The burner fires directly in the air stream being heated, rather than through a heat exchanger. 100% of available BTUs are delivered to the heated space because no flue or heat exchanger is required. This results in no wasted energy.
Direct lighting
Light which shines directly onto a surface without intervening reflection between the light source and the surface.
Direct nailing
Nails that are hammered at right angles (perpendicular) to the work surface. Also called face nailing.
Direct overhead
Cost of doing business that is related on one specific job.
Direct reduction mortgage (drm)
A fully amortized mortgage necessitating periodic payments of both interest and principal. In the early years of the loan, he share of principal is smaller and the interest larger. This gradually reverses toward the end of the period.
Direct steam system
Heating system dependent upon radiators in each room of a structure. The steam goes from the boiler through pipes to the radiators with a two-pipe system being better for larger structures.
Direct tap
Clamping device, which when used on a main service line, allows a branch line to be drilled and tapped off. A connection can be made to a main line, without taking the main line out of service, by using this drill and tap to cut into the line and then installment of a corporation stop in the tapped hole, which provides control of the flow of fluid.
Direct vent
A system that pulls outside air for combustion and vents combustion gases directly outside without using a chimney.
Direct vent heater
A type of combustion heating system in which combustion air is drawn directly from outside and the products of combustion are vented directly outside. These features are beneficial in tight, energy-efficient homes because they will not depressurize a home and cause air infiltration, and backdrafting of other combustion appliances.
Direct water heater
A type of water heater in which heated water is stored within the tank. Hot water is released from the top of the tank when a hot water faucet is turned. This water is replaced with cold water that flows into the tank and down to just above the bottom plate under which are the burners.
