035-20499-001 Rev. B (1004)
Unitary Products Group
15
Vent and Supply (Outside) Air Safety Check Procedure
Follow the procedure in ANSI Z223.1 National Fuel Gas Code. Refer to
the section on the “Recommended Procedure for Safety Inspection of
an Existing Appliance” or in Canada B149.1-00 Natural Gas and Pro-
pane Installation Code section on “Venting Systems and Air Supply for
Appliances” and all local codes. In addition to the procedure specified in
ANSI Z223.1, It is recommended that you follow the venting safety pro-
cedure below. This procedure is designed to detect an inadequate ven-
tilation system that can cause the appliances in the area to operate
improperly causing unsafe levels of Carbon Monoxide or an unsafe
condition to occur.
1.
Inspect the venting system for proper size and horizontal pitch.
Determine that there is no blockage, restriction, leakage, corrosion
or other deficiencies, which could cause an unsafe condition
2.
Close all building doors and windows and all doors.
3.
Turn on clothes dryers and TURN ON any exhaust fans, such as
range hoods and bathroom exhausts, so they shall operate at
maximum speed. Open the fireplace dampers. Do not operate a
summer exhaust fan.
4.
Follow the lighting instructions. Place the appliance being
inspected in operation. Adjust thermostat so the appliance shall
operate continuously.
5.
Test each appliance (such as a water heater) equipped with a draft
hood for spillage (down-draft or no draft) at the draft hood relief
opening after 5 minutes of main burner operation. Appliances that
do not have draft hoods need to be checked at the vent pipe as
close to the appliance as possible. Use a combustion analyzer to
check the CO2 and CO levels of each appliance. Use a draft
gauge to check for a downdraft or inadequate draft condition.
6.
After it has been determined that each appliance properly vents
when tested as outlined above, return doors, windows, exhaust
fans, fireplace dampers and any other gas burning appliance to
their normal condition.
7.
If improper venting is observed during any of the above tests, a
problem exists with either the venting system or the appliance
does not have enough combustion air (Supply Air from outside) to
complete combustion. This condition must be corrected before the
appliance can function safely.
NOTE:
An unsafe condition exists when the CO reading exceeds 100
ppm and the draft reading is not in excess of - 0.1 in. W.C. (-25
kPa) with all of the appliance(s) operating at the same time.
8.
Any corrections to the venting system and / or to the supply (out-
side) air system must be in accordance with the National Fuel Gas
Code Z223.1 or CAN/CGA B149.1-00 Natural Gas and Propane
Installation Code (latest editions). If the vent system must be
resized, follow the appropriate tables in Appendix G of the above
codes or for this appliance only refer to Table 9 of these instruc-
tions.
Ventilated Combustion Air
The ventilated attic space or a crawl space from which the combustion
air is taken must comply with the requirements specified in “AIR
SOURCE FROM OUTDOORS” in this instruction or in Section 5.3, Air
for Combustion and Ventilation of the National Fuel Gas Code, ANSI
Z223.1 (latest edition). This type installation requires two properly sized
pipes. One brings combustion air from a properly ventilated attic space
or crawl space and a second pipe that extends from the furnace vent
connection (top right of unit) to the exterior of the building. Refer to
Table 9 for intake pipe sizing, allowable length and elbow usage. Follow
all notes, procedures and required materials in the SEALED COMBUS-
TION AIR SUPPLY section in these instructions when installing the
combustion air pipe from the unit and into a ventilated attic space or
crawl space. DO NOT terminate vent pipe in an Attic or Crawl Space.
Ventilated Combustion Air Termination
Refer to Figure 21 for required attic termination for the combustion air
intake pipe. For attic termination, use two 90 elbows with the open end
in a downward position. Be sure to maintain 12” (30 cm) clearance
above any insulation, flooring or other material.
A crawl space combustion air installation consists of a straight pipe from
the PVC coupling on the burner box that extends into the crawl space
and terminates with a 1/4” (6.35 mm) mesh screen and no elbows.
FIGURE 20:
Outside and Ambient Combustion Air
GABLE
VENT
GAS
VENT
SOFFIT
VENT
VENTILATED
ATTIC
TOP ABOVE
INSULATION
OPTIONAL
INLET (a)
OUTLET
AIR (a)
VENTILATED
CRAWL SPACE
GAS
WATER
HEATER
VENTILATED
ATTIC
TOP ABOVE
INSULATION
GAS
VENT
GABLE
VENT
SOFFIT
VENT
GAS
WATER
HEATER
INLET
AIR (a)
INLET
AIR (b)
GAS
VENT
OUTLET
AIR (a)
OUTLET
AIR (b)
INLET
AIR (a)
INLET
AIR (b)
GAS
WATER
HEATER
FURNACE
1. An opening ma
y
be used in lieu of a duct to provide to provide the outside air
suppl
y
to an appliance unless otherwise permitted b
y
the authorit
y
having
jurisdiction. The opening shall be located within 12” (30.5 cm) horizontall
y
from,
the burner level of the appliance. Refer to “AIR SOURCE FROM OUTDOORS
AND VENT AND SUPPLY AIR SAFETY CHECK” in these instructions for
additional information and safet
y
check procedure.
2. The duct shall be either metal, or a material meeting the class 1
requirements of CAN4-S110 Standard for Air Ducts.
3. The duct shall be least the same cross-sectional area as the free
area of the air suppl
y
inlet opening to which it connects.
4. The duct shall terminate within 12 in (30.5 cm) above, and
within 24 in (61 cm) horizontall
y
from, the burner level of
the appliance having the largest input.
5. A square or rectangular shaped duct shall onl
y
be used
when the required free area of the suppl
y
opening is
9 in (58.06 cm ) or larger. When a square or rectangular
duct is used, its small dimension shall not be less than
3 in (7.6 cm).
2
2
6. An air inlet suppl
y
from outdoors shall be equipped with
a means to prevent the direct entr
y
of rain and wind.
Such means shall not reduce the required free area of
the air suppl
y
opening.
7.
An air suppl
y
inlet opening from the outdoors shall
be located not less than 12” (30.5 cm) above the
outside grade level.
FURNACE
FURNACE
AIR SUPPLY OPENINGS AND DUCTS
COMBUSTION AIR SOURCE FROM OUTDOORS
1. Two permanent openings, one within 12 in (30.5 mm) of the top and
one within 12 in (30.5 mm) of bottom of the confined space,
shall communicate directl
y
or b
y
means of ducts
with the outdoors, crawl spaces or attic spaces.
Two
permanent openings,
2. One permanent openings, commencing within 12 in (30.5 mm)of the
top of the enclosure shall be permitted where the equipment has
clearances of at least 1 in (2.54 cm) from the sides and back and
6 in (15.24 cm) from the front of the appliance. The opening shall
communicate directl
y
with the outdoors and shall have a minimum
free area of:
3. The duct shall be least the same cross-sectional area as the free
area of the air suppl
y
inlet opening to which it connects.
1 square in per 3000 Btu per hour (6.45
0.879 kW) of the
total input rating of all equipment located in the enclosure.
cm per
3
a.
Not less than the sum of all vent connectors in the confined space.
b.
4. The blocking effects of louvers, grilles and screens must be given
consideration in calculating free area. If the free area of a specific
louver aor grille is not known.
