Goodman GMP Installation & Operating Instructions Manual page 7

GAS PIPING & GAS PIPE CAPACITY TABLE
Check the rating plate to make certain that the unit is equipped to burn the type of gas supplied.
Care should be taken after the installation of this appliance that the gas control valve is not sub-
jected to high gas supply line pressure.
In making connections, avoid strains as they may cause noise and damage the controls. Always
use a back-up wrench when tightening the gas supply pipe to the gas control valve.
The furnace and its individual shut-off must be disconnected from the gas supply piping system
during any pressure testing of that system at test pressures in excess of 1/2 psig (3.5kPa).
The furnace must be isolated from the gas supply piping system by closing its individual manual
shut-off valve during any pressure testing of the gas supply piping system at pressures equal to or
less than 1/2 psig (3.5 kPa).
Check for leaks in the gas supply using soap bubbles or other approved methods.
WARNING
NEVER USE AN OPEN FLAME TO CHECK FOR GAS LEAKS. THIS PRACTICE MAY CAUSE A
FIRE, EXPLOSION, BODILY HARM INCLUDING DEATH OR PROPERTY DAMAGE.
Pipe joint compound must be resistant to the affects of LP gas.
A union and listed manual shutoff must be installed exterior to the furnace cabinet so the control
assembly may be easily removed.
A 1/8" NPT plug on the supply pipe at the manual valve for the purpose of making pressure meas-
urement must also be installed. The valve should be readily accessible for turning on or off. A
capped sediment trap, sometimes referred to as a drip leg, should be installed in the gas supply
pipe as close to the furnace as possible. This trap must incorporate a change of direction of the
gas flow.
Refer to local codes or the below mentioned publications for proper location of the manual shutoff
and sediment trap lengths.
All gas piping must conform to local codes, or in the absence of local codes, to the National Fuel
Gas Code ANSI Z223.1 and / or CAN/CGA B149 Installation Codes.
The gas pipe must be sized to eliminate undue pressure drop. See pipe capacity table or consult
your local utility.
NOTE: Copper tubing must not be used for natural gas installations where more than 3 grains of
hydrogen sulfide per 100 standard cubic feet of gas is present.
For installations in the Commonwealth of Massachusetts see Fuel Gas and Plumbing Code 248
CMR: Appendix C.
3
Capacity of gas pipe of different diameters and length in ft /hr. with a pressure drop of 0.3" W.C.
and a specific gravity of 0.60 (natural gas).
PIPE LENGTH OF PIPE IN FEET
IO137 7