80% vs 96% Efficiency Furnace
A 96% furnace burns gas 16% more efficiently than an 80% — but the install is more involved (PVC venting, condensate drain). Does the upgrade actually pay back?
80% AFUE
Standard-efficiency, metal-vented furnace
- Lower install cost — uses existing chimney/B-vent
- Simpler install — no condensate drain required
- Best fit when replacing an old 80% in a non-condensing flue setup
- 16% more gas burned for same heat output
- No federal tax credit eligibility
- Out of code in some jurisdictions for new construction (Utah still allows replacement)
Replacement-only in older homes where reusing existing flue makes the math work, very mild-use homes, tight-budget jobs.
96% AFUE
High-efficiency, condensing furnace with PVC venting
- 16% less gas use → $200-$400/year savings in typical Utah home
- PVC sidewall venting (no chimney needed) — more flexible install
- Lower flue temps, safer combustion
- Eligible for some utility rebates
- Higher install cost — typically $1,500-$2,500 more upfront
- Condensate drain required — minor freeze-risk in unconditioned spaces
- Slightly more service complexity (inducer motor, pressure switches, condensate pump)
New installs, homes with high gas bills, anyone staying 10+ years, replacing in spring/summer when comfort-of-replacement isn't urgent.
Our Recommendation
For a Utah home using $1,200-$1,800/year in gas, the 96% pays back in 4-7 years. If you're staying 10+ years, the 96% wins every time. The exception: replacing an 80% in a chimney-vented setup where the rest of the house relies on that chimney (water heater B-vent draft) — orphaning the water heater on a too-large chimney creates condensation problems. We size both options at the in-home visit.
Still on the fence?
Free in-home estimates with both/all options quoted side-by-side. No pressure, no obligation — just the numbers for your home.
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