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Installer's Guide
b. The pressure switch is closed.
c. The gas valve opens and the ignitor lights the burner.
d. Allow the thermostat to cycle on and off a few times in
Emergency Heat mode to check out the control system
and burner operation characteristics. For the *CONT802
and *CONT803 Comfort Controls if the call for heat lasts
longer than 10 minutes, these controls will transition to
high fire automatically.
3. With the burners operating, check the manifold pressure with
a manometer. Do not exceed recommended pressures.
4. Adjust the unit to obtain an air temperature rise with that
specified on the unit nameplate.
5. NOTE: For manifold pressures and orifice sizes for gas with
other BTU ratings, contact the local gas utility.
pressure should be 1.8 (low) to 3.5 (high) inches water
column (+0.1). Input must not exceed the value shown on
the nameplate.
6. Set the thermostat at the desired temperature setting and the
unit will function automatically.
Starting the Unit in the Gas Heating Mode
1. Check to make sure all grilles and registers are open and all
unit access doors are closed before start-up.
2. Purge the gas supply line of air by opening the union ahead
of the unit. When the odor of gas is detected, retighten the
union and wait five (5) minutes before proceeding.
3. Open the main gas valve(s) and turn on the unit power
supply.
4. Set the thermostat mode to Emergency Heat and adjust the
heating setpoint slightly above the room temperature.
5. The combustion blower motor should energize. The main
burners should light within 20-25 seconds. Initial start may be
delayed somewhat if the unit has not been purged and air is
trapped in the gas line.
NOTE: Blue smoke produced by the heat exchanger during
the initial burner firing is caused by a thin film of oil on the
surface of the heat exchanger. This oil will burn off quickly.
6.
Allow the thermostat to cycle on and off a few times at a
rate of not more than once every thirty (30) seconds.
Check both the control operation and the burner operating
conditions.
7.
Increase the heating setpoint significantly so that the
thermostat will transition to high fire automatically.
the *CONT802 and *CONT803 Comfort Controls, there is
a 10 minute delay before the transition occurs. Make the
following manifold pressure check on high fire.
MANIFOLD PRESSURE
1. Connect a manometer to the pressure tap at the outlet side
of the unit's gas valve. Read the manifold pressure with the
main burners firing. See figure 16, page 17.
2. If the manifold pressure reading does not match the value
indicated on the unit nameplate, the unit pressure regulator
must be adjusted as follows:
a. Remove the cover screw on the gas regulator located on
the front side of the unit's gas valve.
b. Turn the adjusting screw clockwise to increase manifold
pressure or counterclockwise to decrease manifold
pressure.
3. Check the temperature rise during furnace operation to
insure that it falls within the range specified on the unit
nameplate.
Page 24
4. If the temperature rise noted is outside of the specified limits,
adjust the indoor airflow to cause the temperature rise of the
heat exchanger to fall within the required range.
HEATING SHUT-DOWN
Set the comfort control to OFF or adjust the heating set point to
belowroom temperature.
Final Installation Checklist
Does the unit run and operate as described in the section on
Sequence of Operation in response to the room thermostat?
Are the condenser fan and indoor blower operating correctly
Manifold
with proper rotation and without undue noise?
Is the compressor operating correctly and has the system been
checked with a charging chart?
Has the voltage and running current been checked to deter
mine if it is within limits?
Has the thermostat been checked for calibration and the air
discharge grilles adjusted to balance the system?
Has the ductwork been checked for air leaks and
condensation?
Has the furnace manifold pressure been checked and
adjusted if necessary?
Has the heating air temperature rise been checked?
Has the unit been checked for tubing and sheet metal rattles?
Are there any other unusual noises to be checked?
Are all covers and panels in place and properly fastened?
Has the owner been instructed on the proper operation and
maintenance of the unit? Be sure to leave this manual with the
owner.
SEQUENCE OF OPERATION
The following description applies to the *CONT402. Some of
the operational differences of the *CONT802 and *CONT803
are described at the end of this section.
The following description applies to non-restricted mode.
Restricted operation will be identical except that transitions
from and to second stage (heat pump) heating to and from
For
third stage (gas) heating can occur, not necessarily as
a result of building load and equipment capacity, but as
determined by the
selected by the installer at the indoor thermostat (see
Restricted Mode described on page 19).
Call for 1st stage heating (heat pump):
With the room thermostat set to HEAT and the fan set to AUTO,
NO power is supplied from the room thermostate "O" terminal
to the unit switchover valve coil (SOV) and the "O" terminal on
the ECMC board. This leaves the switch-over valve (SOV) in
the normal position for heating and is the signal for the (ECMC)
to run at indoor fan speeds designed for heating. On a call for
heating, power is supplied to the unit from the room thermostat
(Y1) and (G) terminal. (Y1) provides power to the compressor
contactor (CC), the defrost control (DFC) and the
outdoor temperature changeover point
electronically
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