Short version: a new gas furnace installed in the Ottawa Valley costs about $3,500 to $8,000 in 2026, and most homeowners land between $4,500 and $6,000. The spread is wide because your house, not the furnace sticker, decides the number.
The 2026 quick answer
Entry high-efficiency swap: $3,500 to $5,000. Mid-range two-stage: $5,000 to $7,000. Premium modulating (the quiet, even-heat kind): $6,000 to $8,000+. Add-ons and any duct or venting changes sit on top of that.
Every “average furnace cost” article gives you a number that is almost certainly wrong for your home. A 1,100 square foot bungalow in Carleton Place and a drafty century home in Perth do not get the same furnace, the same install, or the same invoice. Below is exactly what goes into the number, cost by home size, and how to tell when it is time to replace, so you can walk into a quote knowing what you are looking at.
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What is the average cost of a new furnace in 2026?
Across the Ottawa Valley, a new high-efficiency gas furnace runs about $3,500 to $8,000 installed, with most homeowners paying $4,500 to $6,000. Where you land inside that range comes down to the size and efficiency of the furnace and how much work your install actually needs. An entry-level high-efficiency swap sits near the bottom, a premium modulating system near the top.
What factors affect furnace cost?
A furnace quote is not one number, it is a stack of them. Here is everything that goes into your price, and why each one changes what you pay. This is also the honest answer to “why is furnace installation so expensive?”, you are paying for the right-sized equipment and the labour to install it safely, not just the box.
What size furnace do I need?
Bigger home, more heat needed, bigger furnace. Ottawa Valley homes typically need somewhere between 40,000 and 120,000 BTUs of output, and the size you need is usually the single biggest lever on your price. Here is a rough guide by home size, though your insulation, ceiling height and window quality all shift it:
| Home size | Typical furnace output | Typical installed cost |
|---|---|---|
| Up to 1,200 sq ft | 40,000 to 60,000 BTU | $3,500 to $5,000 |
| 1,200 to 2,000 sq ft | 60,000 to 80,000 BTU | $4,500 to $6,000 |
| 2,000 to 3,000 sq ft | 80,000 to 100,000 BTU | $5,500 to $7,000 |
| 3,000+ sq ft | 100,000 to 125,000 BTU | $6,500 to $8,000+ |
Guide only. Proper sizing is done with a heat-loss calculation during your in-home assessment, not off square footage alone.
Furnace efficiency and staging: single-stage vs two-stage vs modulating
This is the comfort dial. A single-stage furnace is either full blast or off. A two-stage runs low most of the time and kicks to high on the coldest days, which means fewer temperature swings and quieter operation. A modulating furnace fine-tunes itself constantly for the most even heat and the lowest running cost. Comfort and quiet go up as you move up the ladder, and so does the price, roughly $500 to $1,000 per step.
Your home’s age and insulation
Two homes the same size do not always need the same furnace. A newer, well insulated build holds heat, so it can run a smaller, cheaper unit. A 100 year old farmhouse near Almonte with original windows leaks heat, needs more output, and pushes the price up. Newer efficiency also opens the door to a smaller modulating furnace that sips gas, which can be worth the higher upfront cost.
Venting
High-efficiency furnaces vent out the side wall through plastic pipe, not up an old chimney. If your current setup already uses White PVC or Black ABS venting, a swap is straightforward. If we have to change how your furnace vents, that adds a few hundred dollars.
Is it a straight replacement?
A “straight replacement,” same location, same ductwork, same gas and electrical, is the cleanest and cheapest install. The moment we have to modify ductwork, move the unit, upgrade a gas line, or add electrical, the labour climbs. Duct changes alone can run anywhere from $300 to $2,000 depending on what your home needs.
How much do furnace add-ons cost?
A furnace is the heart of the system, but most homeowners add one or two upgrades while the tech is already there. It is far cheaper to do it now than to call someone back later. These are the common ones and what they run:
| Upgrade | What it does | Added cost |
|---|---|---|
| Ecobee smart thermostat | Learns your schedule, cuts heating bills, controls from your phone | +$565 |
| Whole-home humidifier | Kills the winter dry air that cracks skin, floors and furniture | +$895 |
| 5″ media filter cabinet | Traps far more dust and allergens than a 1″ filter, lasts a year | +$465 |
| UV / air quality upgrade | Neutralizes mould, bacteria and odours moving through your ducts | +$795 |
Prices shown are current Comfort Pro add-on pricing and are confirmed on your final estimate.
