Venting And Chimney Requirements - Williams 4505622A Owner's Manual

Installing Your Furnace

Venting and Chimney Requirements

Proper venting of this furnace is required to prevent the release of
hazardous gases into the dwelling. The furnace must always be
vented into a vertical vent. This vent may be a listed type "B" gas
vent or lined masonry chimney. The following statements are
intended as a guide for venting the furnace. If other venting
requirements are required by local codes, the local codes must be
adhered to.
If the furnace is to be vented into a masonry chimney, be sure the
chimney is lined, clean and in good repair. Be sure the vent
system is installed by a qualified installer and -
1. Do not connect this furnace to a chimney flue serving a
separate solid fuel (coal or wood) burning appliance. Soot and
creosote deposits from the solid fuel heating appliance can
block the vent serving this furnace.
2. If this furnace is to be connected to a chimney that has
previously been used for a solid fuel appliance, clean the
chimney thoroughly of all deposits that might drop down and
block the furnace vent.
3. The total length of the horizontal run of vent connector pipe
must not exceed 75 percent of the height of the gas vent or
chimney above the point where the vent connector is
attached. All venting material must be supported by hangers
spaced a maximum of four (4) feet apart and attached to the
floor joist or by other methods approved by local codes.
4. The horizontal vent connector must be not less than 4 inches
in diameter.
5. The horizontal vent connector must slope upward from the
furnace to the chimney at least 1/4 inch per foot of connector
length.
6. Avoid using a vent or chimney for more than one furnace if it is
practical, but if it is necessary to use one vent for two
furnaces, be sure the vent or chimney has an interior liner at
least 6 inches in diameter.
7. If two furnaces are connected to a chimney or vent with a
common vent connector, join the unit connectors as shown in
Figure 3. Do not join the vent connectors with a tee. Be sure
to size the vent connectors as shown in Figure 3.
8. Use a thimble when attaching the vent connector to a lined
masonry chimney, and place the thimble at least 6 inches
above the bottom of the chimney. Seal the vent connector and
thimble joint to prevent gases from escaping.
9. Keep the vent connector at least 6 inches from all combustible
material and if the vent connector must pass through a
partition constructed of combustible materials, use a thimble in
the partition that has been listed for this use by a nationally
recognized testing agency. An improperly installed vent
connector can overheat adjacent materials and cause a
dangerous fire.
10. Be sure that there are no unsealed openings in the vent or
chimney that will decrease the chimney draft and the chimney
is at least 2 feet higher than all parts of the building within 10
feet. This is required to reduce the possibility of wind
interfering with the draft (see Figure 4).
11. If the furnace is to be vented into a masonry chimney, be sure
the chimney is lined, clean and in good repair.
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12. Never terminate a vent pipe inside an attic, under the building,
in a closet or with a horizontal run of vent pipe. The vent pipe
must extend above the roof of the building as shown in Figure
4.
FIGURE 3 Unit Connector
FIGURE 4 Chimney Height
13. Do not use an uninsulated vent pipe. An uninsulated vent pipe
can cause a fire hazard by overheating adjacent combustible
materials. An uninsulated vent pipe can also cause
condensation of the vent gases within the pipe and retard the
draft.