Bryant Gas Air 393U - Manual (Page 7)

Sizes 50, 80,100 8s 125 using natural gas are equip­
ped with a factory-installed combination pressure
regulator and main shut off - pilot supply shut off
valve. This control is inside the furnace cabinet.
A separate manual shut-off valve is not supplied
with these furnaces. Consult local codes regarding
the need for placing a separate shut-off valve out­
side the furnace cabinet as shown in Figure 5.
Where a gum filter is required by local regulations,
place filter between manual gas cock and pilot
cock. See Figure 6.
Place a ground joint union between the gas control
manifold and the manual gas shut-off valve.
4. Support all piping with appropriate straps, hang­
ers, etc. This will maintain proper slope of the lines
as installed and will remove unnecessary strain on
the furnace and its controls. It will also prevent
the piping from being moved accidentally from its
installed position.
5. Joint compounds — (pipe dope) should be applied
sparingly and only to the male threads of the joints.
Consult local supplier for type of compound to be
used with LP gas.
6. After all connections have been made, purge
the lines and check for leakage. Never purge a line
into a combustion chamber. Never use matches,
candles, flame, or other sources of ignition for the
purpose of checking leakage.
VENTING THE FURNACE
Consult local codes. Unless the local codes direct
otherwise the furnace may be vented to a permanent
chimney, or to a listed Type B or Type C gas vent.
This Bryant gas-fired furnace has a built in draft
diverter. Therefore, it remains only to connect the
furnace vent collar to the chimney or gas vent to be
used. The following recommendations are made:
1. Select a flue connection material that is satis­
factory for the installation, and that meets the
requirements of the local codes.
2. The flue connection pipe must be the same size
as the outlet collar on the furnace. No reduction in
this size is permissible in the pipe run.
3. Run pipe as directly as possible with a minimum
number of turns. The maximum length of horizontal
run should not exceed 75 percent of the height of
the chimney.
4. Maintain a minimum of 1/4 inch per linear foot
upward slope from the furnace to the chimney on all,
horizontal runs.
5. Rigidly support the flue pipe with hangers and
straps to insure that there will be no movement
after installation.
6. Extend the flue connection pipe through the
chimney wall flush with the inner face of the chim­
ney liner. Never connect into a chimney serving an
open fireplace, unless the fireplace opening is
sealed off.
7. The chimney or gas vent should extend high
enough above the roof or neighboring obstruction
so that wind from any direction will not create a
positive pressure in the vicinity of the outlet of
the chimney or gas vent. The installer is referred
to Part V of American Standard “Installation of
Gas Appliances and Gas Piping, ASA Z21.30-1964
for detailed information on chimney and gas vent
use. In general the chimney or gas vent should
extend 3 feet higher than the point of emergence
through the roof, and at least 2 feet higher than any
object within a radius of 15 feet.
8. If more than one appliance is vented into the
same chimney, the cross sectional area of the chim­
ney must be as large as the largest flue pipe being
connected, plus 50 percent of the cross sectional
areas of the additional flue pipes being connected.
9. If more than one appliance is manifolded into
the same flue connecting pipe, the cross sectional
area of this manifold pipe must be as large as the
sum of the cross sectional areas of the pipes con­
necting into it.
393U
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