Are there furnace rebates in Ontario in 2026?
Here is the honest part most furnace ads leave out. In 2026, the big government grants are aimed at heat pumps and insulation, not at swapping one gas furnace for another. If you are replacing a gas furnace with a gas furnace, you usually will not see the headline $5,000 numbers you read about. There are still smaller utility incentives that come and go, and if a heat pump makes sense for your home the rebate math changes a lot. The cleanest move: get your furnace number first, then ask us what you actually qualify for. We will tell you straight, no rebate fairy tales.
Should you repair or replace your furnace?
If your furnace is under about 12 years old and the repair is small, fixing it is usually the right call. Once it is past 15 years, breaking down often, or the repair bill starts creeping toward half the cost of a new unit, replacement is the smarter money. Most gas furnaces last 15 to 20 years, less if they were oversized or poorly maintained.
Signs you can still repair
- Under 12 years old
- First real breakdown
- Repair is a few hundred dollars
- Heats evenly and bills are steady
Signs it is time to replace
- 15+ years old
- Rising gas bills for the same comfort
- Frequent repairs, or one big one
- Cold spots, short cycling, or strange noises
What does a furnace cost for a typical Ottawa Valley home?
To put the range in context: a well insulated 2,000 square foot bungalow on a straight replacement, natural gas, existing side-wall venting, typically lands around $5,000 to $5,800 for a high-efficiency unit before any add-ons. Move to a premium modulating furnace, or add a humidifier and a better filter, and the number climbs from there. Drop to a smaller, tighter home and it comes down. That is why the only price that matters is the one built for your home.
Why “average cost” is useless for your house
You have now seen why the range is so wide. Size, age, efficiency, staging, venting and add-ons can swing the same job by thousands of dollars. A national average tells you nothing about your basement. The only way to get a real number is to have someone look at your actual setup, which is exactly what our free in-home assessment does. No pressure, no obligation.
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Furnace cost FAQ
How much does it cost to replace a furnace in the Ottawa Valley?
Most gas furnace installs run $3,500 to $8,000, with the majority of homeowners paying $4,500 to $6,000. Your final price depends on the size of your home, the efficiency and staging of the furnace, your venting, and any duct or add-on work.
Why is furnace installation so expensive?
You are paying for two things: the right-sized, high-efficiency equipment, and the licensed labour to install it safely and to code. Venting changes, duct work, gas and electrical connections, permits and removal of the old unit all sit inside that price.
What size furnace do I need?
Ottawa Valley homes usually need 40,000 to 120,000 BTUs. The right size depends on your square footage, home type, age and insulation, which is why we size it with a heat-loss calculation during a free in-home assessment rather than guessing off square footage alone.
How long does a furnace last?
Most gas furnaces last 15 to 20 years. Regular maintenance stretches that; an oversized or neglected furnace falls short of it.
Should I replace a 20-year-old furnace?
Usually yes. Past 15 years a furnace is running less efficiently and is more likely to fail in a cold snap. If it is 20 and needing repairs, putting money into a new high-efficiency unit almost always beats patching the old one.
How long does it take to install a new furnace?
A straight replacement is typically a one-day job, often four to eight hours. Installs that need duct or venting changes can take longer.
Is a high-efficiency furnace worth it?
For our winters, yes. High-efficiency furnaces (95% AFUE and up) turn far more of your gas into heat and are the standard for new installs. Stepping up to two-stage or modulating adds comfort and quiet, and can lower running costs over the life of the unit.
Do furnace rebates still exist in Ontario?
The largest grants now target heat pumps and insulation, not gas furnace swaps. Smaller utility incentives come and go. Ask us and we will tell you exactly what you qualify for today.
Can I finance a new furnace?
Yes. Financing spreads the cost into manageable monthly payments so a breakdown does not have to be a one-time hit. Ask us about current options when you book your assessment.
How do I get an exact price?
Call Comfort Pro at 613-253-4277 to book a free in-home assessment and we will price it for your home.