Installing Your Furnace - Williams 3501522A Owner's Manual

INSTALLING YOUR FURNACE

LOUVERS / GRILLES AND SCREENS COVERING
FREE AREA OPENINGS
If a screen is used to cover the opening(s), it must not be
smaller than 1/4-inch mesh. Use the free area of a louver
or grille to determine the size opening required to provide
the free area specified. If the free area is not known,
assume a 20% free area for wood and a 60% free area for
metal louvers or grilles.
EXAMPLE 1
FURNACE LOCATED IN UNCONFINED SPACE.*
*An unconfined space must have a volume of a minimum
50 cubic feet per 1000 BTU/hr. of total of all appliances in
area. Adjoining rooms may be included only if there are
no doors between the rooms, or if special provisions
are made such as ventilation grilles installed between
connecting rooms.
Page 11, Figure 8 shows the minimum area in square feet'
based on 8 foot ceiling heights, required for different BTU/
hr. input ratings.
A. If your furnace is in an open area (unconfined space*)
the air that leaks through the cracks around doors
and windows may be enough for combustion and
ventilation air. The doors should not fit tight. The
cracks around windows should not be caulked or
weather stripped.
To determine if infiltration air is adequate, perform
following checks:
1. Close all doors and windows. If you have a fireplace,
start a fire and wait until flames are burning vigorously.
2. Turn on all exhausting devices, such as: kitchen and
bathroom exhaust fans, dryers (gas and electric)
3. Turn on all vented gas appliances, such as: heating
equipment (includes any room heaters), water heater
4. Wait ten (10) minutes for drafts to stabilize.
5. Check for draft hood spillage at each appliance. Hold
a lighted match 2 inches from draft opening.
See Figure 6
B. No Spillage
If the match flame pulls toward draft hood - this
indicates sufficient infiltration air:
1. Return exhausting devices and appliances to the
condition you found them.
C. Draft Hood Spills
If there is spillage at a draft hood (match goes out or
flame wavers away from draft hood):
1. Check for plugged flue connectors and chimneys.
Check and repair, stoppage and test again.
2. If you have a fireplace, open a window or door near the
fireplace and then check for spillage.
a) If spillage stops, do not use the fireplace without a
nearby window or door open until you can supply
fresh air by a permanent duct.
10
VENTED ROOM HEATERS
3. If you have kitchen and bathroom exhaust fans, turn
them off and check for spillage.
a) If spillage stops, do not use exhaust fans until you
can supply fresh air by a permanent duct.
WARNING: Danger of property damage,
bodily injury or loss of life. Draft hood spillage, with
unobstructed vents, indicates that additional air must
be brought into the structure from outside. Keep a
window open (minimum 2 inches) near the appliance
until a permanent air duct is installed.
FIGURE 6 - DRAFT HOOD SPILLAGE
VENT PIPE
DRAFT HOOD
OPENING
(match or
smoke pen)
TYPICAL WATER
HEATER
4. Spillage means air starvation and a fresh air duct or
air intakes must be installed to provide air directly
to the furnace or other gas appliance.
D. If spillage exists or when the furnace is in a building
of tight construction where the windows and doors
are weather-stripped, air for combustion and
ventilation must be obtained from outdoors or space
open to the outdoors.
Provide an opening(s) having a total free area of 1-square
inch per 4,000 BTU/hr. for the total of all appliances. The
required area is shown on page 12, Figure 11.
Figure 7 shows a typical duct going into ventilated crawl
space or attic.
1. Duct must terminate at a point not more than 1 foot
above the floor.
2. Duct size must be at least 1 inch of free area for each
4000 BTU/hr. of input of all appliances in area.
EXAMPLE 2
FURNACE LOCATED IN CONFINED SPACE
If furnace is installed in a confined space, it must be
provided with free air for proper combustion and
ventilation of flue gases by one of the following methods.
A. ALL AIR FROM INSIDE BUILDING:
If the confined space adjoins an unconfined, provide two
permanent openings, one within 12 inches of the top and
one within 12 inches of the bottom of the room connecting
directly to unconfined space. Each opening must have a
free area of at least 100 square inches or 1 square inch per
1,000 BTU/hr. combined input of appliances in one room if
combined input exceeds 100,000 BTU/hr.
VENT PIPE
DRAFT HOOD
OPENING
(match or
smoke pen)
WALL
FURNACE