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.
Search form. Plenum Heater. An electric plenum heater can convert your existing natural gas, propane, or oil furnace into a dual fuel heating system. An electric plenum heater gives you the ability to take advantage of the low-cost dual fuel electric rate and the flexibility to use the most cost-effective heating source at any time.