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Specifications are subject to change without notice
7. Masonry Chimney Venting
CARBON MONOXIDE POISONING, FIRE AND
EXPLOSION HAZARD.
Failure to properly vent this furnace could result in
personal injury, death and/or property damage.
Follow these installation instructions.
!
Chimney Inspection
All masonry chimney construction must conform to the Standard for
Chimneys, Fireplaces, Vents, and Solid Fuel--Burning Appliances
ANSI/NFPA 211--2006 and to any state or local codes applicable.
The chimney must be in good condition and a complete chimney
inspection must be conducted prior to furnace installation. If the
inspection reveals damage or abnormal conditions, make
necessary repairs or seek expert help. See “The Chimney
Inspection Chart”
Figure 9.
Measure inside area of tile--liner and
exact height of chimney from the top of the chimney to the highest
appliance flue collar or drafthood outlet.
Connector Type
To reduce flue gas heat loss and the chance of condensate
problems, the vent connector
must
be double--wall Type B vent.
Venting Restrictions for Chimney Types
Interior Chimney --
has no sides exposed to the outdoors below
the roofline. Venting is permitted into an interior masonry chimney
in accordance with Table 13.8 and section 13.2 of the National Fuel
Gas Code ANSI Z223.1/NFPA 54--2006, if the furnace is
common--vented with at least one draft hood--equipped water
heater or furnace.
These furnaces are NOT permitted to be vented into interior
masonry chimneys singly (not common--vented with a draft
hood--equipped water heater or furnace).
Exterior Chimney --
has one or more sides exposed to the
outdoors below the roof line. All installations with a 99% Winter
Design Temperature* below 17
°
F (--8
°
C) must be common vented
only with a draft hood equipped Category I appliance.
*
The 99.6% Winter Design Dry--Bulb (db) temperatures are
found in the 1997 or 2001 ASHRAE Climatic Design
Information chapter, Table 1A (United States) and 2B
(Canada), or the 2005 ASHRAE Fundamentals Handbook,
Climatic Design Information chapter, and the CD--ROM
included with the 2005 ASHRAE Fundamentals Handbook.
Chimneys shall conform to the Standard for Chimneys, Fireplaces,
Vents, and Solid Fuel Burning Appliances ANSI/NFPA 211--2006
and must be in good condition.
Refer to Sections 13.1.9 or 13.2.20 of the NFGC or the authority
having jurisdiction to determine whether relining is required.
If relining is required, use a properly sized listed metal liner or
Type--B vent to reline the chimney.
Inspections before the sale and at the time of installation will
determine the acceptability of the chimney or the need for repair
and/or (re)lining. Refer to the Chimney Inspection Chart to perform
a chimney inspection.
If the inspection of a previously used tile--lined chimney:
a. Shows signs of vent gas condensation, the chimney should
be relined in accordance with local codes and the authority
having jurisdiction. The chimney should be relined with a
listed metal liner or Type--B vent to reduce condensation. If a
condensate drain is required by local code, refer to the
NFGC, Section 12.1 for additional information on
condensate drains.
b. Indicates the chimney exceeds the maximum permissible
size in the tables, the chimney should be rebuilt or relined to
conform to the requirements of the appliances being installed
and the authority having jurisdiction.
A chimney without a clay tile liner, which is otherwise in good
condition, shall be rebuilt to conform to ANSI/NFPA 211 or be lined
with a UL listed metal liner or UL listed Type--B vent. Relining with a
listed metal liner or Type--B vent is considered to be a
vent--in--a--chase.
If a metal liner or Type--B vent is used to line a chimney, no other
appliance shall be vented into the annular space between the
chimney and the metal liner.
APPLIANCE APPLICATION REQUIREMENTS
Appliance operation has a significant impact on the performance of
the venting system. If the appliances are sized, installed, adjusted,
and operated properly, the venting system and/or the appliances
should not suffer from condensation and corrosion. The venting
system and all appliances shall be installed in accordance with
applicable listings, standards, and codes.
The furnace should be sized to provide 100 percent of the design
heating load requirement plus any margin that occurs because of
furnace model size capacity increments. Heating load estimates
can be made using approved methods available from Air
Conditioning Contractors of America (Manual J); American Society
of Heating, Refrigerating, and Air--Conditioning Engineers; or other
approved engineering methods. Excessive oversizing of the
furnace could cause the furnace and/or vent to fail prematurely.
When a metal vent or metal liner is used, the vent or liner must be in
good condition and be installed in accordance with the vent or liner
manufacturer’s instructions.
To prevent condensation in the furnace and vent system, the
following precautions must be observed:
1. This furnace is designed for minimum continuous return--air
temperature of 60
°
F (155
°
C) db or intermittent operation down
to 55
°
F (13
°
C) db such as when used with a night setback
thermostat.
2. Adjust the gas input rate per the installation instructions. Low
gas input rate causes low vent gas temperatures, causing
condensation and corrosion in the furnace and/or venting
system. Derating is permitted only for altitudes above 2000
′
(610 m).
3. Adjust the air temperature rise to the midpoint of the rise range
or slightly above. Low air temperature rise can cause low vent
gas temperature and potential for condensation problems.
4. Set the thermostat heat anticipator or cycle rate to reduce short
cycling.
Air for combustion must not be contaminated by halogen
compounds, which include chlorides, fluorides, bromides, and
iodides.
These compounds are found in many common home products such
as detergent, paint, glue, aerosol spray, bleach, cleaning solvent,
salt, and air freshener, and can cause corrosion of furnaces and
vents. Avoid using such products in the combustion--air supply.
Furnace use during construction of the building could cause the
furnace to be exposed to halogen compounds, causing premature
failure of the furnace or venting system due to corrosion.
Vent dampers on any appliance connected to the common vent can
cause condensation and corrosion in the venting system. Do not
use vent dampers on appliances common vented with this furnace.
