SYSTEM OPERATION
16
NOTE:
The vertical height of the Category I venting system
must be at least as great as the horizontal length of the
venting system.
WARNING
To prevent possible death or personal injury due to asphyx
-
iation, common venting with other manufacturer’s induced
draft appliances is not allowed.
When an existing furnace is removed from a venting sys-
tem serving other appliances
, the venting system may be
too large to properly vent the remaining attached applianc-
es. For complete details refer to
Exisiting Furnace Removal
section of this manual.
When resizing any portion of the common venting system,
use the appropriate table in Appendix G in the latest edition
of the National Fuel Gas Code NFPA 54/ANSI Z223.1.
Upflow or Horizontal units
are shipped with the induced
draft blower discharging from the top of the furnace (“Top”
is as viewed for an upflow installation). The induced draft
blower can be rotated 90 degrees for Category I venting.
Refer to the following figure. For horizontal installations,
a four inch single wall pipe can be used to extend the in
-
duced draft blower outlet 1/2” beyond the furnace cabinet.
Vent the furnace in accordance with the National Fuel Gas
Code NFPA 54/ANSI Z223.1 - latest edition. In Canada,
vent the furnace in accordance with the National Standard
of Canada, CAN/CGA B149.1 and CAN/CGA B149.2 - lat-
est editions and amendments.
WARNING
To prevent death or serious illness to building occupants due
to flue products leaking into the building, proper installation
of gaskets and screws is essential for providing a gas tight
seal between the partition panel and the induced draft blower.
Make sure all wires are at least one inch from flue pipe.
Relocate junction box to right side of cabinet if nec essary.
Refer to
Electrical Connections
section of this manual for
instructions.
Masonry Chimneys
WARNING
Possibility of property damage, personal injury or death
- Damaging condensation can occur inside masonry chimneys
when a single fan assisted Category 1 appliance (80% AFUE fur
-
nace) is vented without adequate dilution air. Do not connect
an 80% furnace to a masonry chimney unless the furnace is
common vented with the draft hood equipped appliance, or the
chimney is lined with a metal liner or B metal vent. All installa
-
tions using masonry chimneys must be sized in accordance with
the appropriate Venting Tables.
- If an 80% furnace is common vented with the draft hood
equipped appliance, the potential for condensation damage may
still exist with extremely cold conditions, long vent connec
-
tors, exterior chimneys, or any combination of these condi
-
tions, The risk of condensation damage is best avoided by using
the masonry chimney as a pathway for properly sized metal
liner or B metal vent.
Wash
Crown
Clay Tile Size: 8" x 8" x12"
(Each x 24" Length)
Clay Tile Size Generally
12" x 12" (24" Length)
1/2" to 1" Air Space
Second Floor
First Floor
Attic Floor
Roof Line
Throat
Damper
Breech
Clean Out
Fan Assisted
Forced Air
Furnace
Natural Draft
Water Heater
Water Heater
Vent Connector
Basement Floor
F.A.F. Vent
Connector
Typical Multiple Flue Clay Tile Chimney
Checklist Summary
This checklist serves as a summary of the items to be
checked before venting an 80% furnace into a masonry
chimney. In addition, we recommend that a qualified ser
-
viceman use this checklist to perform a yearly inspection of
the furnace venting system.
This checklist is only a summary. For detailed information
on each of the procedures mentioned, see the paragraph
referenced with each item.
This inspection is based upon a draft topical report, “Ma
-
sonry Chimney Inspection and Relining”, issued by the Gas
Research Institute. While not yet finalized, we believe this
report represents the best information on this subject which
is currently available.
