15
C
B
VL & VM
NOTE:
Do
NOT
operate sheave with flange projecting beyond
the hub end.
GAS SYSTEM CHECK
Pre-Operation Checks
1. Close the manual gas valve external to the unit.
2. Turn off the electrical power supply to the unit.
3. Set the room thermostat to its lowest possible setting.
4. Remove the heat exchanger door on the side of the unit
by removing screws.
5. This unit is equipped with an ignition device which
automatically lights the main burner. DO NOT try to light
burner by any other method.
6. Move the gas control valve switch to the OFF position. Do
not force.
7. Wait five minutes to clear out any gas.
8. Smell for gas, including near the ground. This is important
because some types of gas are heavier than air. If you have
waited five minutes and you do smell gas, immediately
follow the warnings on page 3 of this manual. If having
waited for five minutes and no gas smell is noted, move
the gas control valve switch to the ON position.
9. Replace the heat exchanger door on the side of the unit.
10. Open the manual gas valve external to the unit.
11. Turn on the electrical power supply to the unit.
12. Set the thermostat to desired setting.
G
AS
S
UPPLY
P
RESSURES
& R
EGULATOR
A
DJUSTMENTS
S
HOULD
OVERHEATING
OCCUR
OR
THE
GAS
SUPPLY
FAIL
TO
SHUT
OFF
,
TURN
OFF
THE
MANUAL
GAS
SHUTOFF
VALVE
EXTERNAL
TO
THE
UNIT
BEFORE
TURNING
OFF
THE
ELECTRICAL
SUPPLY
.
WARNING
T
O
AVOID
PROPERTY
DAMAGE
,
PERSONAL
INJURY
OR
DEATH
,
DO
NOT
FIRE
GAS
UNIT
WITH
FLUE
BOX
COVER
REMOVED
.
WARNING
NOTE:
Except during brief periods when gas pressures are being
measured by qualified service personnel, the furnace access panel
must always be secured in place when the furnace is in operation.
An inspection port in the access panel is provided to monitor the
flame.
The first step in checking out the gas-fired furnace is to test the
gas supply piping to the unit for tightness and purge the system of
air using methods outlined in the latest edition of the National
Fuel Gas Code ANSI Z223.1. Verify that the disconnect switch is in
the “OFF” position. A soapy water solution should be used to check
for gas leaks. Since the unit is subject to considerable jarring dur-
ing shipment, it is extremely important that all gas connections
and joints be tested for tightness. Gas piping downstream from
the unit inlet should be checked for leaks during the subsequent
sequence check.
The supply gas pressure should be adjusted to 7.0" w.c. on natural
gas and 11.0" on LP gas with the gas burners operating. If there is
more than one unit on a common gas line, the pressures should
be checked with all units under full fire. A supply pressure tap is
provided on the upstream side of the gas valve. A manifold pres-
sure tap is provided on the gas valve. The normal manifold pres-
sure for full input is 3.5" w.c. on natural gas and 9.5" w.c. for pro-
pane gas. Low fire natural gas 2.0” w.c., 6.0” low fire propane gas.
Minimum gas supply pressure is 5.5" w.c. for natural gas and 11.0"
for propane gas. In order to obtain rating, gas supply pressure must
be 11.0" w.c. for propane gas.
The pressure regulator on LP gas models is adjusted for 9.5" w.c.
manifold pressure and is intended to prevent over-firing only. Do
not attempt adjustment of the built-in pressure regulator unless
the supply pressure is at least 7.0" w.c. on natural gas or 13.0" w.c.
on propane gas. Check the location of the ignition electrode and
the flame sensor for correct gap setting.
FLAME
SENSOR
Flame Sensor and Ignition Electrode Location
