The American black bear lived during the same period as short-faced bears (Arctodus simus and A. pristinus) and the Florida spectacled bear (Tremarctos floridanus). These Tremarctine bears evolved from bears that had emigrated from Asia to North America 7â8 ma.
A plenum space is a part of a building that can facilitate air circulation for heating and air conditioning systems, by providing pathways for either heated/conditioned or return airflows, usually at greater than atmospheric pressure.
The Master Flow Duct Board Plenum attaches to the furnace supply or return. It provides a box to create duct runs. The insulation board reduces ventilation system noise and condensation for improved system performance. Seals the underside of the floor joist space to create a duct run to channel air back through the air return system. 2  16in. width is equal to the distance of joist spacing, which enables the panning to be nailed or screwed directly into the wood.