| Plumbers PIPE Fitters and MES | Related tax-exempt org | Share of e | OH | 310561070 |
| Investment Trust Local 392 | Related tax-exempt org | Lease | OH | 237166422 |
| Plumbers PIPE Fitters & MES | Related tax-exempt org | Expenses | OH | 310655223 |
| Plumbers Pipefitters & MES | Related tax-exempt org | School | OH | 310619811 |
| Mechanical Contractors Association | Related tax-exempt org | Associatio | OH | 310249290 |
| Plumbers PIPE Fitters & MES Local | Related tax-exempt org | Union | OH | 310474230 |
| Plumbers Pipefitters & MES Local 3 | Related tax-exempt org | DRUG testi | OH | 311370066 |
| Plumbers Pipefitters & MES Local | Related tax-exempt org | Support | OH | 900058137 |
| OHIO State Association of Plumbers | Related tax-exempt org | Reciprocit | OH | 340707601 |
| AC&R Specialists | Related taxable corporation/trust | Contractor | IA | 421064284 |
| Advanced Facilities | Related taxable corporation/trust | Contractor | OH | 311475939 |
| Advanced Mechanical of N KY | Related taxable corporation/trust | Contractor | KY | 812647078 |
| Alpha Mechanical Service | Related taxable corporation/trust | Contractor | KY | 510456396 |
| Artic Heating A& AC INC | Related taxable corporation/trust | Contractor | OH | 311002682 |
| B&B Mechanical Services INC | Related taxable corporation/trust | Contractor | OH | — |
| Bachmans INC | Related taxable corporation/trust | Contractor | OH | 310580562 |
| BMWC Constructors INC | Related taxable corporation/trust | Contractor | IN | — |
| Bodie Mechanical Services INC | Related taxable corporation/trust | Contractor | OH | — |
| Bowen Engineering Corporation | Related taxable corporation/trust | Contractor | IN | — |
| C&D Mechanical | Related taxable corporation/trust | Contractor | OH | 311099535 |
| Carrier Corporation | Related taxable corporation/trust | Contractor | NY | 060991716 |
| Clays Performance Construction | Related taxable corporation/trust | Contractor | WV | 472231636 |
| Climate PROS | Related taxable corporation/trust | Contractor | OH | 550914273 |
| Coenen Mechanical | Related taxable corporation/trust | Contractor | WI | — |
| CR Meyer & SONS | Related taxable corporation/trust | Contractor | MI | — |