| Scot Pumps | Dockendorf, W.G., Inc. |
| Scott Springfield - Custom AHU | Engineered Comfort Systems |
| Seasons 4 - Rooftop Multizone Units | Engineered Comfort Systems |
| Seiho Int'l. - Round Registers | Stark, Carroll G. & Associates |
| Seismic Restraint Systems | DB Sales & Service |
| Semco Sound Traps/Panels | Conditioning Components Co. |
| Single-Stage Steam and Hot Water Absorption Chillers | York International Corp. |
| Sisco Pressure/Temp Valves | JD Sales Co., Inc. |
| Slant Fin - Finned Tube Radiation, Baseboard Radiation, Cast Iron Boilers | Dawson Co. |
| Smoke Detectors (System Sensor) | Airelink Products Corporation |
| Sound Testing | American Air Balance Co., Inc. |
| Sound Traps & Acoustical Sound Plenums (Rink) | Airelink Products Corporation |
| Sound Traps (Vibro-Acoustics) | Air Treatment Corp. |
| Square "D" Component Starters, Controls & VFD's | Marley Cooling Tower Company |
| Standard Fin Pipe | JD Sales Co., Inc. |
| Steam Boilers | DB Sales & Service |
| Sterling Gas Furnace | Haldeman, Inc. |
| STERLING/ALTON - Evaporative Coolers, Make-Up Air Units, VAV Roof Top Units | Louis Horsefield & Associates |
| STERNVENT - Dust & Oil Mist Collecting Equipment | Louis Horsefield & Associates |
| Strobic - Tri-Stack Air Systems | DMG Corporation |
| SUN MANUFACTURING - Wall Hung Air Conditioning | Southern Ca A/C Distributors |
| Supply Items (Sheet Metal, Sealants, Tape, Screws) | Airelink Products Corporation |