AERCO C-More Controls - Manual (Page 32)

C-MORE CONTROL PANEL OPERATION
5.3.3.1 Reset Ratio
Reset ratio is an adjustable number from 0.1 to
9.9. Once adjusted, the supply header
temperature will increase by that number for
each degree that the outside air temperature
decreases. For instance, if a reset ratio of 1.6 is
used, for each degree that outside air
temperature decreases, the supply header
temperature will increase by 1.6 degrees.
5.3.3.2 Building Reference Temperature
This is a temperature from 40°F to 230°F. Once
selected, it is the temperature that the system
references to begin increasing its temperature.
For instance, if a reset ratio of 1.6 is used, and
we select a building reference temperature of
70°F, then at an outside temperature of 69°F,
the supply header temperature will increase by
1.6° to 71.6°F.
5.3.3.3 Outdoor Air Temperature Sensor
Installation
The outdoor air temperature sensor must be
mounted on the North side of the building in an
area where the average outside air temperature
is expected. The sensor must be shielded from
the sun's direct rays, as well as direct
impingement by the elements. If a cover or
shield is used, it must allow free air circulation.
The sensor may be mounted up to two hundred
feet from the unit. Sensor connections are
made inside the Input/Output (I/O) Box at the
terminals labeled OUTDOOR SENSOR IN and
SENSOR COMMON using shielded 18 to 22
AWG wire. A wiring diagram is provided on the
cover of the I/O Box. Refer to Section 2 of
Operation & Maintenance Manual GF-109 (KC
Series) or GF-110 (Benchmark Series) for
additional wiring information.
5.3.3.4 Indoor/Outdoor Startup
1. Refer to the indoor/outdoor reset ratio charts
in Appendix C.
2. Choose the chart corresponding to the
desired building reference temperature.
3. Go down the left column of the chart to the
coldest design outdoor air temperature
expected for your area.
NOTE:
A design engineer typically provides design
outdoor air temperature and supply header
temperature data
4. Once the design outdoor air temperature is
chosen, go across the chart to the desired
supply header temperature (setpoint) for the
design temperature chosen in step 3.
5. Next, go up that column to the Reset Ratio
row to find the corresponding reset ratio.
6. Access the Configuration Menu and scroll
through it until the display shows Bldg Ref
Temp (Building Reference Temperature)
.
7. Press the CHANGE key. The display will
begin to flash.
8. Use
the ▲ and ▼ arrow keys to select the
desired building reference temperature.
9. Press
ENTER to save any changes.
10. Next, scroll through the Configuration Menu
until the display shows Reset Ratio.
11. Press the CHANGE key. The display will
begin to flash.
12. Use the ▲ and ▼ arrow keys to select the
reset ratio determined in step 5.
13. Press ENTER to save the change.
Refer to paragraph 2.2 for detailed instructions
on menu changing.
5.3.4 Direct Drive Modes
The boiler’s fire rate can be changed by a
remote signal typically sent from an energy
management system. The Direct Drive modes
are driven by current or voltage signals in the
following ranges:
4 - 20 mA/1 - 5 Vdc
0 - 20 mA/0 - 5 Vdc
The factory default setting is 4 - 20 mA/1 - 5
Vdc. In this mode of operation, a 4 to 20mA
signal, sent by an energy management system,
is used to change the boiler’s fire rate from 0%
to 100%. The 4 mA/1Vdc signal is equal to a 0%
fire rate while a 20 mA /5Vdc signal is equal to a
100% fire rate. When a 0-20 mA/0-5 Vdc signal
is used, zero is equal to a 0% fire rate.
In addition to the current and voltage signals
described above, the Direct Drive mode can also
be driven by a RS-485 Modbus Network signal
from an EMS or BAS.
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