19
Removing The Burner Orifices
1. Set the thermostat to the OFF position, or its lowest
temperature setting.
2. Shut OFF the gas supply at the manual shutoff valve
located outside of the appliance.
3. Turn off all electrical power to the appliance.
4. Remove the door from the burner box by removing 6
screws.
5. Turn the gas valve ON/OFF knob to the OFF position.
See Figure 14.
6. Remove the wires from the terminals of the gas valve.
7. Remove the supply gas piping from the gas valve inlet.
8. Carefully remove four screws securing the gas manifold
assembly to the burner assembly.
9. Set the screws aside and remove the gas manifold
assembly from the appliance.
10. Carefully remove the burner orifices from the gas
manifold assembly.
11. Read the rating plate affixed to the appliance to
determine its rated input (Btu/hr) and the size of the
factory installed orifices.
IMPORTANT: Before installing an orifice, check
the side or face of the orifice for the drill number
to ensure that it is the appropriate size.
12. Install the appropriate LP/Propane gas burner orifices
into the gas manifold assembly.
NOTE:
The orifices are
included with the furnace.
To prevent cross threading,
hand tighten the orifices into the gas manifold assembly
until snug, then tighten with a wrench.
13. Unscrew the gas valve pressure regulator cap marked
NAT. Invert the cap so LP faces up. Reinstall the cap
and tighten until snug. Make sure LP is visible after
conversion.
Gas Pressure Verification
Measuring the Supply Gas Pressure
1. Turn OFF the gas supply at the manual valve located
on the outside of the unit.
2. Using a 3/16” Allen wrench, remove the plug from the
inlet pressure tap (INLET side of gas valve). See Figure
13 (page 18).
3. Install an 1/8” NPT pipe thread fitting, that is compatible
with a Manometer or similar pressure gauge.
4. Connect the Manometer or pressure gauge to the Inlet
Pressure Tap.
5. Turn ON the main gas supply at the manual valve.
6. Check and adjust the incoming gas line pressure to
11.0-14.0 inches Water Column for LP/Propane gas.
7. Turn OFF the gas supply at the manual valve.
8. Disconnect the Manometer or pressure gauge.
9. Remove the NPT fitting and reinstall the INLET pressure
tap plug. Hand tighten the plug first to prevent cross-
threading. Tighten with 3/16 Allen wrench.
Figure 14. Orifice Removal
Burner Box
Orifice
(X4)
Gas Valve
Gas Manifold
Burner Box
Door
(X4)
(X6)
WARNING:
Do not use Teflon 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.
14. Reinstall the gas manifold assembly to the burner
assembly with the 4 screws, that were removed earlier.
NOTE:
It is important that the center of the orifices
are aligned with the center of the burners.
15. Reinstall the burner box door with the 6 screws that
were removed earlier in step 4.
16. Reconnect the gas piping to the gas valve inlet.
17. Reconnect the wires to the gas valve terminals.
