Direct Vent Fireplaces
Direct vent is a sealed, specially designed gas venting
system which provides all of the combustion air to the appliance from
outside the house through one pipe and which discharges combustion by-products
to the outside through another pipe. Providing outside combustion air
as part of the venting system and sealing out contact between the combustion
process and the dwelling are the distinguishing characteristics of direct
vent technology. Because they do not interact with the indoor environment,
direct vent systems are less likely to be affected by normal negative
pressure situations in a house.
Coaxial Direct Vent Systems
Coaxial systems use a pipe inside a larger pipe. The smaller
pipe is centered and fixed in position with spacers in the larger pipe.
Combustion products exit through the smaller inner pipe. Outdoor combustion
air flows in through the space between the two pipe. Coaxial systems
may be rigid or flexible.
Colinear DV Systems
Colinear systems use two separate pipes, which are usually
flexible pipes. One pipe, usually smaller, brings in outdoor combustion
air. The other, usually larger, pipe handles combustion products. The
pipes may be the same size, so it is important to make sure the pipes
are used and installed correctly.
Manufacturer's instructions may call for the exhaust pipe
to be insulated and maintain minimum clearances to combustibles.
