Venting
Safe operation of indirect-fired gas furnaces requires a properly operating
vent system which vents all the products of combustion (flue gases) to
the outside atmosphere.
EM Series duct furnaces are listed for Category II or IV vents
. Category II furnaces
operate with a negative vent pressure and Category IV furnaces operate with a positive
vent pressure. Vent gas temperatures are typically less than 150
o
F.
The vent piping must be exclusive to a single furnace and induced draft fan.
Common vent headers may not be used.
The venting system must be gas tight and water tight.
Use Schedule 40 PVC pipe or vent pipe listed to UL 1738
.
In Canada, the vent pipe
must be approved to ULC S636.
When using PVC pipe for venting,
sections must be solvent welded (glued)
consistent with industry standards and applicable local codes.
Primer and cement
for joints must conform to applicable ASTM standards.
Proper installation of the vent system must also assure drainage of condensate to
prevent deterioration of the vent system.
Do not use dampers in vent pipes.
All pipe openings external to building must have a protective screen installed.
