Two end markets, one industry

On 29 July, Lennox International — which sells furnaces, air conditioners and heat pumps to American homeowners through a distribution network, alongside light-commercial rooftop equipment — told investors that the replacement wave it had expected in the back half of this year would not arrive until 2027. Management blamed affordability, elevated mortgage rates and weak consumer confidence. Residential revenue fell 7% in the June quarter, and unit volumes fell 12%. New-construction revenue dropped about 30% after the company declined low-margin work. Full-year adjusted earnings guidance came down to $23-$24 a share, and the shares fell about 19% that day.

That is not a company-specific accident. American residential cooling demand is running below the natural replacement rate — roughly 7.5m units against the 8m implied by replacing 130m installed systems every sixteen years — and the distributors' trade association expects only 2-4% volume growth this year. Lennox's own commercial division, meanwhile, grew 24% and had its guidance raised to about 20%.

A day later Trane Technologies, the Irish-domiciled maker of chillers, air handlers and building controls that also owns the Thermo King truck and container refrigeration business, reported organic bookings up 37% and a record $12.1bn backlog, up 70%, with about $6bn of it scheduled for 2027 and later. Bookings for applied systems — the large engineered chiller plants a data center needs — more than doubled for a fourth consecutive quarter, rising 130%. Four individual orders exceeded $100m.

The margin nobody expected

AAON, the Tulsa manufacturer whose BasX division builds purpose-built data-center cooling and pre-packaged outdoor mechanical rooms alongside its legacy rooftop units, is the name most often described as the small-cap way to own this build. Its June quarter was extraordinary: revenue doubled to $627m, BasX-branded sales rose 216% to $345m, and backlog reached $2.0bn, up 98%.

Gross margin nonetheless fell 230 basis points to 24.3%, a fourth straight quarterly decline from 34.9% two years ago, and full-year gross-margin guidance was cut 200 basis points to 25-26%. Part of the reason is the ramp of a new Memphis plant, which absorbed $18.1m of overhead against $3m a year earlier. But management also attributed the compression to faster BasX growth carrying lower margins than the Oklahoma rooftop business. The engineered data-center dollar dilutes the mix rather than enriching it — the reverse of the case usually made for it. Backlog also slipped sequentially from $2.13bn. The competitive backdrop explains the pricing: in liquid cooling no vendor is dominant, with Vertiv leading at just over 11% and the top five holding about 35%.

Three declines, three causes

Between 22 July and 21 August, AAON fell 25.9% and Lennox 24.4% while Trane lost only 4.3% and the broad market rose. Lennox's entire move was two sessions around its guidance cut. AAON's came in three legs: a 20.8% slide before it had reported anything, alongside Vertiv's 17% drop on a revenue miss; 8.8% on its own results day; and 8.9% in the week the 30-year Treasury yield hit 5.33%, a 19-year high, which marks down every long-dated equipment backlog. Trane had recovered its post-earnings dip in full by 5 August.

Over twelve months the split is by end market, not by product. Vertiv is up 105%, nVent 76% and Modine 45%; Lennox is down 29%, Watsco 22% and Carrier 7%. AAON's remaining non-residential market is genuinely shrinking: non-residential construction spending fell 7% in nominal dollars over the first five months of the year.

What the prices now assume

AAON trades at 13.2 times trailing gross profit, against roughly 26 times in late May and 22 times in February — gross profit grew 28% over that stretch while the shares fell. That is now level with Trane's 12.7 times, a multiple unchanged since May, despite AAON growing many times faster; AAON's free cash flow is negative, at -1.8% of market value on $102.6m of capital spending so far this year. Trane converts at 3.8%. Lennox, at 7.9 times trailing gross profit and 17.0 times forward earnings, is the cheapest of the three on every measure, and its 5.3% free-cash-flow yield is the highest — the price of a business waiting on the homeowner.

The setup

Where it stands — One industry, two end markets: commercial and data-center orders at records, residential volumes contracting, and the shares punished together. Would confirm — AAON's September-quarter gross margin lands inside the new 25-26% guidance while BasX backlog resumes sequential growth. Would invalidate — Trane's applied bookings growth falls below 100% year on year, ending four straight quarters above it. Watch next — Lennox's third-quarter report in late October, the first test of the $23-$24 full-year earnings guidance. Valuation — AAON 13.2x trailing and 11.1x forward gross profit versus about 26x in May; Trane 12.7x; Lennox 7.9x.