Furnace System GuideCarrier and Lennox both sell premium high-efficiency furnaces near the top of the AFUE range. This page collects the specs each brand publishes on its own site, brand by brand, then notes where they differ on paper. It does not pick a winner.
How to Read This Comparison
Every spec below is taken from each manufacturer's own furnace pages, and each brand describes its lineup differently, so direct one-to-one matching is imperfect. AFUE figures are the top-of-line numbers a brand advertises as up to a certain percentage, which a given installed model may or may not hit.
AFUE measures fuel-to-heat efficiency only. It does not capture install quality, duct losses, dealer network, or price, all of which matter in a real purchase. Treat this as a paper-spec reference, not a verdict.
Where a brand did not publish a number on the page reviewed, this comparison leaves it out rather than estimating it.
Carrier, As Published
Carrier positions the Infinity 98 Gas Furnace, model 59MN7, as its most advanced, energy-efficient furnace. Carrier states the Infinity 98 uses modulating operation that adjusts heat in 1 percent increments, paired with variable-speed blower motors.
On efficiency, Carrier's furnace page states that Comfort Series furnaces can provide energy savings with AFUE ratings of up to 95 percent. Carrier's lineup steps down from the modulating Infinity 98 to two-stage and single-stage models.
These are the figures Carrier publishes on its furnace overview page as of this review.
Lennox, As Published
Lennox tops its lineup with the SLP99V Variable-Capacity Gas Furnace from the Dave Lennox Signature Collection, which Lennox advertises at up to 99.0 AFUE. That is the highest published AFUE figure among the major residential brands reviewed here.
Lennox states that its SilentComfort technology uses variable-speed technology, which ramps up gradually and eliminates the sudden kick or blast of air upon startup. Below the variable-capacity SLP99V, Lennox lists two-stage models and single-stage models.
These are the figures Lennox publishes on its furnace pages as of this review.
Where They Differ on Paper
On advertised top-tier AFUE, the published numbers differ. Carrier cites AFUE ratings of up to 95 percent for its Comfort Series, while Lennox cites up to 99.0 for its variable-capacity SLP99V flagship. Both brands top their lineups with fine burner control and a variable-speed blower.
Both also offer stepped-down two-stage and single-stage models beneath the flagship, so the structure of each lineup is similar even where the exact numbers differ. Carrier highlights modulation in 1 percent increments, while Lennox highlights a variable-capacity design and a blower that eliminates the startup blast.
The specs published on each brand's page do not settle which furnace is better for a given home. Price, the local dealer, install quality, and warranty registration all sit outside these numbers.