| Business | Phone |
| G & O Thermal Supply Co 5435 N Northwest Hwy, Chicago 60630 | (773) 763-1300 |
| Control Solutions Intl 815 W Van Buren St 210, Chicago 60607 | (312) 829-3400 |
| South Side Control Supply Co 488 N Milwaukee Ave, Chicago 60610 | (312) 226-4900 |
| Simco Co 5040 N Mulligan Ave, Chicago 60630 | (773) 763-1297 |