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Installer's
Guide
TWINNING
FURNACES
These
fllrnaces
may be twinned.
Twinning
requires
that
two
fllrnaces
with
the same
configuration,
capacity,
and
airflow
must
be used.
They
shall
have
common
returns
with
equal
pressure
drops
or ducts
with
equivalent
lengths
and sizes.
See FieM Wiring
Diagrams
for proper
hookup.
GAS PIPING
The upflow/horizontal
fllrnace
is shipped
standard
lbr left
side
installation
of gas piping.
A knock-out
is provided
on the
right
side
fl)r an alternate
gas piping
arrangement.
See
Figure
46.
The installation
of piping
shall
be in accordance
with
piping
codes
and the
regulations
of the
local gas company.
Pipe joint
compound
must
be resistant
to the chemical
reaction
with
liquefied
petroleum
gases.
Reler
to piping
Table
10, lbr delivery
sizes.
Connect
gas
supply
to the unit,
using
a ground
joint
union
and a manual
shut-off
valve
as shown
in Figures
46-48.
National
codes
require
a condensation
drip
leg to be installed
ahead
of the controls
as shown
in Figures
46-48.
The fllrnace
and
its individual
shut-off
valve
must
be discon-
nected
from
the gas supply
piping
system
during
any pressure
testing
of that
system
at test pressures
in excess
of 1/2 psig
(3.5 kPa).
The fllrnace
must
be isolated
from
the gas supply
piping
by
closing
its individual
manual
shut-off
valve
during
any
pressure
testing
of the gas supply
piping
system
at test
pressures
equal
to or less
than
1/2 psig (3.5 kPa).
NOTE:
Maximum pressure to the gas valve for natural gas is
13.8" W.C. Minimum pressure is 5.0" W.C. Maximum pres-
sure to the gas valve for propane is 13.8" W.C.
Minimum pressure is 11.0" W.C.
All gas fittings must be checked for leaks using a soapy
solution before lighting the furnace. DO NOT CHECK WITH
AN OPEN FLAME!
@
LEG
AUTOMATIC GAS VALVE
WITH MANUAL SHUTOFF
UPFLOW - LEFT HAND GAS PIPING
AUTOMATIC
GAS VALVE
WITH MANUAL
SHUTOFF
.........
_,,_
MAIN MANUAL
SHUTOFF VALVE
_GROUND
/
/
UNION
_/
JOINT
DRIP
LEG
UPFLOW-
RIGHT HAND GAS PIPING
_iiiliii,iiii_iii!!i!!
©
THE DOWNFLOW (VERTICAL) MAY BE INSTALLED LEFT OR RIGHT SIDE GAS PIPING
26
18-CD19D6-27
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