25
Model
Minimum Recommended Filter Size^
*MES960403BU 1 - 16 X 25 Side or Bottom
*MES960603BU 1 - 16 X 25 Side or Bottom
*MES960805CU 1 - 20 X 25 Bottom/2 - 16 X 25 Side Return
^ Larger filters may be used, filters may also be centrally located.
TABLE 7
Upright Installations
Depending on the installation and/or customer preference,
differing filter arrangements can be applied. Filters can be
installed in the central return register or a side panel external
filter rack kit (upflows). As an alternative a media air filter
or electronic air cleaner can be used as the requested filter.
Figure 33 shows possible filter locations.
AIR FLOW
SIDE RETURN
EXTERNAL FILTER
RACK KIT
(EITHER SIDE)
Possible Upright Upflow
Figure 33
Horizontal Installations
Filters must be installed in either the central return register or in
the return air duct work.
Startup Procedure & Adjustment
Furnace must have a 115 VAC power supply properly connected
and grounded. Proper polarity must be maintained for correct
operation. In addition to the following start-up and adjustment
items, refer to further information in
Operational Checks
section.
Drain Trap Priming
The drain trap
MUST
be primed prior to furnace startup. To
prime, fill both sides of the drain trap with water. This en
-
sures proper furnace drainage upon startup and prohibits the
possibility of flue gases escaping through the drain system.
Furnace Operation
Purge gas lines of air prior to startup. Be sure not purge lines into
an enclosed burner compartment. Follow NFPA 54, National
Fuel Gas Code 8.1.
Check for leaks using an approved chloride-free soap and
water solution, an electronic combustible gas detector, or
other approved method.
CAUTION
T
O
PREVENT
UNRELIABLE
OPERATION
OR
EQUIPMENT
DAMAGE
,
THE
INLET
GAS
SUPPLY
PRESSURE
MUST
BE
AS
SPECIFIED
ON
THE
UNIT
RATING
PLATE
WITH
ALL
OTHER
HOUSEHOLD
GAS
FIRED
APPLIANCES
OPERATING
.
Furnace Startup
1. Close the manual gas shutoff valve external to the furnace.
2. Turn off the electrical power to the furnace.
3. Set the room thermostat to the lowest possible setting.
4. Remove the burner compartment door.
NOTE:
This furnace is equipped with an ignition device
which automatically lights the burner. Do not try to light the
burner by hand.
5. Move the furnace gas valve manual con
trol to the OFF
position.
6. Wait five minutes then smell for gas. Be sure check
near the floor as some types of gas are heavier than
air.
7. If you smell gas after five minutes, immediately follow
the safety instructions in the
Safety Considerations
on
page 3 of this manual. If you do not smell gas after five
minutes, move the furnace gas valve manual control
to the ON position.
8. Replace the burner compartment door.
9. Open the manual gas shutoff valve external to the furnace.
10. Turn on the electrical power to the furnace.
11. Adjust the thermostat to a setting above room temperature.
12. After the burners are lit, set the thermostat to desired
temperature.
Furnace Shutdown
1. Set the thermostat to the lowest setting.
The integrated control will close the gas valve and
extinguish flame. Following a 30 second delay, the
induced draft blower will be de-energized. The
circulator blower will shut down when the time delay
expires (Time delay is selectable on all models).
2. Remove the burner compartment door and move the
furnace gas valve manual control to the OFF position.
3. Close the manual gas shutoff valve external to the
furnace.
4. Replace the burner compartment door.
Gas Supply Pressure Measurement
Gas Pressure Test
The line pressure supplied to the gas valve must be within the
range specified on Table 4 on page 21. The supply pressure
can be measured at the gas valve inlet pressure tap or at a
hose fitting installed in the gas piping drip leg. The supply
