Lochinvar INS7141, MP2, INS7162, TST2313 Section D Boiler Reset Operation, Boiler Pump Purge, Fig

FIG. 12

FIG. 13

BOILER PUMP OPERATION

In certain modes of operation, the control can operate the individual boiler pumps on each boiler in addition to the pri- mary pump. The boiler pump turns on prior to the boiler fir- ing and continues to run after the boiler is turned off. The amount of time that the boiler pump turns on prior to the boiler firing is determined by the BOIL MASS setting. If a BOIL MASS of Lo is selected, the boiler pump turns on 15 seconds prior to the boiler. If a BOIL MASS of Medium is selected, the boiler pump turns on 22 seconds prior to the boiler. If a BOIL MASS of Hi is selected, the boiler pump turns on 30 seconds prior to the boiler. However, if the con- trol is operating based on a set point demand, the boiler pump turns on 5 seconds prior to the boiler, see Figure 13.

Boiler Pump Purge

FIG. 14

The amount of time that the boiler pump continues to run after the boiler turns off is adjustable using the boiler pump purge setting (PURG Boil Pmp).

SECTION D: BOILER RESET OPERATION

SECTION D1: BOILER RESET (STAND ALONE)

BOILER DEMAND

When operating in the stand-alone mode, a boiler demand is required in order for the control to provide heat to the heating system. A boiler demand is generated by applying a voltage between 24 and 230 V (ac) across the Boiler Demand and Common Demand terminals (6 and 7) (FIG. 14). Once voltage is applied, the Boiler Demand pointer is displayed in the LCD. If the control is not in WWSD, the control closes the primary pump contact. The control calculates a boiler target supply temperature based on the outdoor air temperature and the characterized heat- ing curve settings.

9

BOILER TARGET TEMPERATURE

The boiler target temperature is determined from the char- acterized heating curve settings and the outdoor air tem- perature. The control displays the temperature that it is cur- rently trying to maintain as the boiler supply temperature. If the control does not presently have a requirement for heat, it does not show a boiler target temperature. Instead, "- - -" is displayed in the LCD.

CHARACTERIZED HEATING CURVE

The control varies the supply water temperature based on the outdoor air temperature. The control takes into account the type of terminal unit that the system is using. Since dif- ferent types of terminal units transfer heat to a space using different proportions of radiation, natural convection and forced convection, the supply water temperature must be controlled differently. Once a terminal unit is selected, the control varies the supply water temperature according to the