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3.
Measure the time (in seconds) required for the gas
meter to complete one revolution.
4.
Convert the time per revolution to cubic feet of gas
per hour using Table 11.
5.
Multiply the gas flow rate in cubic feet per hour by the
heating value of the gas in Btu per cubic foot to
obtain the firing rate in Btu per hour. Example:
• Time for 1 revolution of a gas meter with a 1 cubic
foot dial = 40 seconds.
• From Table 11 read 90 cubic feet per hour of gas.
• Heating value of the gas (obtained from gas
supplier) = 1040 Btu per cubic foot.
• Firing rate = 1040 x 90 = 93,600 Btuh.
6.
Adjustments to the firing rate can be made by
adjusting the gas manifold pressure. See the High
Altitude Application section for additional information
of firing rate at elevations above 2000 ft.
The manifold pressure must be set to the appropriate value
for your installation. Refer to either Table 6 for natural gas or
Table 7 for LP/propane gas to verify the manifold pressure
setting required for your particular installation. To adjust the
manifold pressure, remove the regulator cap and turn the
adjusting screw clockwise to increase pressure or counter-
clockwise to reduce pressure. Replace the regulator cap
after adjustments are complete.
CAUTION:
!
Do not re-drill the burner orifices. If the orifice
size must be changed, use only new orifices.
Connect
R & W
For
Heating
Only
Room
Thermostat
NOTE: The "Y"
terminal on the
UTEC control board
must be connected
to the thermostat
for proper cooling
mode operation.
FIELD WIRING
Low Voltage
Connections
Figure 23. Low Voltage Field, Four-wire Heating/Cooling Applications
Configuring the Blower
The variable speed blower kit is equipped with a micropro-
cessor-controlled variable speed motor that is pre-pro-
grammed to deliver optimum airflow in a variety of condi-
tions and system configurations. Before operation, the
variable speed blower kit must be configured to match the
unit with the system, system options, and climatic condi-
tions. With the variable speed blower kit installed and
configured properly, the furnace will respond directly to
gradually change speed in response to changes in system
variables such as the thermostat settings, duct static,
filter, etc. The variable speed blower kit is configured by
setting the 7 switches located on the motor control board
as described below.
!
The variable speed blower kit has been designed
to give the installer maximum flexibility to
optimize system performance, efficiency, and
comfort. Because there are so many ways to
configure the kit it is important to read and
follow these instructions carefully.
Selecting Heat Airflow
The heating airflow is selected by setting switches 5, 6 ,
and 7 as displayed on Figure 21. Refer to Table 2 and select
a nominal rise based on the furnace nominal efficiency and
input. Follow the table column up to find the switch setting
and nominal air-flow. Be sure that the selected rise is within
the specification of the furnace as shown on the furnace
rating label. For single stage cooling, follow the high airflow
column.
A/C Condensing Unit
Condensing Unit
Control Box
Blower Off
COM
Timing
3 Amp
Fuse
24 V
Flame Signal Light
(Yellow)
Status Light
(Red)
9
6
3
8
5
2
7
4
1
Neutrals
Unused Motor Leads
6 3
5 2
4 1
IMPORTANT:
25
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