Setting Control Unit Parameters; Settings With Third Party Control Units - Bosch Uni Condens 8000 F Installation And Maintenance Instructions Manual

Control unit
Control unit settings
▶ Select temperatures ( tab. 14, page 31) at high limit safety cut-out
and in the control unit.
The maximum temperature demand is not a value that is set directly. The
maximum temperature demand is composed of the set temperature and
the rise.
Example DHW demand:
Sum of the set DHW temperature (60 °C) and the parameter "boiler
temperature increase" (20 °C) in the "DHW" menu:
60 °C + 20 °C = maximum temperature demand 80 °C.
Example heating circuits:
Sum of the set temperature of the heating circuit with mixer with the
highest temperature required (70 °C) and the parameter "boiler
temperature increase" (5 °C) in the "Heating circuit data" menu:
70 °C + 5 °C = maximum temperature demand 75 °C.
All maximum temperature demands must always be 7 K below the
maximum selected boiler water temperature.
7.3.4

Setting control unit parameters

The controller settings listed in tab. 15, page 32 apply for the control
unitsCC 8311and CC 8312.
To ensure that the control unit operates correctly if burner type "dual fuel
burner" is selected, connect a volt-free contact to terminal "ES" to
change the fuel type.
Burner
Burner type for fuel
Burner Gas
Single fuel burner Modulating
2-stage
Dual-fuel burner Modulating
Dual-fuel burner Modulating
Table 15 Controller settings for CC 8311 and CC 8312 control units
7.4

Settings with third party control units

NOTICE:
System damage due to incorrect sensor position!
The sensors of the high limit safety cut-out (STB) and the temperature
controller (TR) must be fitted at the installation location on the top of the
boiler ( fig. 23, page 24).
▶ In the case of third party control units, match the sensor immersion
sleeve to the diameter of the sensors used.
▶ Do not change the length of the immersion sleeve.
32
Control unit setting
Burner type
to be selected
Oil
Modulating
2-stage
Modulating 2-stage
2-stage 2-stage
Modulating Dual-fuel burner
2-stage Dual-fuel burner
Observe the operating conditions in chapter 2.9, page 9 and observe
chapter 6.14, page 24 when installing sensors.
• The third party control unit (building management system or PLC
controllers) must ensure a sufficient difference between the
maximum internal boiler water temperature and the high limit safety
cut-out.
The purpose of optimum control unit settings is to achieve long burner
runtimes and avoid rapid temperature changes in the boiler. Gentle
temperature changes result in a longer service life of the heating system.
The control strategy of the control unit must therefore be prevented from
becoming ineffective, i.e. through the boiler temperature controller
switching the burner on and off.
Observe the following points when selecting the control unit.
• The control unit must ensure that the maximum internal boiler
temperature and the high limit safety cut-out are at least 5 K apart.
• It must also be ensured that the control electronics rather than the
boiler temperature controller switch the burner on and off.
• The control unit must ensure that the burner is switched to low load
before a controlled shutdown. If this is not observed, the safety shut-
off valve (SAV) in the gas train may lock out.
• Select and adjust the control unit so as to allow a gentle start-up of
the boiler with a time delay when the system is cold. The heat energy
demand must only be switched on with time delay.
• After the burner demand, an automatic timer (for example) should
limit the burner to low load for a period of approx. 150 seconds. A
restricted heat demand will prevent uncontrolled starting and
stopping of the burner.
• It must be possible to show the number of burner starts at the control
unit used (or alternatively at the burner control unit).
• The maximum number of burner starts must be monitored. There
should be a maximum of 6 burner starts per hour (averaged over
burner runtime on one day). If the number of starts is higher, the user
should be notified. The system must be checked to find out whether
the number of burner starts can be reduced. The customer service of
the manufacturer can provide assistance with optimisation of the
system.
Unit
Time constant on s
temperature
controller, max.
Time constant on s
temperature switch/
limiter, max.
Minimum difference K
between burner on
and off temperatures
Table 16 Operation conditions
Uni Condens 8000 F – 6720867056 (2016/10)
Value
40
40
7