Nordyne M4RC Installation Instructions Manual page 26

h. Remove four screws (4) securing the gas manifold
assembly (5) to the burner assembly (6).
i. Set aside the screw's (4) and remove the gas manifold
assembly (5) from the burner assembly.
j. Carefully remove the burner orifices (7) from the
gas manifold assembly (5).
WARNING:
Do not attempt to drill the gas orifices. Use
only factory supplied orifices, improperly
drilled orifices may cause fire, explosion,
carbon monoxide poisoning, personal injury
or death.
k.
Read the rating plate affixed to the appliance to
determine its rated input (Btu/hr) and the size of
the factory installed orifices. NOTE: Natural Gas
furnaces may be equipped with one of three orifices.
WARNING:
Do not useTeflon tape or pipe joint compound
on the orifice threads. The hole in the orifice
may become blocked and cause fire, explosion,
property damage, carbon monoxide poisoning,
personal injury, or death.
iMPORTANT NOTES:
Before installing an orifice, check the face or side of
the orifice for the drill number to ensure that it is the
appropriate size.
To prevent cross threading, screw the orifices (7) into
the gas manifold assembly (5) by hand until snug,
then tighten with a wrench.
I. Install the appropriate LP/Propane orifices (7) into
the gas manifold assembly (5).
m. Remove the pressure regulator cap (Figure 35) from
the gas valve.
n. Invert the cap so that the letters facing up represent
the type of gas being used for the furnace.
NOTE: The cap is marked NAT on one end for
natural gas and LP on the other end for propane.
If converting to LP propane, make sure the LP end
is facing up when installed.
o. Replace the cap and tighten firmly.
p. Install the gas manifold assembly (5) back into the
burner assembly (6). Make sure the center of the
orifices are aligned with center of the burners.
q. Secure the manifold assembly (5) to the burner
assembly (6) with the four screws (4), removed in
step 1-h.
r. Reconnect the gas piping to the gas valve inlet (3).
s. Reconnect the wires to the gas valve terminals (2).
2. Measure the Supply Gas Pressure:
IMPORTANT NOTE: To obtain an accurate pressure
reading, turn off all gas appliances (i.e. Dryers, water
heaters, stoves, etc.) at their ON/OFF control or
individual gas valves.
a. Remove the inlet pressure plug (Figure 35) from
the INLET side of the gas valve with a 3/16 Allen
wrench.
b. Install a 1/8 NPT fitting, which is compatible with a
manometer or similar pressure gauge.
c. Connect the manometer or pressure gauge to the
inlet pressure tap.
d. Turn on all electrical power to the furnace.
e. Turn the main gas supply valve (on the outside of
the unit) to the ON position.
f. Start the furnace by adjusting the thermostat to
it's highest setting. Allow the furnace to run for 10
minutes.
g. Checkthe incoming gas line pressure. Propane gas
furnaces must be between 11.0"-14.0"W.C. Natural
gas installations must be between 4.5"-10.O"W.C. If
the pressure is not between these specified ranges,
contact your local gas supplier for adjustment.
h. Adjust the thermostat to it's lowest setting and allow
the unit to cycle off.
i. Turn the main gas supply valve (on the outside of
the unit) to the OFF position.
j. Turn off all electrical power to the furnace.
k. Disconnect the manometer or pressure gauge.
I. Remove the NPT fitting and reinstall the inlet
pressure plug. NOTE: To prevent cross threading,
hand tighten the plug first, then tighten with 3/16
Allen wrench.
Pressure Regulator,
Cap
ON/OFF
Knob
Inlet
Plug
Pressure Plug
Figure 35. Gas Valve =Top View
26