VENTING
Step 1—General Venting Requirements
Venting for furnace should be to the outside and in accordance
with local codes or requirements of local utility. In the absence of
local codes, venting should conform to the NFGC NFPA 54/ANSI
Z223.1-1992 Part 7 or CAN/CGA-B149 Installation Codes Sec-
tion 7, the vent manufacturer’s Installation Instructions, and the
A.G.A./GAMA Venting Tables supplied with furnace.
These furnaces are equipped with induced-combustion blowers
and are classified as Category I forced air furnaces in accordance
with ANSI/A.G.A. Z21.47 and C.G.A. 2.3 Central Furnace Stan-
dards. Category I furnaces use non-positive, non-condensing vent
systems, and may be connected to lined masonry chimneys which
have been sized and installed per the enclosed procedures. Cat-
egory I furnaces can not be vented into a vent system with any
Category II, III, or IV appliance. It must be vented vertically or
nearly vertically, unless installed with a listed mechanical venter in
accordance with horizontal venting instructions in the Horizontal
Venting section below. A Category I furnace must not be con-
nected to any portion of a mechanical draft system operating under
positive pressure.
Venting of these furnaces into a lined masonry chimney could
form flue gas condensate due to cold surfaces and oversizing. If
condensate is present in the masonry chimney, a drain must be
provided to prevent condensate flow into the vent connector and
furnace. (Refer to the NFGC, Section 7.9 for additional informa-
tion on condensate drains.) Field experience on induced-
combustion furnaces has shown that venting through a properly
sized Type B-1 vent significantly reduces vent condensation.
Condensate is acidic and could corrode vent materials. Therefore,
the manufacturer suggests (but does not require) that these
furnaces be connected to vent systems constructed of Type B-1
vent material.
This furnace may be common vented only with other Category I
appliances. Common venting is allowed as permitted by national
and/or local codes. Refer to the A.G.A./GAMA Venting Tables
supplied with furnace for proper sizing and setup.
The vent must be terminated with a listed vent cap or roof
assembly. This venting must be installed in accordance with the
vent manufacturer’s Installation Instructions and be in accordance
with all local and/or national codes.
The following requirements are provided for a safe venting
system:
1. Be sure chimney flue is clear of any dirt or debris.
2. Be sure chimney is not servicing an open fireplace.
3. Never reduce pipe size below outlet size of furnace without
checking the A.G.A./GAMA Venting Tables supplied with
furnace.
4. All pipe should be supported using proper clamps and/or
straps. These supports should be at least every 4 ft.
5. All horizontal runs of pipe should slope upward at least 1/4 in.
per ft from furnace to vent terminal.
6. All runs of pipe should be as short as possible with as few
turns as possible.
7. Seams should be tightly joined and checked for leaks.
8. The flue pipe must not extend into chimney but be flush with
inside wall.
9. The chimney or vent pipe must extend at least 3 ft above the
highest point where it passes through a roof of a building and
at least 2 ft higher than any portion of a building within a
horizontal distance of 10 ft. It shall also extend at least 5 ft.
above highest connected equipment flue collar.
NOTE:
The GAMA venting tables MUST be used; DO NOT use
Carrier’s Single-Stage Vent Tables for Category I Fan-Assisted
Furnaces, as they are based on different input ratings.
Step 2—Pre-Installation Vent System Inspection
Before furnace is installed, it is highly recommended that any
existing vent system be completely inspected.
For a chimney or Type B vent, this should include the following:
1. Inspection for any deterioration in chimney or Type B vent. If
deterioration is discovered, the chimney must be repaired or
Type B vent must be replaced.
2. Inspection to ascertain that vent system is clear and free of
obstructions. Any blockage must be cleared before installing
furnace.
3. Cleaning chimney or Type B vent if previously used for
venting a solid fuel burning appliance or fireplace.
4. Confirming that all unused chimney or Type B vent connec-
tions are properly sealed.
5. Verification that chimney is properly lined and sized per
applicable codes.
Step 3—Removal of Existing Furnaces from
Common Vent Systems
If furnace being replaced was connected to a common vent system
with other appliances, the following steps shall be followed with
each appliance connected to the venting system placed in opera-
tion, while any other appliances connected to the venting system
are not in operation:
1. Seal any unused openings in the venting system.
2. Inspect the venting system for proper size and horizontal pitch
as required in the National Fuel Gas Code, ANSI Z223.1 or
the CAN/CGA B149 Installation Codes and these instructions.
Determine that there is no blockage or restriction, leakage,
corrosion, and other deficiencies which could cause an unsafe
condition.
3. In so far as is practical, close all building doors and windows
and all doors between the space in which the appliance(s)
connected to the venting system are located and other spaces
of the building. Turn on clothes dryers and any appliance not
connected to the venting system. Turn on any exhaust fans,
such as range hoods and bathroom exhausts, so they shall
operate at maximum speed. Do not operate a summer exhaust
fan. Close fireplace dampers.
4. Follow the lighting instructions. Place the appliance being
inspected in operation. Adjust thermostat so appliance shall
operate continuously.
5. Test for draft hood equipped appliance spillage at the draft
hood relief opening after 5 minutes of main burner operation.
Use the flame of a match or candle.
6. After it has been determined that each appliance connected to
the venting system properly vents when tested as outlined
above, return doors, windows, exhaust fans, fireplace damp-
ers, and any other gas-burning appliance to their previous
conditions of use.
7. If improper venting is observed during any of above tests, the
venting system must be corrected.
Vent system or vent connectors may need to be resized. For any
other appliances when resizing vent systems or vent connectors,
system or connector must be sized to approach minimum size as
determined using appropriate table found in the NFGC or NSC-
NGPIC.
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