Indirect-fired heaters have some significant differences from their direct-fired counterparts. Instead of the air coming into direct contact with the flame, these heaters use a combustion chamber ...

the fuel will not contact the valve, thus causing carbon deposits to build up on the valve face. A direct injection engine can be costly to maintain when compared to basic indirect systems.

For many years ecologists have sought to understand the roles and importance of direct and indirect effects in communities. Direct effects, as the name implies, deal with the direct impact of one ...