AERCO KC1000 Boiler equipped with Mod-Box Controller - Manual (Page 29)

MODE OF OPERATION
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SECTION 5- MODE OF OPERATION
The following is a detailed description of the
KC1000’s six modes of operation. Each unit is
shipped from the factory tested and configured in
the mode of operation it was ordered. All
temperature related parameters are at factory
defaults and work well in most applications.
However, it may be necessary to change certain
parameters to customize the unit to the system.
A complete listing and description of temperature
related parameters is in Appendix A. Factory
defaults are located in Appendix E. After reading
this section, parameters can be customized to
suit the needs of the application.
5.1 INDOOR/OUTDOOR RESET MODE
This mode of operation is based on outside air
temperatures. As the outside air temperature
decreases, the supply header temperature
increases and vice versa. For this mode of
operation, it is necessary to install an outside air
sensor as well as select a building reference
temperature and a reset ratio.
5.1.1 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.
5.1.2. BUILDING REFERENCE
TEMPERATURE
Building reference temperature is the
temperature that the inside of the structure is to
be maintained. This is a number from 0 to 300
and once chosen, 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 choose a building reference
temperature of 70 degrees, then at 69 degrees
outside temperature, the supply header
temperature will increase by 1.6 degrees to 71.6
degrees.
5.1.3 OUTDOOR AIR SENSOR
INSTALLATION
When mounting the Outdoor Air Temperature
Sensor, it should be mounted on the north side
of the building in an area where the average
outside air temperature is expected. The sensor
should 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.
The outdoor air sensor must be connected to the
external field wiring box located under the control
panel on the left-hand side of the unit.
Connections are to be made to terminals 16 and
15.
5.1.4 INDOOR / OUTDOOR STARTUP
1. Refer to the indoor/outdoor reset ratio charts
in Appendix D.
2. Choose the building reference temperature
that the structure is to be maintained.
3. Go down the left column of the chart to the
coldest degree day reachable in that area
NOTE:
Degree day and supply water temperature
data are typically provided by a design
engineer or your local AERCO
representative.
4. Once the degree day is chosen go across
the chart to the desired supply header
temperature for the degree day chosen in
step three.
5. Now go up that column to the reset ratio row
to find the reset ratio.
6. Access the secondary menu of the
temperature controller and then scroll
through it until the display shows REFT. This
is the building reference temperature.
7. Use
the ⇑ ⇓ arrow keys to set the desired
building reference temperature.
8. Press ENTER to accept any changes.
9. Now scroll through the secondary menu until
it displays RR. This is the reset ratio.
10. Use the
⇑ ⇓ arrow keys to set the desired
reset ratio.
11. Press ENTER to accept the change.
The unit is now ready to run. Go back to the
primary menu and start the unit