15
(1.) Thermostat closes circuit R to G--The Blower
runs at continuous fan airflow.
b. COOLING MODE
(1.) If indoor temperature is above temperature set
point and humidity is below humidity set point,
thermostat closes circuits R to G, R to Y/Y2 and
R to O--The unit delivers single speed cooling
airflow.
c. COOLING MODE--DEHUMIDIFICATION
(1.) If indoor temperature is above temperature set
point and humidity is above humidity set point,
thermostat or Thermidistat closes circuits R to G,
R to Y/Y2, R to O and humidistat or Thermidistat
opens R to DH--The unit delivers airflow which is
approximately 80 percent of the nominal cooling
airflow to increase the latent capacity of the
system.
d. COOLING MODE--SUPER DEHUMIDIFY
OPERATION (SEE QUICK REFERENCE GUIDE)
NOTE: The indoor control used, such as a Thermidistat, must be
capable of providing Super Dehumidify operation mode and
control must be configured as outlined in its installation
instructions. Consult indoor control literature to determine if
control is capable of providing Super Dehumidify inputs and for
configuration instruction.
(1.) If the indoor temperature is below the temperature
set point and the humidity is above the humidity
set point, the Thermidistat closes circuit R to O,
opens circuits R to DH and R to G, and closes
circuit R to Y/Y2. If circuit R to G is closed
(24--v.), the motor will deliver airflow at the full
cooling or cooling plus dehumidify mode
requested value. If circuit R to G is open (0--v.)
for Super Dehumidify mode, the motor delivers
reduced airflow to maximize the humidity
removal of the system while minimizing over
cooling.
e. GAS HEATING MODE
(1.) Thermostat closes circuit R to W/W1--The unit
delivers the selected gas heat airflow. The IGC
will control a 45 sec. blower “On” delay and a 45
sec. “Off” delay.
Step 3 — START--UP HEATING AND MAKE
ADJUSTMENTS
UNIT COMPONENT DAMAGE HAZARD
Failure to follow this caution may result in damage to the unit
being installed.
Complete the required procedures given in the Pre--Start--Up
section before starting the unit. Do not jumper any safety
devices when operating the unit.
!
CAUTION
Make sure that burner orifices are properly aligned. Unstable
operation may occur when the burner orifices in the manifold are
misaligned.
Follow the lighting instructions on the heating section operation
label (located inside the burner or blower access door) to start the
heating section.
NOTE: Make sure that gas supply has been purged, and that all
gas piping has been checked for leaks.
CHECK HEATING
CONTROL
Start and check the unit for proper cooling control operation as
follows (see furnace lighting instructions located inside burner or
blower access panel):
1. Place room thermostat SYSTEM switch in the HEAT
position and the fan switch is placed in AUTO position.
2. Set the heating temperature control of the thermostat
above room temperature.
3. The induced--draft motor will start.
4. After a call for heating, the main burner should light
within 5 sec. If the burners do not light, there is a 22--sec.
delay before another 5--sec. try. If the burners still do not
light, this sequence is repeated. If the burners do not light
within 15 minutes from the initial call for heat, there is a
lockout. To reset the control, break the 24--v power to W.
5. The evaporator fan will turn on 45 sec. after the flame has
been established. The evaporator fan will turn off 45 sec.
after the thermostat has been satisfied.
CHECK GAS
INPUT
Check gas input and manifold pressure after unit start--up (See
Table 3). If adjustment is required proceed as follows:
S The rated gas inputs shown in Table 3 are for altitudes from
sea level to 2000 ft above sea level. These inputs are based on
natural gas with a heating value of 1050 Btu/ft
3
at 0.65 specific
gravity, or propane gas with a heating value of 2500 Btu/ft
3
at
1.5 specific gravity.
S For elevations above 2000 ft, reduce input 4% for each 1000
ft above sea level.
S When the gas supply being used has a different heating value
or specific gravity, refer to national and local codes, or contact
your distributor to determine the required orifice size.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in reduced unit and/or
component life.
Do Not redrill an orifice. Improper drilling (burrs,
out--of--round holes, etc.) can cause excessive burner noise
and misdirection of burner flame. Replace with correct sized
orifices.
!
CAUTION
ADJUST GAS INPUT
The gas input to the unit is determined by measuring the gas flow
at the meter or by measuring the manifold pressure. Measuring
the gas flow at the meter is recommended for natural gas units.
The manifold pressure must be measured to determine the input
of propane gas units.
Measure Gas Flow (Natural Gas Units)
Minor adjustment to the gas flow can be made by changing the
manifold pressure. The manifold pressure must be maintained
between 3.4 and 3.6 in. wc. If larger adjustments are required,
change main burner orifices following the recommendations of
national and local codes.
NOTE: All other appliances that use the same meter must be
turned off when gas flow is measured at the meter. Proceed as
follows:
1. Turn off gas supply to unit.
2. Remove pipe plug on manifold (See Fig. 16) and connect
manometer. Turn on gas supply to unit.
3. Record number of seconds for gas meter test dial to make
one revolution.
48XP
To Next Page
Loading...
