How Long Does a Furnace Installation Take in Ontario?

Most like-for-like furnace replacements take between four and eight hours to complete, meaning your old furnace can be swapped out for a new one all within the same day. More involved furnace installations, however, may take longer, especially when the project requires significant changes to the ductwork, venting, electrical wiring or gas lines.

Because every home and heating system is different, your contractor can provide a more accurate estimate based on the installation area, the condition of your existing infrastructure and the work involved. Here's what Ontario homeowners need to know about installing a new furnace.

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A standard furnace installation generally takes between four and eight hours when the new furnace is replacing an existing furnace of a similar model. That said, installation times can vary depending on your home and current heating system.

For example, if your home has never had a furnace (e.g., replacing a wood-burning stove) or the new unit requires a different setup, the technicians may need to install or modify some necessary components or complete a heat-loss calculation based on your home and local winter conditions to determine the appropriate furnace size.

The following table can give you a rough idea of a timeline for installing a new furnace:

Disclaimer: These timeframes are general estimates. The installation duration can vary depending on your furnace type, the condition of the existing system and any issues found after the old unit is removed.

While the exact process will depend on your furnace and home, most installations follow the same general stages. Here is what you can expect, as well as a rough approximation of how long each stage will take, once the technicians arrive:

1. Arrival and walkthrough (~15 to 30 minutes)

The installation team will inspect the installation site and check the walking path through your home to make sure they can move both furnaces in and out safely. They will then get their tools ready and likely put down floor coverings to protect your floors.

2. Removing the old furnace (~60 to 90 minutes)

They will shut down the old furnace and disconnect it from the home's electrical system, thermostat, venting, ductwork, and fuel supply. Next, they will remove the unit from the home and get the space ready for the new furnace. If your home has narrow stairs, crawl spaces and/or a smaller or tight mechanical room, it may take the technicians a bit longer at this stage.

3. Placing the new furnace (~60 to 120 minutes)

They will move the new furnace into place and make sure it's both positioned and levelled correctly before being connected to the supply and return ductwork. Should the new unit have different dimensions from the previous one, nearby duct sections may need to be adjusted or custom transition pieces may be required.

4. Completing the connections (~60 to 120 minutes)

For a gas furnace, the technician will connect the gas line and then check it for any leaks. They will also install or reconnect the venting, condensate drain, electrical wiring, and thermostat. If they are replacing an older furnace with a high-efficiency model, it may take them longer at this stage if the venting setup needs to change.

5. Testing the furnace (~45 to 90 minutes)

Once the furnace is connected, the technicians will turn it on and check that it is operating properly. This may include testing the gas pressure, airflow, temperature change, venting and thermostat. This way they can then make any necessary adjustments based on the manufacturer’s instructions and your home’s ductwork.

6. Cleanup and walkthrough (~20 to 40 minutes)

Lastly, the technicians will clean up the work area and remove the old equipment. Afterward, they will show you how to use the new furnace and thermostat, and explain where the filter is located, which size you need and when to replace it.

Yes, many HVAC companies can complete a standard furnace replacement within one day, especially when it's a straightforward replacement. However, a more complex installation may affect your expected timeline when the project involves one or more of the following:

Various factors that can affect the installation time

• Homes with narrow stairs, crawl spaces, tight doorways or mechanical rooms

• Larger homes with more complex duct systems

• If you want or need to relocate the furnace to another area of the home

• Installing or modifying ductwork, venting, drainage, electrical or fuel connections

• Adding or upgrading equipment, such as a humidifier, thermostat or air conditioner

• Condo access requirements

• Municipal inspection requirements or permits (where applicable)

• ESA notification or inspection requirements (where applicable)

• Discovering unknown issues after removing the old furnace

A few simple preparations can help support a more efficient installation process by allowing the technicians to get started on time and move the old and new equipment through your home more easily. Here’s what you can do before they arrive:

• Clear boxes, furniture and stored items away from the furnace.

• Make sure the electrical panel is easy to access.

• Leave an open path between the entrance and the mechanical room.

• Move vehicles away from the equipment unloading area.

• Keep pets and children away from the work area.

• Confirm parking, elevator and loading arrangements if you live in a condo.

• Have your Wi-Fi password available if a smart thermostat is being installed.

Your new furnace may need a few days of regular use before you have a clear sense of how well it is heating your home. During that time, pay attention to how the system starts, how air moves through the rooms and whether the temperature feels consistent throughout the house.

Here are a few things you should check after installation:

Scheduling a home assessment gives your contractor a chance to look at your home's existing ductwork, venting, gas lines, and electrical connections ahead of time so they can provide a more accurate estimate. That way, you can plan ahead for installation day and already know what to expect as your old furnace is replaced with a new heating system.

Book a home assessment and request a furnace installation quote.