When replacement may make more sense than another repair
A heat exchanger concern is often the clearest case — it's generally treated as a safety issue, and on an older, out-of-warranty furnace the cost of repair may not be worth it. Beyond that, it often comes down to the numbers: if a repair estimate is a large fraction of the cost of a new system, or if the furnace has needed multiple repairs in recent winters, replacement is worth discussing with a local HVAC professional.
If none of that applies, repair may be the more practical option — a local HVAC professional can help you weigh it.
Sizing: bigger isn't always better
Many Colorado homes built before the 1990s have furnaces sized for a leakier house than the one that's there today. Newer windows, added insulation and air sealing can all lower the amount of heat a home actually needs. A local HVAC professional can help figure out appropriate sizing for your specific home rather than just matching the old unit.
A properly sized furnace commonly runs longer, gentler cycles, which many homeowners notice as steadier temperatures throughout the house and less noise.
Choosing an efficiency level
80% AFUE
Generally lower equipment and installation cost, and often vents through an existing metal flue. This can make sense when a condensing furnace's venting requirements would be costly to add, or in a home you don't plan to keep long term.
90–98% AFUE (condensing)
Extracts more heat from the exhaust and typically vents through PVC, requiring a condensate drain. Installation costs are often higher, but many homeowners see it pay off over time through lower gas usage across Colorado's long heating season.
Single-stage, two-stage and modulating
Single-stage furnaces run at full output or not at all. Two-stage units run at reduced capacity most of the time and full capacity on the coldest days. Modulating furnaces adjust more gradually. Many homeowners find two-stage and modulating furnaces quieter and better at evening out temperatures across a two-story home — a common reason people decide to upgrade.
Questions worth asking about the installation
- How will the new furnace be sized for your home?
- What does the venting and combustion air setup look like for the new equipment?
- Will gas piping be checked for capacity?
- Is a condensate drain needed for a condensing furnace, and how will it be handled?
- Will ductwork be adapted to fit the new equipment?
- What's included in the written quote, and what isn't?
- What permitting and inspection steps are involved?
Comparing quotes fairly
Ask each professional for model numbers, AFUE rating, staging type, blower type, and a line-item scope of work. A higher quote that includes more thorough venting or duct work may be the better value over the life of the system. Ask what is not included — that's often where the difference between two quotes shows up.