DEFINITIONS
The following defined terms and symbols are used through- out this manual to bring attention to the presence of hazards of various risk levels, or to bring attention to important infor- mation concerning the life of the product, see Figure 4 below.
FIG. 4
SEQUENCE OF OPERATION
SECTION A: GENERAL OPERATION
POWERING UP THE CONTROL
When the control is powered up, all segments in the LCD are turned on for two seconds. The control displays the control type number in the LCD for two seconds. Next, the software version is displayed for two seconds. Finally, the control enters the normal operating mode.
OPERATION
The control operates up to nine on / off heat sources to con- trol the supply water temperature to a hydronic system. The supply water temperature is based on either the current out- door temperature, an external 0 - 10 V (dc) or 2 - 10 V (dc) signal, or a fixed set point.
Boiler Reset (Stand Alone)
When a boiler demand signal from the heating system is present, the control operates the boiler(s) to maintain a sup- ply temperature based on the outdoor air temperature and Characterized Heating Curve settings, see Figure 5.
Domestic Hot Water
When a DHW demand signal from a DHW aquastat is pres- ent, the control operates the boiler(s) to maintain the supply water temperature at least as hot as the DHW XCHG set- ting. Refer to section E.
Set Point
When a set point demand signal from a set point system is present, the control operates the boiler(s) to maintain the supply water temperature at least as hot as the SETP set- ting. Refer to section F.
External Input 0 - 10 V (dc) or 2 - 10 V (dc)
When an external input signal is present, the control con- verts the signal to a target supply temperature. The control operates the boiler(s) to maintain the required supply water temperature.
FIG. 5
SETBACK (UNOCCUPIED)
To provide greater energy savings, the control has a set- back feature (FIG. 6). With setback, the supply water tem- perature in the system is reduced when the building is unoc- cupied. By reducing the supply water temperature, the air temperature in the space may be reduced even when ther- mostat(s) are not turned down. Any time the UnO Sw (5) and the Com - (1) are connected, the control operates in the UnOccupied mode. When in the UnOccupied mode, the UNOCC segment is displayed in the LCD. The control adjusts the supply water temperature based on the UNOCC settings made in the control. This feature has no effect when the control is used in the External Input mode.
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