650.75-N4U
035-14370-000
28
Unitary Products Group
3.
System start-up will occur as follows:
a.
The induced draft blower motor will start and oper-
ate on low speed. Shortly after venter start-up, the
hot surface igniter will glow for about 17 seconds.
b.
The ignition module will energize (open) the main
gas valve on low fire for seven seconds.
c.
After flame is established, the supply air blower will
start in about 30 seconds.
NOTE:Burner ignition may not be satisfactory on first start-up
due to residual air in line.
4.
With furnace in operation, paint the pipe joints and valve
gasket lines with a rich soap and water solution, Bubbles
indicate a gas leak. Take appropriate steps to stop the
leak. If the leak persists, replace the component.
GAS VALVE OPERATION
The manual valve knob is a two-position (ON-OFF) type. To
turn the valve ON, rotate knob clockwise or counterclockwise
to line up the word ON on the knob with the indicator on the
cover casting (Refer to Figure 36).
CHECKING GAS INPUT (NATURAL GAS)
NOTE:Front door of burner box must be secured when
checking gas input.
1.
Turn off all other gas appliances connected to the gas
meter.
2.
With the furnace turned on, measure the time needed for
one revolution of the hand on the smallest dial on the
meter. A typical domestic gas meter usually has a 1/2 or
1 cubic foot test dial.
3.
Using the number of seconds for each revolution and the
size of the test dial increment, find the cubic feet of gas
consumed per hour, (Refer to Table 9 on page 29).
To find the BTUH input use the following formula:
Cu. Ft. Gas x meter correction factor x Gas BTU Content =
BTU Per Hour Input
The gas meter is affected by both the temperature and also
the barometric pressure. The meter should be correct at 60°
F, and 30.0" barometric pressure. At all other conditions it will
be inaccurate, although the correction factor is easily calcu-
lated. Higher temperatures (over 60° F) will speed up the
meter and make it read high.
Temperatures under 60° F will slow it and make it read low.
The barometric pressure above 30.0" will slow the meter and
below 30.0" speed up the meter. At some conditions the
meter may be off significantly. an error of
+5% is not uncom-
mon. The gas meter correction factor is calculated as follows:
Example 1: 28.9" Barometric Pressure, 80° F
Contact your gas supplier for actual BTU content of the gas.
DO NOT omit this test! Never use a flame to check
for gas leaks.
FIGURE 36 : GAS VALVES -
(TOP) WHITE-RODGERS 36E24
(BOTTOM) HONEYWELL VR8205
(approved for field replacement)
(Barometric Pressure) x 520
= Meter Correction Factor
(Temperature F + 460) x 30
(28.9) x 520
= 15028
= .928 Correction Factor
(80 + 460) x 30
= 16200
Wiring
Terminals
Outlet
Main
Regulator
Adjust
Wrench
Boss
ON - OFF Switch
Inlet
Outlet
Pressure
Tap
