Furnace Installation & Replacement

When a new furnace makes sense

Most furnaces in the Hamilton area are replaced for one of three reasons: the old one failed in a way that is not worth repairing, it has passed 15 to 20 years and is starting to break down every winter, or the owner is renovating, adding air conditioning or a heat pump, and wants the system matched. A furnace replacement in Hamilton is a big purchase, usually somewhere between $4,500 and $8,000 for a standard high-efficiency model, so it is worth doing once and doing properly.

Getting the size right

The single most common mistake is sizing the new furnace off the old one. Many furnaces installed in the 1980s and 1990s were oversized from the start, and the house has often been improved since: new windows, attic insulation, a better front door. An oversized furnace heats in short, loud bursts, leaves rooms uneven and wears out faster.

The proper method is a heat-loss calculation under CSA F280, the standard the Ontario Building Code points to for new systems. The contractor measures rooms, windows, walls and insulation and works out how much heat the house loses on a design day, about −18 °C in Hamilton. Our furnace and AC size calculator gives you a ballpark first, and the guide to what size furnace you need explains the numbers.

Efficiency and the choices that matter

Every new gas furnace sold in Canada must reach at least 95% annual fuel utilization efficiency (AFUE), so the difference between brands is less about burning gas and more about how the furnace moves air and adjusts its output.

• Single-stage: the burner is either fully on or off. Cheapest, and fine in a small, tight house.
• Two-stage: runs on a low fire most of the time and switches to high on cold days. Quieter, more even heat.
• Modulating: adjusts the flame in small steps to match the heat loss. The most comfortable and the most expensive.
• Variable-speed blower (ECM): uses far less electricity than an old blower and runs quietly at low speed, which helps air cleaning and pairs well with a heat pump.

Brand matters less than the installer. A mid-range furnace installed carefully, with the gas pressure set, the temperature rise checked and the ducts suited to it, will outlast a premium one put in badly.

What the installation involves

1. A home visit to measure the house, look at the ductwork, venting and gas line, and do the heat-loss calculation.
2. A written quote with model numbers, what is included and the warranty terms.
3. On the day, usually one day: the old furnace is disconnected and removed, the new one set in place, and the plenums and ducts connected.
4. New PVC venting to the outside, a condensate drain, and the gas connection by a certified gas technician.
5. Start-up, combustion and gas-pressure checks, and the thermostat set up.
6. Registration of the warranty with the manufacturer, which many brands require within 60 to 90 days.

Replacing an old mid-efficiency furnace that vented up a chimney with a water heater sometimes leaves the water heater alone in a chimney that is now too big for it. A chimney liner or a power-vented water heater fixes that, and a good quote mentions it.

Permits and rules

All gas work must be done by a TSSA-certified gas technician working for a TSSA-registered contractor. A straight furnace swap in an existing house does not usually need a municipal building permit in Hamilton, but new gas lines, moved or new ductwork in a renovation, and work in a new addition can. The contractor should tell you which applies and look after it.

Buy, finance or rent

Ontario has a large furnace and water heater rental market. Renting spreads the cost and usually includes repairs, but over a 10- to 15-year term the total is often double the purchase price, and buying out the contract early can be expensive. Since 2018, Ontario has banned door-to-door sales of furnaces, air conditioners and water heaters, so be wary of anyone who knocks unasked. Our guide to renting or buying a furnace or water heater works through the numbers.

How the request works

You request a furnace quote once, and we pass it to one licensed contractor who works your area. They book a visit, size the house and quote. If you are also thinking about cooling, ask for a heat pump option at the same visit: it can replace the air conditioner and take over much of the heating.