With a high grade at the back of the house where the mechanical equipment sits, we were unable to use a wooden rim joist, so we actually need to core our mechanical penetrations through solid concrete.
The concrete coring work is commonly done for plumbing work and of course enlarging basement windows. The holes I needed were more like 3 inches diameter, so they go pretty quick. Having a water injection system on a powerful drill with long bits makes the job possible. I like to use the guys from ABC coring. They once again proved themselves to be excellent operators.
A bunch of holes are cut through the concrete wall, these are for furnace intake and exhaust, gas line, and electrical conduit for the panel service and communication wires.