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Installer’s Information Manual
11. Remove jumper wire from 24-volt terminal strip.
Remove pressure taps and seal holes in ductwork.
SECTION 20. MEASURING AIR
TEMPERATURE RISE
You will need 2 thermometers with 1-degree resolution
capable of reading up to 175 degrees F.
Air temperature rise (supply air temperature minus retu rn
air temperature) must be within allowable air-temperature
rise range specified on fu rnace rating plate and in Table 9.
Follow this procedure:
1. Open supply-air registers and retu rn air grilles. Make
sure registers and grilles are free of obstruction from
rugs, carpets, drapes or fu rniture.
2. Set balancing dampers in supply duct system.
3. Check ductwork for obstructions or leaks.
4. Make sure filters are clean and in place.
5. Make sure that blower speed taps are set for proper
heating and cooling. Refer to Section 18, "Adjusting
Blower Speed." Heating speed should be set
according to Table 9. Cooling speed should be set to
meet cooling equipment requirements. See Table 10
for cooling airflow capacities at 0.5 inch W.C.
6. Place one thermometer in supply air plenum
approximately 2 feet from furnace. Locate
thermometer tip in center of plenum to ensure proper
temperature measurement.
7. Place second thermometer in retu rn air duct
approximately 2 feet from furnace. Locate
thermometer tip in center of duct to ensure proper
temperature measurement.
8. Set room thermostat on highest temperature setting.
Operate furnace 6 minutes. Record supply air and
return air temperatures.
9. Calculate air temperature rise by subtracting retu rn air
temperature from supply air temperature.
??
If air temperature rise is above temperature rise
range s pecified in Table 9, fu rnace is overfired or
has insufficient airflow. Check gas input following
the instructions in Section 14, "Checking Gas
Input Rate." If air temperature rise is still above
temperature rise range specified, more airflow is
needed. Change blower heating speed to a
higher setting following instructions in Section 18,
"Adjusting Blower Speed."
??
If air temperature rise is below temperature rise
range specified in Table 9, fu rnace is underfired
or has too much airflow. Check gas input
following the instructions in Section 14, "Checking
Gas Input Rate." If air temperature rise is still
below temperature rise range specified, less
heating airflow is needed. Change blower
heating speed to a lower setting following
instructions in Section 18, "Adjusting Blower
Speed."
??
After making adjustments, you must check air
temperature rise to verify that resulting air
temperature rise is within allowable range. If air
temperature rise is still outside temperature rise
range specified in Table 9, check duct system
design with a qualified heating engineer. It may
be necessary to re-size duct work. Recheck air
temperature rise after revising duct systems.
10. Set room thermostat to desired setting.
11. Remove thermometers and seal ductwork holes.
SECTION 21. CHECKING
CONTROLS
Before leaving work site, check to see that all controls are
functioning properly.
You will need a 0 to 15 inch water manometer with 0.1 inch
resolution and a 1/8" NPT manual shut-off valve.
Follow this procedure:
1. Turn off electricity at electrical disconnect switch next
to furnace.
2. Remove three screws holding burner access panel in
place. Remove burner access panel.
3. Turn gas control switch to OFF position.
4. Connect a manometer to gas control outlet (manifold)
pressure tap.
5. Set room thermostat to its highest temperature.
6. Turn on electricity at electrical disconnect switch
located next to furnace.
7. Diagnostic light on Fan Timer should be on and cycling
bright-dim -bright-dim...
8. Draft inducer should run and pilot igniter should glow
but pilot burner should not light. Manifold pressure
should remain at zero.
9. Turn gas control switch to ON position.
10. Pilot burner should light and ignite main burners. It
may take several minutes to purge gas line before pilot
burner lights. Wait 30 seconds after main burner
ignition for main blower to start.
11. Cycle electrical disconnect switch next to furnace on
and off. Watch at least three ignition cycles. Pilot
should ignite main burners smoothly.
12. Burner flames should look the same with circulation
blower on and off.
13. Remove manometer from gas control and replace
outlet pressure tap
14. Use a commercial soap solution made to detect leaks
and check all gas piping connections. Bubbles indicate
gas leakage. Seal all leaks before proceeding.
15. Replace burner access panel using three screws
removed in step 2.
16. Set room thermostat to desired setting.
