Goodman GM9S80 Service And Troubleshooting page 22

SYSTEM OPERATION
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
supply 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.
9. Connect the furnace to the building piping by one of
the following methods:
– Rigid metallic pipe and fittings.
– Semi-rigid metallic tubing and metallic fittings. Alu-
minum alloy tubing must not be used in exterior
locations. In order to seal the grommet cabinet
penetration, rigid pipe must be used to reach the
outside of the cabinet. A semi-rigid connector to the
gas piping may be used from there.
10. Use listed gas appliance connectors in accordance
with their instructions. Connectors must be fully in the
same room as the furnace.
11. Protect connectors and semi-rigid tubing against
physical and thermal damage when installed. Ensure
aluminum-alloy tubing and connectors are coated to
protect against external corrosion when in contact
with masonry, plaster, or insulation, or subjected to
repeated wetting by liquids such as water (except rain
water), detergents, or sewage.
Edges of sheet metal holes may be sharp. Use gloves a precau-
tion when removing hole plugs.
GAS PIPING CHECKS
Before placing unit in operation, leak test the unit and gas
connections.
To avoid the possibility 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 be-
22
CAUTION
WARNING
fore 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 shut-
off 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
Propane gas is heavier than air and any leaking gas can settle
in any low areas or confined spaces. To prevent property dam-
age, 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 stan-
dards of the National Board of Fire Underwriters, NBFU
Manual 58.
For satisfactory operation, propane gas pressure must be
11 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
recommended for both cost and efficiency).
3. Pressure drop in lines between regulators, and be-
tween second stage regulator and the appliance. Pipe
size will depend on length of pipe run and total load of
all appliances.
Complete information regarding tank sizing for vaporiza tion,
recommended regulator settings, and pipe sizing is avail-
able from most regulator manufacturers and propane gas
suppliers. Always use a pipe sealant approved for natural
gas and LP gas.
Refer to the following illustration for typical propane gas in-
stallations and piping.
First Stage
Regulator
200 PSIG
Maximum
Typical Propane Gas Installation
WARNING
5 to 15 PSIG
(20 PSIG Max.)
Continuous
11" W.C.
Second Stage
Regulator