Most people ask about price when the furnace has already stopped, it is cold out and they want to know how bad the news is going to be. That is a fair question, and it deserves a straight answer, even if it is not a single number. What a furnace repair or a new furnace costs depends on what failed, how old the system is and, in Waterdown, which era of house it is sitting in. This guide walks through what actually goes into the price, so you can read a quote and know whether it makes sense.
What's the average cost to fix a furnace?
There isn't a useful average, because furnace repairs range from a part that fits in your palm to a fault that takes the whole unit out of service. An average blends a quick igniter swap with a heat exchanger replacement and tells you nothing about your own furnace. What you can know is the list of things every repair price is built from:
- The diagnosis. A technician has to test the system to find the fault, not guess at it. On a modern furnace that means checking the igniter, flame sensor, pressure switches, inducer, limit switches, control board and the venting.
- The part. Small wear parts such as igniters and flame sensors sit at the low end. Motors and control boards cost more, and some parts are specific to one model.
- The labour. Some parts come out in minutes. Others mean taking apart half the cabinet.
- Access. A furnace tucked behind a finished basement wall or in a tight crawl space takes longer to work on than one in an open utility room.
- Timing. If a part has to be ordered, there may be a second visit to fit it.
When someone gives you a figure on the phone without seeing the furnace, it is a guess. A proper price comes after the fault is found, and you should see it in writing before anything is replaced.
What is the most expensive part to fix on a furnace?
The heat exchanger is usually the biggest repair on a gas furnace. It is the metal chamber that keeps the flame and its exhaust separate from the air blown through your house. When it cracks, combustion gases, including carbon monoxide, can get into that air. Replacing one means taking the furnace apart, and on an older unit the part may cost a large share of a new furnace, if it is still available at all.
A cracked heat exchanger is a safety fault, not a comfort fault. If a technician finds one, the furnace should be shut off until it is dealt with. Make sure you have a working carbon monoxide alarm next to each sleeping area; the Ontario Fire Code requires one in any home with a fuel-burning appliance, a fireplace or an attached garage.
After the heat exchanger, the larger repairs tend to be:
- The control board, the furnace's small computer, which can fail after a power surge or simply with age.
- The inducer motor, which pulls exhaust through the vent pipe. When it gets noisy or slow, the furnace often shuts itself off.
- The blower motor, especially variable-speed motors in newer high-efficiency furnaces.
If the furnace is still under the manufacturer's parts warranty, some of these parts may be covered, though labour usually is not. Keep the registration and your maintenance records handy, because manufacturers can ask for both.
How much does a new furnace cost for a 2000 sq ft house?
Square footage is where most people start, and it is one of the least reliable ways to price a furnace. Two houses of the same size can need quite different equipment. A furnace is sized to how much heat the house loses on a cold day, and that depends on insulation, windows, air leakage, ceiling height and which way the house faces. With January normals around -4.7 °C at the Hamilton RBG station near Waterdown and a long heating season after that, getting the size right matters for comfort and for how long the furnace lasts.
The things that move the price of a replacement are:
- The size and type of furnace. A properly sized unit, worked out with a heat-loss calculation, is often smaller than the one it replaces.
- Efficiency and features. A single-stage furnace costs less up front than a two-stage or modulating one with a variable-speed blower, which runs quieter and evens out temperatures.
- The ductwork. A new furnace has to move air through the ducts you already have. If they are undersized, the furnace runs loud and wears out early, and some duct changes may belong in the price.
- The venting. High-efficiency furnaces vent through plastic pipe, usually out a side wall. Where that pipe runs, and what happens to anything left in the old chimney, can add work.
- The gas line, electrical and condensate drain connections.
- Permits and the removal of the old unit.
Gas appliances in Ontario have to be installed to the CSA B149.1 installation code by a TSSA-registered contractor, under Ontario Regulation 212/01. That is not a place to save money, because a poor installation can also affect the manufacturer's warranty. It is also worth checking whether any current rebate programs apply before you choose equipment.
How does the age of your house change the price?
In Waterdown, the era of the house tells a technician a lot before the cabinet is even opened.
- Older houses in the Griffin Survey and the McMonnies and Stock Survey were built before the Second World War, often for coal or wood, then converted to oil and later gas. They can have converted ductwork and unlined masonry chimneys. When a new high-efficiency furnace stops venting into that chimney, condensation from whatever is left venting into it can damage the masonry, so a chimney liner may need to be part of the job.
- Post-war and later surveys such as Glenlea, Buchan Court and Renwood Park usually have forced-air systems, many first fired by oil. The common surprises here are original ductwork that is too small for a modern furnace, and a gas water heater left alone in an oversized chimney after the furnace is moved to a side-wall vent. That water heater can backdraft, so the venting has to be sorted out as part of the replacement.
- Newer homes in Waterdown South and Waterdown Bay already have high-efficiency furnaces, side-wall venting and HRVs, so replacement is often more straightforward. Repairs in these houses tend to centre on condensate drains, pressure switches and blocked vents.
What should a written price include?
A good quote is specific enough that you could compare it fairly with another one. Look for:
- The exact fault found, or the exact equipment proposed, including size and efficiency.
- What is included: removal of the old unit, venting, chimney work, duct changes, permits, thermostat.
- What is not included, and what would change the price.
- The manufacturer's warranty terms and whether the equipment needs to be registered.
If the technician recommends replacement over repair, ask for both prices side by side. A young furnace with a small fault is usually worth fixing. An old furnace facing a heat exchanger or a second major part in a short time is often better replaced, and seeing both numbers makes that decision yours.
Can you avoid a repair call altogether?
Sometimes. Before you call, check that the furnace switch is on, the filter is not clogged and the thermostat has batteries and is set to heat. After a storm, look at the plastic vent pipes on the side of the house; snow drifts can bury them and the furnace will shut itself off. Clear them by hand and restart the furnace. If you smell gas, leave the house and call the gas utility from outside. Regular maintenance also catches worn parts before they fail on the coldest night of the year.
If your furnace is acting up, our furnace repair page explains how a visit works, and Work is performed by TSSA-certified gas technicians.