I'm looking at a gas heater it is vented this the description would comments good or bad,,,,thanks

"This is a counter flow heater, which means it has a fan at the top that blows the cool room air down over the heating surfaces and out the bottom of the unit. The unit is thermostatically controlled and includes the thermostat. The heater also includes the vent cap which mounts through the wall back of the heater to provide fresh air for the combustion and an exhust. "