Bosch SSB1000 TL - Heat Exchanger Differential Protection

SSB 6720892984 (2019/02) US
Main control | 37
Relay output
For the relay output the following output options are available:
Output option
0 ¨ Disabled
1 ¨ General pump
2 ¨ CH pump
3 ¨ DHW pump
4 ¨ System pump
5 ¨ Cascade pump
6 ¨ Alarm relay
7 ¨ Filling valve
8 ¨ LPG tank
9 ¨ External igniter
10 ¨ Air-damper
14 ¨ Zone pump
15 ¨ Mixing valve open
16 ¨ Mixing valve close
Triac output
For the triac output the following output options are available:
Output option
0 ¨ Disabled
1 ¨ General pump
10 ¨ Air-damper
11 ¨ HSI
12 ¨ Mod.Pump
3-Way valve output
The 3-way valve output can be selected for CH pump/valve or DHW
pump/valve. When selected for CH, the output is powered when there is a
CH demand. When selected for DHW, the output is powered when there
is a DHW demand.
5.3.11 Heat exchanger protection: max differential (Rev 3.0.0.0)
To avoid temperature differences that are too large in the primary heat
exchanger, the burner load automatically decreases when the Return-
Supply temperature differential increases too much.
At maximum burner power the ΔT
Hx_Diff_DeltaT_Min is limited
to 40°C (72°F) and at low burner power a ΔT above 48°C (86°F) (=
Hx_Diff_DeltaT_Min +8°C) is allowed.
Above ΔT 52°C(94°F) (=
Hx_Diff_DeltaT_Min +8°C + 5°C) the
burner is switched OFF during
Diff_Max_Wait_Time (settable).
In between 40°C (72°F) and 48°C (86°F) ΔT over the heat exchanger,
the burner power is linear limited.
To achieve this the PID output value is linear limited between minimum
(@48°C ΔT) and maximum (@40°C ΔT).
However when the calculated PID output for temperature control is
already below this limit, this output value remains the current control
value.
Relevant variables
Specic Parameters Level
(Default) Value Settable
°C °F °C °F
HX Diff DeltaT Min
[°C/°F]
3: Factory 40 72 10...80 18...144
HX Diff Max Wait
Time
[sec.]
3: Factory 0 1...255 sec.
5.3.12 Appliance selection (Rev 3.0.0.0)
The control is designed to store specic parameter sets of different boiler
models.
By dening specic setting for different appliance models the same
control can be used for a complete product range. Depending on which
model the control is applied to, it only will be necessary to change just
one single parameter.
When this parameter is changed the following settings are changed:
• Maximal fan speed
• Minimal fan speed
• Ignition speed(*)
• Maximum ue gas temperature
(*) Ignition speed is the same as Pre Purge Speed and Post Purge
speed.
The appliance can store 6 appliance type settings.
The following appliances are available (example):
ID
Min. fan speed
(rpm)
Ignition fan
speed (rpm)
Max fan speed
(rpm)
Max ue gas
temp.
50 1500 3750 6000 95°C / 203°F
51 1500 3750 6000 95°C / 203°F
52 1500 3750 6000 95°C / 203°F
53 1500 3750 6000 95°C / 203°F
54 1500 3750 6000 95°C / 203°F
55 1500 3750 6000 95°C / 203°F
Relevant variables
Specic Parameters Level (Default) Value Settable
Appliance type
[-]
Selection for the appliance
type
2: Installer 50 50...55
5.3.13 Anti-legionella protection (Rev 3.0.0.0)
Anti-Legionella protection is enabled for DHW modes with an external
tank with a sensor (DHW Mode 1).
To prevent legionella a special function is implemented in the software.
• When DHW Mode 1 is selected the Anti-Legionella protection will be
checked on the
T_DHW_Out sensor.
This sensor will be named the
Anti_Legionella_Sensor in the
remaining part of the explanation.
At least once every 168 hours (7 days) the
Anti_Legionella_Sensor
must reach a temperature above
Anti_Legionella_Setpoint for a
time specied by
Anti_Legionella_Burn_Time .
If 7 days have passed and these conditions are not met, the burner is
forced to heat-up the system for Anti-Legionella.
When the
Anti_Legionella_Sensor temperature is below Anti_