MORTEX
PRODUCTS
INC
501
TERMINAL
RD
FORT
WORTH,
TX
76106
Page
11
Figure 10: WR 36J29 Gas Valve
GAS PIPING INSTALLATION
Properly sized black iron, approved flexible or steel pipe must be
used when making the gas connections to the furnace. Check the
local codes on the use of flexible pipe. Some local codes do not
allow the use of flexible pipe. Always use a listed connector. Do
not use a connector that has been serviced by another gas appliance.
Some utility companies may require pipe sizes larger than the
minimum sizes listed in these instructions and in the codes. Some
local codes may require pipe sizes that are larger than the minimum
sizes listed in these instructions.
The installation of a drip leg and a ground union is required.
IMPORTANT:
Plan your gas supply piping route before
determining the gas entry. Use 90 degree service elbow(s), or short
nipples and conventional 90 degree elbow(s) to enter through the
cabinet access holes.
Figure 11: Supply Gas Piping
1
A 1/8” NPT plugged tapping, accessible for test gauge
connection, must be installed immediately upstream of the gas
connection to the furnace.
2
If local codes allow the use of a flexible gas appliance
connector, always use a new listed connector. So not use a
connector that has previously serviced another gas appliance.
3
Piping to units should conform to local and national
requirements for type and volume of gas handled, and pressure drop
allowed in the line. Refer to Table 4 to determine the number of
feet of pipe and the BTU Input to determine the proper size pipe for
the unit to be installed. The length of pipe will determine the pipe
diameter. Refer to Table 4. When several units are served by the
same main, the total capacity, BTU/H and length of main must be
considered. Avoid pipe sizes smaller than 1/2" (1.27 cm).
Table 4 allows for a 0.3" W.C. (0.075 kPa) pressure drop in the
ON / OFF
Pressure
Convertable
OUT P
IN P
VENT
Manifold Pressure Tap
Electrical Terminals
Gas Supply Line
Pressure Tap
GAS FLOW
Switch
Regulator
IN
L
E
T
O
U
TLE
T
Wrench Boss
FLOW
GAS LINE
GAS SUPPLY
GAS SUPPLY
GAS LINE
GAS SUPPLY PIPING
ON
P
O
S
IT
ION
O
F
F
PO
SI
T
IO
N
LINE VALVE
UNION
LINE VALVE
UNION
DRIP LEG
DRI
P
L
E
G
An overpressure protection device such as a pressure
regulator must be installed in the gas piping system up
stream of the furnace and must act to limit the downstream
pressure to the gas valve so it does not exceed 0.5 PSI (14”
WC (3.48 kPa)). Pressures exceeding 0.5 PSI (14” WC (3.48
kPa)) at the gas valve will cause damage to the gas valve,
the furnace, or some of its components. This will result in a
fire or explosion that will cause property damage and loss of
life.
1.
Purging of air from gas lines should be performed as
described in ANSI Z223.1 - latest edition “National Fuel
Gas Code”, or in Canada CAN/CGA-B149 codes.
2
When leak testing the gas supply piping system, the
appliance and its combination gas control must be isolated
during any pressure testing in excess of 14" W.C. (0.5 psi
(3.48 kPa)).
2.
The unit should be isolated from the gas supply piping
system by closing its field installed manual shut-off valve.
This manual shut-off valve should be located within 6 ft
(1.83 m) of the heater.
3.
Turn off all gas before installing appliance.
IMPORTANT
To prevent premature heat exchanger failure, the input to the
appliance, as indicated on the serial plate, must not exceed
the rated input by more than 5%.
Never apply a pipe wrench to the body of the gas valve
when installing or removing the gas pipe. The pipe wrench
must be placed on the gas valve “Wrench Boss”. Refer to
Figure 11.
Placing a wrench on the body of the gas valve will cause
damage to the valve causing improper operation and/or
leaking. This can result in a fire or explosion that can result
in personnel injury, property damage and loss of life.
