39
Rev. 2
PRODUCT DESIGN
CONNECTING THE GAS PIPING - NATURAL GAS
Refer to Installation Instructions for the general layout of the
furnace. The following rules apply:
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. (Inside or outside of furnace.)
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. 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 the same as
shipped from the factory.
6. Install a manual shutoff valve. This shutoff valve should
be conveniently located within six (6) feet of the unit,
and between the meter and unit. The shutoff valve should
be upstream of the dripleg and union.
7. Tighten all joints securely.
8. The furnace shall be connected to the building piping by
one of the following.
a.
Rigid metallic pipe and fittings.
b.
Semirigid metallic tubing and metallic fittings. Alu-
minum alloy tubing shall not be used in exterior
locations.
c.
Listed gas appliance connectors used in accor-
dance with the terms of their listing that are com-
pletely in the same room as the equipment.
d.
In "b" and "c" above, the connector or tubing shall
be installed so as to be protected against physi-
cal and thermal damage. Aluminum-alloy tubing
and connectors shall be coated to protect against
external corrosion where they are in contact with
masonry, plaster, or insulation or are subject to
repeated wettings by such liquids as water (ex-
cept rain water), detergents, or sewage.
CHECKING THE GAS PIPING
CAUTION
To avoid the possibility of property damage, personal
injury or fire, the following instructions must be per-
formed regarding gas connections, pressure testing,
location of shutoff valve and installation of gas piping.
The unit and its gas connections must be leak tested before
placing in operation. Because of the danger of explosion or
fire, never use a match or open flame to test for leaks. Never
exceed specified pressure for testing. Higher pressure may
damage the gas valve and cause overfiring which may result
in heat exchanger failure.
This unit must be isolated from the gas supply system by
closing its individual manual shutoff valve during any pres-
sure testing of the gas supply piping system at test pres-
sures equal to or less than 1/2 psig (3.48 kPa).
TANKS AND PIPING - PROPANE UNITS
WARNING
PERSONAL INJURY HAZARD
Iron oxide (rust) can reduce the level of odorant in pro-
pane gas. A gas detecting device is the only reliable
method to detect a propane gas leak. Contact your lo-
cal propane supplier about installing a gas detecting
warning device to alert you in the event that a gas
leak should develop.
Failure to detect a propane gas leak could result in an
explosion or fire which could cause serious personal
injury or death.
All propane gas equipment must conform to the safety stan-
dards of the National Board of Fire Underwriters (See NBFU
Manual 58).
For satisfactory operation, propane gas pressure must be
10 inch W.C. at the furnace manifold with all gas appliances
in operation. Maintaining proper gas pressure depends on
three main factors.
1. Vaporization rate, which depends on (a) temperature of
the liquid, and (b) "wetted surface" area of the container
or containers.
2. Proper pressure regulation. (Two stage regulation is rec-
ommended from the standpoint of both cost and effi-
ciency.)
3. Pressure drop in lines between regulators, and between
second stage regulator and the appliance. Pipe size re-
quired will depend on length of pipe run and total load of
all appliances.
Complete information regarding tank sizing for vaporization,
recommended regulator settings, and pipe sizing is avail-
able from most regulator manufacturers and propane gas
suppliers.
Propane is an excellent solvent, and special pipe dope must
be used when assembling piping for this gas as it will quickly
dissolve white lead or most standard commercial com-
pounds. Shellac base compounds resistant to the actions
of liquefied petroleum gases such as Gasolac, Stalactic,
Clyde's or John Crane are satisfactory.
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