultaneous demand, not an idealized endless supply.
Beyond sizing, a proper installation means confirming the gas line can deliver enough fuel at the unit's maximum firing rate, routing venting to the correct termination clearances, and setting up the condensate drain if the model is condensing. Older homes often need a larger gas line run from the meter, and that work has to happen before the heater itself goes in.
Service Inclusions
- ✓ Gas line sizing
- ✓ Venting
- ✓ Tank to tankless conversion
- ✓ Startup test
Typical price range
$3,500 to $6,500
Typical Ontario price range before tax. Your actual price depends on your equipment, parts and access, and is confirmed after we assess the job.
Get a tailored estimate →Reasons Homeowners Switch
Existing Tank Nearing End Of Life
A tank water heater over ten years old with rust spots or rumbling is a common trigger for homeowners considering the switch to tankless.
Running Out Of Hot Water Often
A tank that can't keep up with back to back showers is a sign a correctly sized tankless unit could better match your household's pattern.
Wanting To Reclaim Floor Space
A wall mounted tankless unit frees up the footprint a bulky tank occupies, which matters in tight mechanical rooms and condos.
Gas Line Already Undersized
Homes with older, smaller gas piping may need upgraded line sizing before a tankless unit can fire at its rated capacity.
Our Installation Process
- 01
We review your fixture count
Typical simultaneous use and incoming water temperature to recommend a unit sized for real demand, not a marketing number.
- 02
Existing gas supply
Existing gas supply and venting routes are checked against the new unit's requirements, with any upgrades scoped and priced before installation day.
- 03
The unit is mounted
Connected to gas, water and venting, and the condensate line is set up if the model requires one for drainage.
- 04
Once running, we test at multiple flow rates, confirm stable temperature
And walk you through the controls, filter location and maintenance schedule.
What Affects Price
Unit Size And Features
Larger capacity units and models with recirculation or smart controls cost more than a basic single bathroom unit sized for lighter demand.
Gas Line Upgrades
If your existing gas line is undersized for the new unit's firing rate, running a larger line adds to the overall installation cost.
Venting Complexity
Venting through an exterior wall is usually simpler and less costly than routing through multiple floors or finished spaces.
A tankless unit sized and connected correctly delivers steady temperature at realistic household flow for years, while an undersized or poorly vented installation leads to constant frustration and callbacks. HeatNest technicians size the unit to your actual fixtures, verify gas and venting capacity before installing, and test at real world flow rates before calling the job done.
Gas Safety During Installation
Any gas appliance installation involves live gas connections, and a leak during or after installation is not something to wait out. If you ever smell gas or a carbon monoxide alarm goes off near a newly installed unit, leave the house, call 911 or your gas utility from outside, and don't attempt to inspect the connection yourself. Proper installation includes a pressure test, but ongoing vigilance afterward still matters.
Before You Book
Be specific about every fixture that might run at
Once in your home so the sizing recommendation reflects your actual household, not a general estimate.
If you're also adding a gas range
Or fireplace later, mention it now so the gas line sizing accounts for combined future demand.
Gas line and appliance installation in Ontario requires a licensed gas technician
So confirm that credential as part of choosing any contractor.
Why Homeowners Choose HeatNest
HeatNest installs tankless systems from multiple manufacturers and treats sizing as the most important step in the whole job, not an afterthought. We'd rather tell you a unit won't meet your simultaneous demand before installation than have you discover it the first busy morning.
Accurate Sizing
We size for your realistic simultaneous fixture use, not a generic household average that may not match your actual habits.
Licensed Gas Work
Confirm that the person responsible for gas connections holds the appropriate current Ontario qualification. The quoted work should identify required tests, venting materials and any approvals for your particular installation.
Full Startup Testing
Every installation is tested at multiple flow rates before we leave, confirming the unit performs the way it was sized to.
Brands We Install
Common Questions
+How do I know what size tankless water heater I need?
Sizing depends on how many fixtures might realistically run at once in your home and your incoming water temperature, which a technician calculates during the assessment visit.
+Will a tankless water heater give me truly endless hot water?
It gives continuous hot water as long as demand stays within its rated simultaneous flow; exceeding that limit still drops temperature, just like any sized appliance.
+Do I need to upgrade my gas line for a tankless unit?
Possibly. Tankless units often require more gas flow than a tank, so we check your existing line against the new unit's firing rate before installation.
+Can a tankless heater be installed in the same spot as my old tank?
Often yes, though venting requirements differ, so the location is confirmed against clearance and termination rules before the swap, not assumed automatically.
+What should I do if I smell gas after a new installation?
Leave the home immediately, call 911 or your gas utility from outside, and do not attempt to check the connection yourself while gas may be present.
+How soon can HeatNest install a new tankless water heater?
Timing depends on unit availability and any required gas or venting work, so we'll give you a realistic schedule during the assessment rather than a guaranteed same day promise.
Where We Work
HeatNest installs tankless water heaters across Ontario, serving homeowners in Toronto, the surrounding GTA and nearby communities who want sizing and gas work handled by a licensed technician.
Acton · Adjala Tosorontio · Ailsa Craig · Ajax · Angus · Arva · Aurora · Aylmer · Ayr · Barrie · Bolton · Bowmanville · Bradford · Brampton · Brantford · Brooklin · Burford · Burlington · Caledon · Cambridge · Clarington · Collingwood · Courtice · Delaware · Dorchester · Dutton · East Gwillimbury · East York · Enniskillen · Erin · Etobicoke · Exeter · Fort Erie · Georgetown · Georgina · Glencoe · Grimsby · Guelph · Halton Hills · Hamilton · Hensall · Ilderton · Ingersoll · Innisfil · Keswick · Kilworth · King City · Kitchener · Komoka · Lincoln · London · Lucan · Markham · Midland · Milton · Mississauga · Mitchell · Mitchell Corners · Mono · Mount Brydges · New Tecumseth · Newcastle · Newmarket · Niagara Falls · Niagara on the Lake · Nobleton · North York · Norwich · Oakville · Orangeville · Orillia · Oro Medonte · Orono · Oshawa · Ottawa · Parkhill · Pelham · Pickering · Port Colborne · Port Stanley · Puslinch · Richmond Hill · Scarborough · Schomberg · Scugog · Shedden · Smithville · Springwater · St. Catharines · St. Marys · St. Thomas · Stratford · Strathroy · Sutton · Thamesford · Thorndale · Thornhill · Thorold · Tillsonburg · Toronto · Tottenham · Tyrone · Unionville · Uxbridge · Vaughan · Wasaga Beach · Waterloo · Welland · Whitby · Whitchurch Stouffville · Woodstock
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What customers say about our tankless water heater installation
"Called in the morning, had someone here by mid afternoon. Friendly, careful and professional from start to finish."
"Great communication, I got a heads up before arrival and a clear summary of the work afterwards."
"The technician showed up on time, explained exactly what was wrong and had everything working the same afternoon. No upselling, just honest work."
Ready To Plan Your Installation
Considering a tankless water heater or replacing a worn out tank? Call HeatNest at (289) 801-7262 to book a sizing assessment and get an honest recommendation for your home.