Furnace System GuideTrane and Lennox both sell premium high-efficiency furnaces. 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.
AFUE measures fuel-to-heat efficiency only. It does not capture install quality, duct losses, dealer network, or price. 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.
Trane, As Published
Trane's top furnace is a 96 Modulating Variable Speed Gas Furnace, which Trane states has an AFUE of up to 97.3 percent and is its most efficient furnace. Trane lists single-stage and two-stage models below the modulating flagship.
On its furnace pages, Trane also states the efficiency tiers it works within: the government's minimum standard is 80 AFUE, and a furnace with an AFUE of 90 or higher qualifies as high efficiency. Trane adds that, when well-maintained, a Trane furnace can last 20 or more years.
These are the figures Trane publishes on its furnace pages 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. 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 flagship, Lennox lists two-stage models and single-stage models, so the lineup steps down in the same tiered pattern as other major brands.
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. Trane cites up to 97.3 percent for its 96 Modulating Variable Speed flagship, while Lennox cites up to 99.0 for its variable-capacity SLP99V. Both brands pair fine burner control with a variable-speed blower at the top of the range.
Both lineups step down to two-stage and single-stage models, so the overall structure is similar. Trane highlights a 20-plus-year lifespan with maintenance, while Lennox highlights a blower that eliminates the startup blast.
The published specs 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.