System examples | 53
6 720 807 794 (2013/04)UNIMAT
9.2.3 Safety equipment for the flue gas heat
exchanger
The flue gas heat exchanger requires an additional safety
valve with pressure gauge and venting facility if a shut-
off device is installed between the boiler and flue gas
heat exchanger. If the heat exchanger is connected to
the boiler without a shut-off device, there is no need for
additional safety equipment.
9.2.4 Maximum operating flow temperatures
In combination with the various boiler controls, the
boilers can reach different, maximum possible operating
flow temperatures (maximum setting value of the
control unit). When these temperatures are reached, the
burner is shut down by the control unit. The (re)start
temperature is higher by the specific hysteresis. In
general, this results in the maximum achievable average
operating flow temperatures, according to table.
The boiler temperature must be at least 70 °C. It can be
modulating or kept constant.
9.3 Sizing and installation information
9.3.1 Boiler circuit pump in the bypass as shunt pump
Fig. 35 Sample hydraulic circuit for a 1-boiler system with boiler circuit pump in the bypass
FR Return temperature sensor
KR Flow-check valve
PK Boiler circuit pump
RK Boiler return
SR Actuator, return temperature raising facility
SV Safety valve
VK Boiler flow
VSL Safety valve connector
Control unit
Maximum setting
value of the control
unit
Maximum
achievable flow
temperature at high
limit safety cut-out
110 °C
[°C] [°C]
CFB 810 105 / 95 92
CFB 910 / 930
1)
1) Applies only for boiler circuit control unit. Heating circuits can
only be operated up to a maximum of 90 °C
105 / 95 92
UNIMAT B.C & D 110 / 100 100
Table 28 Achievable temperatures subject to control unit
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