20
General Furnace Layout
Upflow Installations
When the gas piping enters through the right-hand side of the
furnace, the installer must supply the following fittings (starting
from the gas control valve).
■
90º elbows (2)
■
Close nipple
■
Straight pipe to reach the exterior of the furnace
■
A ground joint union, drip leg and manual shutoff valve must
also be supplied by the installer. In some cases, the installer
may also need to supply a transition piece from
¹⁄₂
" to another
pipe size.
When the gas piping enters through the left-hand side of the
furnace, the installer must supply the following fittings (starting
from the gas control valve).
■
Straight pipe to reach the exterior of the furnace
■
A ground joint union, drip leg and manual shutoff valve must
also be supplied by the installer. In some cases, the installer
may also need to supply a transition piece from
¹⁄₂
" to another
pipe size.
Gas Piping Checks
Before placing the unit in operation, leak test the unit and gas
connections.
Check for leaks using an approved chloride-free soap and water
solution, an electronic combustible gas detector or other
approved testing methods.
NOTE: Never exceed specified pressures for testing. Higher
pressure may damage the gas control valve and cause
subsequent overfiring, resulting in heat exchanger failure.
Disconnect this unit and the shutoff valve from the gas supply
piping system before pressure testing the supply piping system
with pressures in excess of
¹⁄₂
psig (3.48 kPa).
This unit must be isolated from the gas supply system by closing
its manual shutoff valve before pressure testing of gas supply
piping system with test pressures equal to or less than
¹⁄₂
psig
(3.48 kPa).
Propane Gas Tanks and Piping
A gas detecting warning system is the only reliable way to detect
a propane gas leak. Rust can reduce the level of odorant in
propane gas. Do not rely on your sense of smell. Contact a local
propane gas supplier about installing a gas detecting warning
system.
All propane gas equipment must conform to the safety standards
of the National Board of Fire Underwriters, NBFU Manual 58. For
satisfactory operation, propane gas pressure must be 11" W.C. at
the furnace manifold with all gas appliances in operation.
Maintaining proper gas pressure depends on three main factors:
■
Vaporization rate, depending on temperature of the liquid and
“wetted surface” area of the container or containers.
■
Proper pressure regulation. Two-stage regulation is
recommended for both cost and efficiency.
■
Pressure drop in the lines between the regulators, and
between 2
nd
stage regulator and the appliance. Pipe size will
depend on the length of the pipe run and the total load of all
appliances.
A. Manual shutoff valve location
(upstream of ground joint pipe union)
B. Height required by local codes
C. Ground joint pipe union (upstream of
gas control valve)
D. Drip leg
E. Reducing coupling—
¹⁄₂
" x
¹⁄₈
"
with
¹⁄₈
" pipe plug to
measure line gas pressure
‘‘
A
B
C
D
E
Goodman 63
To avoid the possibility of explosion or fire, never use a
match or open flame to test for leaks.
WARNING
Goodman 72
To prevent property damage or personal injury due to
fire, the following instructions must be performed
regarding gas connections, pressure testing, location
of shutoff valve and installation of gas piping.
WARNING
Goodman 64
If the gas furnace is installed in a basement, and
excavated area or a confined space, it is strongly
recommended to contact a propane supplier to install a
gas detecting warning device in case of a gas leak.
—
Since propane gas is heavier than air, any leaking can
settle in low areas or confined spaces.
—
Propane gas odorant may fade, making the gas
undetectable except with a warning device.
WARNING