Single stage, efficient gas furnaces typi.y cost $, or higher, moving up to a efficiency range of this same type can cost $,. To move into the efficiency range with a multi stage or modulating furnace that feature variable s.d blowers can cost $, to $,..The national average cost of furnace replacement is $,, with most homeowners spending between $, and $,. This data is based on actual project costs as reported by HomeAdvisor members. Whether you need to replace a dead furnace or install an entirely new heating system, you’re lo.ng at a significant investment..The cost to Install a Gas Furnace starts at $, $, per furnace, but can vary significantly with site conditions and options. Get fair costs for your SPECIFIC project requirements. See typical tasks and time to install a gas furnace, along with per unit costs and material requirements..Typical costs Replacing a gas furnace can cost $ $, for a self contained and vented wall unit that provides air directly to the surrounding Replacing an oil fired furnace in a central heating system starts typi.y costs $, $, for a basic installation, but can reach .