INSTALLATION CONSIDERATIONS
23
To connect the furnace to the building’s gas piping, the install
-
er must supply a ground joint union, drip leg, manual shutoff
valve, and line and fittings to connect to gas valve. In some
cases, the installer may also need to supply a transition piece
from 1/2" pipe to a larger pipe size.
The following stipulations apply when connecting gas piping.
Refer to the following figures for typical gas line connections
to the furnace.
1. Use black iron or steel pipe and fittings for the building
piping.
2. Use pipe joint compound on male threads only. Pipe
joint compound must be resistant to the action of the
fuel used.
3. Use ground joint unions.
4. Install a drip leg to trap dirt and moisture before it can
enter the gas valve. The drip leg must be a minimum of
three inches long.
5. Install a 1/8" NPT pipe plug fitting, accessible for test
gage connection, immediately upstream of the gas sup
-
ply connection to the furnace.
6. Use two pipe wrenches when making connection to
the gas valve to keep it from turning. The orientation of
the gas valve on the manifold must be maintained as
shipped from the factory.
7. Install a manual shutoff valve between the gas meter
and unit within six feet of the unit. If a union is installed,
the union must be downstream of the manual shutoff
valve, between the shutoff valve and the furnace.
8. Tighten all joints securely.
GAS PIPING CHECKS
Before placing unit in operation, leak test the unit and gas
connections.
WARNING
T
O AVOID THE POSSIBLITY OF EXPLOSION OR FIRE, NEVER USE A MATCH
OR OPEN FLAME TO TEST FOR LEAKS.
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 valve and cause subsequent
overfiring, resulting in heat exchanger failure. Disconnect this
unit and 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). Isolate this unit from the gas
supply piping system by closing its external manual gas shutoff
valve before pressure testing supply piping system with test
pressures equal to or less than 1/2 psig (3.48 kPa).
PROPANE GAS TANKS AND PIPING
WARNING
P
ROPANE GAS IS HEAVIER THAN AIR AND ANY LEAKING GAS CAN SETTLE IN
ANY LOW AREAS OR CONFINED SPACES.
T
O PREVENT PROPERTY DAMAGE,
PERSONAL INJURY, OR DEATH DUE TO FIRE OR EXPLOSION CAUSED BY A
PROPANE GAS LEAK, INSTALL A GAS DETECTION WARNING DEVICE.
A gas detecting warning system is the only reliable way to
detect a propane gas leak. Iron oxide (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. If the presence of gas is
suspected, follow the instructions on this page.
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
10 inch WC at the furnace manifold with all gas appli ances
in operation. Maintaining proper gas pressure depends on
three main factors:
1. Vaporization rate, depending on temperature of the liquid,
and “wetted surface” area of the con tainer or containers.
2. Proper pressure regulation. (Two-stage regulation is rec
-
ommended for both cost and efficiency).
3. Pressure drop in lines between regulators, and between
second stage regulator and the appliance. Pipe size will
depend on length of pipe run and total load of all appli
-
ances.
Complete information regarding tank sizing for vaporiza tion,
recommended regulator settings, and pipe sizing is available
from most regulator manufacturers and propane gas suppliers.