Unit installation

035-20507-001 Rev. A (0804)
Unitary Products Group 3
TEST AND ADJUSTMENTS
The following tests must be performed at the time of conver-
sion following completion of the installation.
1. Connect a manometer to the pressure tap on both the
inlet and outlet side of the gas valve. Connect a power
supply and a propane gas supply to the unit, if not
already connected.
2. Turn on the propane gas supply and bleed air from the
gas supply lines at a point as close to the inlet of the gas
valve as is practical.
3. Turn the gas valve control switch to the “ON” position.
4. Make sure unit electrical disconnect switch is in the OFF
position.
5. Set the room thermostat to call for heat.
6. Turn unit electrical disconnect switch to ON. The com-
bustion blower should start and the hot surface igniter
should start glowing.
7. After air has been purged from the gas supply line, igni-
tion should occur. Shortly after ignition, the manifold and
gas inlet pressures can be checked on the manometers.
Main burner ignition may be delayed on the first ignition
cycle due to air in the gas manifold.
8. Adjust the manifold pressure on low fire by turning the 3/
32" set screw below the low adjustment seal screw either
clockwise (to increase) or counterclockwise (to
decrease) as required until the manometer reads 4.0"
w.c. Using this same procedure, adjust the manifold
pressure on high fire to 10.0" w.c. Refer to Figure 1 for
location of low and high fire set screws. These settings
will result in a propane gas input which is the same as
the natural gas input found on the unit rating plate. When
adjustments are complete, replace adjustment seal
screws.
9. The supply gas must be supplied to the unit as a pres-
sure of 11-13.9" w.c. Using the manometer, verify that
the supply pressure is within the range specified above.
If required, adjust the incoming regulator spring so that
the pressure falls within the range.
10. Observe several ignition cycles. All main burners must
ignite without delayed ignition or burning at the orifices. If
delayed ignition is observed, verify that the igniter is
properly mounted (not loose or crooked on bracket, and
that bracket screws are not loose).
11. If burning at the orifices, excessive yellow tipping, or
excessive noise is observed during any phase of main
burner operation, correct unit operation.
Table 2:
Altitude/Propane (LP) Gas Heating Value Orifice Selection
PROPANE GAS HEATING VALUE
(MANIFOLD PRESSURE 10.0" W.C.)
PROPANE
ORIFICE
@ SEA LEVEL
RECOMMENDED ORIFICE
ALTITUDE (FT. ABOVE SEA LEVEL)
0 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000
2516
BTU/CU.FT.
54 54 54 55 55 55 55 55 56 56 56
55 55 55 55 55 56 56 56 56 56 57
56 56 56 56 57 57 57 58 59 59 60
Make sure both gas and power supplies are shut off
before proceeding.
On 90+ AFUE models, refer to unit installation
instructions for proper procedure for connecting
manometer to furnace.
INLET GAS PRESSURE MUST BE AT 11-13.8" WC AT
FURNACE.
SET MANIFOLD PRESSURE AT 4.0" WC FOR LOW
FIRE.
SET MANIFOLD PRESSURE AT 10.0" WC FOR HIGH
FIRE.
On 90+ AFUE furnaces, the gas valve regulator seal
screws must be in place to determine final gas pres-
sure setting.
FIGURE 1: Gas Valve
INLET
WRENCH
BOSS
INLET
PRESSURE
PORT
ON OFF
SWITCH
LOW STAGE REGULATOR
ADJUSTMENT
OUTLET
OUTLET
PRESSURE
PORT
VENT
PORT
HIGH STAGE REGULATOR
ADJUSTMENT