Water Heater Replacement Cost and Quotes, Ontario

What a new water heater costs in Ontario

Gas tank water heater, 40 to 50 gallons

$1,800 to $3,200

Gas tankless water heater

$3,500 to $6,000

Installed, before HST. Reviewed October 2026.

Leaking right now?

Close the cold water valve on the pipe at the top of the tank. On a gas tank, turn the gas control knob to Off. On an electric tank, switch off its breaker. Do not open the drain or touch the water if it is hot. Then send a request and choose Urgent. If you smell gas, leave the house and contact your gas utility's emergency line from outside.

Those ranges cover a standard swap: the heater, connections, suitable venting, removal of the old unit and labour. A tank swap often takes half a day, a first tankless install a full day. Water heater requests follow the same steps shown on the FurnaceQuotes.ca home page: a booking call, an in-home visit, then a written quote.

What moves the price

Tank to tankless
New venting, a bigger gas line and wall mounting. Most of the price gap lives here.
Gas supply
A tank burns roughly 30,000 to 50,000 BTU/h. Many tankless units burn up to 199,000 BTU/h and need a larger gas line ($300 to $1,200).
Access and code updates
A tight closet or a new location adds time, and an expansion tank or new valves may be needed.

Tank or tankless: which should you quote?

For most homes, another gas tank is the lowest-cost fix. Tankless suits households that run out of hot water or plan to stay long enough to recover the higher price.

Gas tank, 40 to 50 gal

Upfront: $1,800 to $3,200 installed.
Venting: the chimney, or a fan-driven vent out a side wall.
Hot water: runs out, then needs time to reheat.
Life: about 8 to 12 years. Drain the sediment yearly.

Gas tankless

Upfront: $3,500 to $6,000 installed.
Venting and gas: new side-wall venting, often a larger gas line.
Hot water: endless, up to its flow rate at one time.
Life: often 15 to 20 years. Descale yearly in hard water.

Add-ons on a tankless quote

Ask for each as its own line.

Gas piping: $300 to $1,200
Venting changes or a chimney liner: $300 to $1,500

Typical add-on prices in Ontario, before HST. Reviewed October 2026. Only some homes need each item.

Radiators or in-floor heat?

A combi boiler heats the house and your tap water in one wall-hung unit, typically $7,000 to $13,000 installed, replacing both the boiler and the water heater. See boiler and combi boiler quotes.

Size it right: first-hour rating and flow

Size a tank by your busiest hour. Size tankless by what runs at once on the coldest day of the year.

First-hour rating (FHR) is how many gallons a tank delivers in one busy hour. It depends on the burner as much as the tank, so compare FHRs. Rough guide: 40 gallons for one or two people, 40 to 50 with a good FHR for three or four, and a high-input tank or tankless for five or more.

Flow rate (GPM) sizes tankless. Ontario tap water can drop to about 5°C in winter, so the unit must heat it 44°C to reach 49°C. At that rise, a 199,000 BTU/h condensing unit gives about 4.8 GPM. Each 2 GPM shower draws about 1.6 GPM of hot water, so two showers and a tap fit, but three showers and the dishwasher do not.

Hot water sizing check

Winter flow for tankless and the first-hour rating for a tank, as a rule of thumb.

Assumes showers mixed to about 40°C, a dishwasher at 1 GPM, a warm wash at 1.5 GPM, a tap at 1 GPM, and one 199,000 BTU/h unit at 95% efficiency.

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Power vent or atmospheric?

The quote should say which type you are getting, and why.

Atmospheric

Exhaust rises up the chimney on its own. No fan and no power, so you keep hot water in an outage. It is the cheapest to install but needs a sound, properly sized chimney.

Power vent

A fan pushes exhaust through plastic pipe out a side wall. It needs an outlet, hums a little, costs more and stops in an outage, but frees you from the chimney.

Watch for an orphaned chimney

A new high-efficiency furnace with plastic venting can leave the water heater alone in a chimney sized for two. It may not draft properly and can need a liner ($300 to $1,500). If your furnace was replaced recently, ask about it.

Renting your water heater? Check the contract first

Rented tanks are common in Ontario. Before replacing one, find out what leaving costs and how the tank goes back.

Find the agreement
It lists the buyout schedule and any exit fees.
Get the buyout in writing
Buyouts usually drop as the tank ages. Ask how long the figure holds.
Ask about removal and return
Who takes the tank, any return fee, and when billing stops. Charges usually run until it is returned or bought out.
Compare the total
The rental you would keep paying, against buying a tank at $1,800 to $3,200.

Every $10 a month of rental adds up to $1,200 over ten years. See financing vs renting in Ontario.

Know your rights

Ontario bans most door-to-door water heater sales: a company cannot sign you up at home unless you contacted it first. Contracts signed at home usually have a 10-day cooling-off period.

What your water heater quote should list

A price and a brand are not enough to compare. Look for:

Brand, model number, size in gallons, input in BTU/h and efficiency (UEF)
First-hour rating for a tank, or winter flow rate for tankless
Venting type and route, plus any chimney liner
Gas line work, with the pipe size and a pressure test
An expansion tank if your water service has a check valve
Removal and disposal, or return of a rented tank
Any permit, and who gets it
Warranty years for the tank, parts and labour, listed separately
Price before HST, deposit, install date and how long it holds

Gas work in Ontario

In Ontario, only a TSSA-registered contractor, using certified gas technicians, may install or repair gas appliances. Ask for the company's TSSA registration number and the technician's certificate before work starts. We do not certify, license or inspect any company.

Have more than one quote? Line them up in the quote comparison worksheet, or test a price with the quote checker.

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Common questions

Straight answers. If yours is not here, the company can answer it during your free estimate.

How much does it cost to replace a hot water tank in Ontario?

A standard 40 to 50 gallon gas tank typically costs $1,800 to $3,200 installed, before HST. A power-vent model, a chimney liner, an expansion tank or a hard-to-reach spot pushes it higher. Tankless typically runs $3,500 to $6,000 because of new venting and gas work.

Water heater in Ontario: is renting or buying cheaper?

Over the life of a tank, buying usually costs less, because rental payments continue as long as you keep it. Renting spreads the cost and usually covers repairs. Multiply your monthly charge by the years you expect to stay and compare that with a purchase quote.

Can I get out of my water heater rental contract?

Usually, yes. Most rentals let you buy the tank out or return it, and the buyout often drops as the tank ages. Some contracts add removal or return fees, so get the buyout figure and the return steps in writing before booking.

Is a tankless water heater worth it for a family of four?

It can be if you often run out of hot water or plan to stay ten years or more. Size it for winter: one whole-home gas unit typically covers two showers and a tap at once, not three showers and a dishwasher. If upfront price matters most, choose a well-sized tank.

Who can install a gas water heater in Ontario?

Only a TSSA-registered contractor with certified gas technicians may do gas appliance work in Ontario. Ask for the registration number, and check the quote says who handles the gas line, venting and any permit. Be wary of a cash price with no paperwork.

Keep going

Get a written water heater quote

Tank or tankless, owned or rented now. Answer a few quick questions and a participating local company checks your venting and gas supply, then quotes it in writing.