Never purge a line into a combustion chamber. Never use
matches, candles, flame, or other sources of ignition for the
purpose of checking leakage. Use a soap-and-water solution
to check for leakage. Failure to follow this warning could
result in a fire, explosion, personal injury, or death.
Many soaps used for leak testing are corrosive to certain
metals. Piping must be rinsed thoroughly with clean water
after leak check has been completed.
Step 4—Operational Checkout
This furnace is equipped with an automatic hot surface pilot
ignition control and does not require lighting of a pilot for furnace
operation.
Do not attempt to manually light pilot. Failure to follow this
warning can lead to electrical shock which could result in
bodily harm.
The automatic gas valve controls the flow of gas to both the pilot
and main burners. The manual valve built into automatic valve
body has 2 positions: OFF and ON.
To shut off gas manually, turn knob from ON to OFF position.
When in OFF position, main burners and pilot are extinguished.
After duct work connections have been made, gas piping and
electrical wiring completed, and furnace had been properly vented,
unit should be started and adjusted for proper operation. Check off
the following items as they are completed.
1. Make sure all electrical power is off.
2. Check all wiring using proper wiring diagram on inside of
control box cover.
3. Turn on electrical power to unit.
4. Turn manual gas shutoff valve to ON position.
5. Set thermostat above room temperature.
6. The hot surface ignitor should heat up to an orange glow and
ignite pilot. If flame sensor detects a proper flame, main
burners will ignite. If main burners do not ignite, see Adjust
Pilot Flame section below.
7. When main burners ignite, proceed to Set Gas Input Rate
section.
Step 5—Adjustments
ADJUST PILOT FLAME
Pilot assembly should be located as shown in Fig. 13. Adjust pilot
flame to envelop the flame sensor for a distance of 3/8 to 1/2 in.
(See Fig. 14.) The adjusting screw for pilot flame is located on
main gas control. (See Fig. 15.)
SET GAS INPUT RATE
Never set furnace input rate above that shown on rating plate.
Failure to follow this warning could lead to premature heat
exchanger failure and a hazardous furnace operating condi-
tion and result in serious bodily injury or loss of life.
There are 2 methods of adjusting gas input rate. The preferred
method is by using Table 5 and item 1. The second method is by
clocking the gas meter and using item 2. Item 2 must be used for
altitudes above 2000 ft.
1. Determine natural gas orifice size and manifold pressure for
correct input using Table 5.
a. Obtain average yearly heat value for local gas supply.
b. Obtain average yearly specific gravity for local gas supply.
c. Verify the furnace model. Table 5 can only be used for
model 58EFB Furnaces.
d. Find natural gas heat value and specific gravity in Table 5.
e. Follow heat value line and specific gravity line to point of
intersection to find orifice size and manifold pressure
settings for proper operation at given natural gas condition.
f. Check and verify orifice size in furnace. NEVER ASSUME
THE ORIFICE SIZE. ALWAYS CHECK AND VERIFY.
EXAMPLE:
Heat value = 1025 Btu/cu ft
Specific gravity = 0.62.
Therefore: Orifice No. 40 or 41*
Manifold Pressure 3.3 or 3.5 in. wc
* The furnace is shipped with No. 42 orifices. In this
example all main burner orifices must be changed and
manifold pressure must be adjusted.
g. Proceed to item 3 to adjust manifold pressure.
Fig. 13—Position of Pilot Assembly to Burner
A96078
Fig. 14—Position of Pilot Flame to Flame Sensor
A96077
FLAME
SENSING
ROD
HOT
SURFACE
IGNITOR
3
⁄
8
″
TO
1
⁄
2
″
14