52
Marvair GAA A/C w/Gas Heat I&O Manual
06/2023 Rev.5
5. Remove the screws holding the manifold pipe assembly to the burner assembly.
6. Remove manifold.
7. Loosen and remove the Natural Gas Orifices and remove from the manifold.
8. Install LP gas orifices provided with the kit.
9. Open the Gas Valve Regulator conversion kit and follow the instructions provided for conversion of
the gas valve regulator. Be sure to apply the label indicating that the valve has been converted from
Natural Gas to LP gas.
10. Secure the manifold burner assembly to the burner assembly with the four screws. Be sure the
orifices are aligned with the opening on each burner.
11. Reconnect the gas supply pipe, using pipe joint compound resistant to LP gas on the pipe threads, to
the gas valve. Tighten the union fitting.
12. Reconnect wires to the gas valve following the wiring diagram provided on the unit.
13. Turn on the gas supply at the manual shut off valve.
14. Carefully leak check union fitting and connection at gas valve using soap suds or a liquid detergent
to each joint. Bubbles indicate a leak. Correct even the smallest leak immediately. Do NOT use a
flame to check for leaks.
15. Turn Gas Valve to OFF.
16. With gas valve OFF, connect the manometer to manifold pressure tap on outlet ( 1 / 8” NPT ) of the
gas control valve. Use a manometer with a 0” to 12” water column range.
Figure 9. Gas Valve Manifold Pressure Tap
17. Turn gas ON. Operate furnace by using a jumper wire on the “10” and “4” thermostat connections
on the low voltage board. The board is located in the electrical compartment in the unit.
18. Regulator pressure may be adjusted by removing the plastic cap on top of gas valve, as shown below.
Turn the “HI” adjustment screw counterclockwise to decrease the manifold pressure and clockwise
to increase the manifold pressure. Set the manifold pressure to 10.0” w.c. for LP gas. Only adjust the
setting marked “HI”. A 3 / 32” Allen Key is required for adjustment.
19. When the manifold pressure is properly set, replace the adjustment screw cover on the gas control
valve.
20. Remove manometer and replace the 1 / 8” NPT tapping.
