Bosch Buderus SSB399 - Page 10

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Bosch Buderus SSB255 | SSB399 | SSB512 Boilers Control Operations Guide
03.2018 | Bosch Thermotechnology Corp.
Data subject to change
Central Heating Mode 4
(Analog 0-10 Vdc Setpoint Control)
CH Mode“4” - Boiler demand is generated by a 0-10 Vdc analog signal from a
Building Management System (BMS). An initial heat request is generated via a
signal of 1.5 VDC or greater. Boiler modulation between “Design Supply Min”
(par.#23) and “Design Supply Max” (par.#24) will occur between 2 and 10 Vdc.
When a demand voltage of 1.5 VDC or greater is applied the Boiler and CH pump
contacts are energized and the Boiler will target a system supply water temperature
corresponding to the appropriate setpoint temperature based upon the voltage signal
and the minimum and maximum setpoint settings. If the Boiler Supply Temperature
sensor (System Supply Temperature sensor for cascade) exceeds the targeted
setpoint plus “CH Hysteresis” (par.#7) the burner will shut off until the sensor reads
“CH Hysteresis” below the targeted Setpoint Temperature. Once the initial demand
has occurred The Boiler and CH pump contacts will remain energized as long as the
voltage from the BMS remains greater than 1 VDC.
Figure 1
OFF
1.0
1.5
2.0
ON
9
Modulation
CH Setpoint Max
CH Setpoint Min
Voltage (Vdc)
Set Point F°
Central Heating
(CH) Mode
Description
Set these Parameters
Parameter # Description Default Range
CH Mode = “4”
Analog 0-10 VDC
Setpoint Control
4 System pump overrun 300 sec. 0 – 900 sec.
5 Boiler pump overrun 300 sec. 0 – 900 sec.
7 CH Hysteresis 5.4°F 0 - 36°F
9 Anti-cycle period 180 sec. 10 – 900 sec.
10 Anti-cycle Temp Diff 12.6°F 0 - 36°F
23 Design Supply Min 68°F 39.2 – 179.6°F
24 Design Supply Max. 194°F 80.6 - 194°F
Table 6