CECO vs DCI: Which Is the Better Buy in 2026?

Same yardstick, side by side (as of November 2026). Valuation lined up like this is most meaningful for two names in the same corner of the market, which these are. Figures are approximate; verify before investing.

The metrics above tell you which is the marginally better business. The bigger risk for most people is not picking the slightly worse stock, it is over-concentrating. CECO and DCI share themes, so owning both, or adding either to what you already hold, can quietly push a large share of your portfolio into one bet.

This is the part a generic comparison page cannot answer, because it depends on what you own. Connect your brokerage and Walnut shows your real, combined CECO and DCI exposure, flags overlap with your existing positions, and tells you if adding one would tip you past a concentration you are comfortable with, read-only by default, with your login staying at your broker. Walnut is not an investment adviser.

CECO Environmental was incorporated in 1966 and now runs out of Addison, Texas, just outside Dallas. It sells engineered equipment that cleans, moves, separates, quiets and heats industrial process streams: selective catalytic reduction systems and gas turbine inlet and exhaust packages for power plants, cyclones and dust collectors for cement and metals, thermal oxidizers and scrubbers for chemicals, filtration and fluid handling for semiconductors and food processing, and acoustic enclosures where noise limits are part of the permit. The business is reported in two segments, Engineered Systems and Industrial Process Solutions. On June 1, 2026 CECO closed a roughly $2.2 billion combination with Thermon Group, a maker of electric and steam heat tracing, controllers, boilers and thermal fluid heaters, adding a business with roughly $520 million of annual revenue, gross margins near 45 percent and a large recurring maintenance component. CECO shareholders own about 62.5 percent of the combined company. In October 2026 CECO announced it would transfer its primary listing from the Nasdaq Global Select Market to the Texas Stock Exchange, with Nasdaq trading expected to end October 16 and TXSE trading to begin October 19, 2026; the ticker and CUSIP stay the same.

Full CECO guide

Donaldson Company, Inc. (NYSE: DCI) makes filtration systems and, more importantly, the replacement filters that go into them. Three segments carry the business: Mobile Solutions, the largest at roughly ~62% of fiscal 2025 sales, covering air and liquid filters plus emissions systems for off-road machinery, trucks and the independent aftermarket; Industrial Solutions, covering dust collection, compressed air, gas turbine intake and, since May 2026, jet fuel filtration through the acquired Facet business; and Life Sciences, a smaller unit spanning food and beverage process filtration, disk-drive filters and an assembled bioprocessing portfolio built from Solaris, Purilogics, Isolere Bio and Univercells Technologies. Filters are consumable and often regulated, so a machine sold once generates parts revenue for a decade or more.

Full DCI guide

Both fit overlapping themes, but they are not interchangeable. The useful comparison is which set of drivers and risks you want exposure to.

• CECO drivers: Natural gas power and the data center buildout; Thermon and the shift toward recurring revenue.
• DCI drivers: Replacement filters as the recurring base; Facet and a heavier aerospace, defense and power tilt.

A faster-growing, richer-valued name usually swings harder, so it suits a longer horizon and a higher tolerance for volatility; a steadier, more cash-generative business suits a more conservative or income-minded investor. The honest test is which set of risks you could hold through a drawdown: Project revenue is lumpy, and a book to bill above two in one quarter does not repeat forever. For DCI, mobile Solutions ties a majority of revenue to off-road and on-road equipment cycles, so agriculture, construction and truck build rates set the direction of first-fit volumes regardless of how steady the aftermarket is.

Growth-minded investors who believe the theme has years to run tend to accept the richer multiple for more upside; value-minded investors lean toward the cheaper forward earnings and steadier profile. Pick CECO if you believe its drivers more; DCI if you believe its. Many investors hold both, but since they share themes, that is a concentrated bet, not diversification. Decide deliberately and check overlap. For the full detail, see the CECO and DCI guides.

CECO. The trailing numbers and the forward numbers describe two different companies, because Thermon only joined on June 1, 2026 and the 2026 guide carries seven months of it. That gap is why trailing GAAP earnings are negative while the forward multiple of about 19 times 2027 consensus EPS looks like an ordinary growth industrial. Anyone reading CECO on trailing figures alone will misprice it in one direction, and anyone reading it purely on guidance assumes the synergy and conversion plan lands; the third quarter report, expected around October 27, 2026 with consensus near $400 million of revenue and $0.59 of EPS, is the first full quarter with Thermon.

DCI. At about ~18x forward earnings Donaldson trades below the ~23x it fetched on forward estimates in August 2026, after a post-earnings slide left the shares down about 2.4% for the year. Trailing free cash flow of ~$322 million is lower than in prior years as Facet debt and capital spending absorb cash, so the case leans on fiscal 2027 margin guidance of ~16.6% to ~17.2% holding.

Headline figures (approximate, October 2026): CECO shows revenue (ttm) ~$903M; Q2 2026 ~$285M, up ~54%, fy2026 guidance (with thermon) Revenue ~$1.300B to ~$1.375B, adjusted EBITDA ~$200M to ~$225M, q2 2026 orders and backlog Orders ~$799M (up ~191%), backlog ~$1.82B (up ~164%), q2 2026 margins and eps Adjusted EBITDA margin ~14.1%, adjusted EPS $0.47 vs ~$0.33 estimate; DCI shows revenue (fy2026, ended jul 31, 2026) ~$3.89B, a record (~+5% vs FY2025), q4 fy2026 sales / adjusted eps ~$1.06B (+~8% YoY) / ~$1.15 vs ~$1.13 expected, margins (ttm) Gross ~35%, operating ~17%, net ~11.7%, net income / eps (fy2026) ~$454M / ~$3.85.

CECO and DCI are related but distinct: same themes, different businesses and risks. Neither wins in the abstract; the right pick is whichever thesis you actually believe, sized so you are not over-concentrated in one theme. Walnut can show your combined CECO and DCI exposure against your real portfolio. It is not an investment adviser.