Bosch Buderus SSB512 - Heating Modes; Central heating (CH) mode

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Bosch Buderus SSB255 | SSB399 | SSB512 Boilers Control Operations Guide
03.2018 | Bosch Thermotechnology Corp.
Data subject to change
3 Heating Modes
3.1 Central heating (CH) mode
There are 6 onboard CH Mode settings which may be selected with the SSB Boiler.
1. CH Mode = “0” [default mode] Setpoint control of the boiler using dry
contacts (TT)
2. CH Mode = “1” Outdoor Reset using ON/OFF control of the boiler using dry
contacts (TT)
3. CH Mode = “2” Full Outdoor reset with no heat demand
4. CH Mode = “3” Permanent Setpoint Demand
5. CH Mode = “4” Analog control (0-10Vdc) of set point temperature
6. CH Mode = “5” Analog control (0-10Vdc) of Boiler Power (%)
Central Heating Mode 0 [default mode]
(Setpoint control of the boiler using dry contacts #11 and #12)
CH Mode “0” - Boiler demand is generated thru a call for heat on low voltage contacts
#11 and #12 (dry contacts only). The Boiler will then target a temperature equal to
“CH Setpoint” (par.#3) at the Supply Temperature Sensor. If Temperature exceeds
the target Setpoint temperature by “CH Hysteresis” (par.#7) the burner will shut off
until the Supply Temperature Sensor drops the value of “CH Hysteresis” below the
target Setpoint Temperature.
Example:
If “CH Setpoint” is set for 140°F and CH Hysteresis is set for 10°F and there is a call
for heat on #11 and #12 the burner will start when the Boiler Supply Temperature
(System Supply Temperature sensor for cascade) reads a temperture of 130°F or less
and will remain operating until the call for heat is satisifi ed or until the sensor reads
a temperature of 150°F or greater. As long as the call for heat remains the Boiler and
CH Pump contacts will remain energized. The Burner will remain off until temperature
falls to 130°F.
Central Heating
(CH) Mode
Description
Set these Parameters
Parameter # Description Default Range
CH Mode = “0”
Setpoint control using dry
contacts (TT)
3 CH Setpoint 176°F 68 - 194°F
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 2