A large easy to read display provides current system temperatures and operating status (FIG. 1). The control has outputs for a primary pump and a combustion air damper or alarm. Based on the mode of operation selected, the control can operate different combinations of boiler stages and boiler pumps. ADDITIONAL FUNCTIONS INCLUDE: • Installer and Advanced Access Levels • Primary Pump Output • Individual Boiler Pump Outputs (in applicable modes) • Pump Exercising • Pump Purging (primary and b

This is typical of many commercial cast iron and steel tube boilers. The HI MASS setting stages on additional boilers at the slowest rate. Differential An on / off heat source must be operated with a differential to prevent short cycling. With the control, either a fixed or an auto differential may be selected. The boiler differential is divided around the boiler target temperature. The first stage contact closes when the supply water temperature is % of the differential setting below the boil

An external signal is generated by applying a voltage between 0 v (dc) and 10 v (dc) across the out + and Com - terminals (4 and 1) (FIG. 25). Once voltage is applied, the External Input Signal pointer is displayed in the LCD and the control closes the primary pump contact. The control calculates a boiler target supply temperature based on the external input signal and the settings made in the control. The control then fires the boiler(s), if required, to maintain the target supply temperature.

This item is available in all modes. -67 to 149°F (-55 to 65°C) BOB. sup j Lj g* occ • Boiler Supply - Current boiler supply water temperature as measured by the boiler supply sensor. This item is available in all modes. 14 to 266°F (-10 to 130°C) BOB. ir r T TAflQ 1 J J OCC D1 E1 F1 • Boiler Target - Boiler target temperature is the temperature the control is currently trying to maintain at the boiler supply sensor +/-1/2 of the differential. This item is available in all modes. —, 14