CECO Environmental (CECO) 8-K/A Financial Statements and Exhibits

Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We have issued our reports dated August 31, 2015 with respect to the consolidated financial statements and internal control over financial reporting of PMFG, Inc. and subsidiaries incorporated by reference in this Current Report of CECO Environmental Corp. onForm 8-K. We hereby consent to the incorporation by reference of said reports in the Registration Statements of CECO Environmental Corp. on Forms S-3 (File No.333-130294, FileNo. 333-142052, and FileNo. 333-183275), onForms S-8 (FileNo. 333-33270, FileNo. 333-143527, FileNo. 333-159948, FileNo. 333-200000, and FileNo. 333-206743), and onForms S-4 (FileNo. 333-204816 and FileNo. 333-188797).

/s/ GRANT THORNTON LLP

Dallas, Texas

November 17, 2015