Separation - Bosch UT-L 1 Technical Manual

64 | System examples
9.11 2-boiler system with UNIMAT UT-L boiler without flue gas heat exchanger and UT-L boiler with
condensing heat exchanger: boiler circuit control unit with hydraulic separation
SR
PK
FZ
FK
VK RK
CFB 910
Fig. 45 System example of a 2-boiler system with UNIMAT UT-L boiler with and without condensing heat exchanger; boiler
circuit control unit with hydraulic separation (list of abbreviations
The circuit diagram is only a schematic
illustration! Information regarding all
system examples  page 47 ff.
AREA OF APPLICATION
• UNIMAT UT-L boiler with condensing heat exchanger
and UNIMAT UT-L boiler
• CFB boiler circuit control unit
– Maintaining the operating conditions
– Enabling of burner stages
• Hydraulic separation
Brief description of the system
• The UT-L with condensing heat exchanger is the lead
boiler
• 2-stage or modulating burner mode
• Boiler sequence can be reversed, but is not
recommended
• Hydraulic shut-off of the lag boiler with time delay
• Automatic or weather-compensated load limitation.
6 720 807 794 (2013/04)
THV
FV1
PH1
SH1
FVS
WH
SR
PK
FZ
FK
RK VK
VWT
CFB 930
+ CMC 930
RWT
KR

page 47)
Function description
The 3-way valve is actuated to control the return
temperature. The return temperature sensor measures
the boiler return temperature. If this falls below the set
value, the flow rate to the heating return is constantly
restricted by actuating the 3-way valve. If the return
temperature rises above the set value, the 3-way valve is
reopened and the flow rate to the heating circuit
increases.
Any boilers not in operation are hydraulically shut off.
Targeted utilisation of the condensing effect is possible
with the condensing heat exchanger (ECO 6) connected
separately to the low temperature heating circuit.
Special design information
• The boiler circuit pump run-on times are set to 30-
60 minutes for the lead boiler and five minutes for the
lag boiler.
• We recommend distributing the total rated output
between the boilers so each has 50 % (maximum 60/
40 %).
• The ECO 6 pump should be actuated in parallel to the
burner. Match the head to the pressure loss of the
ECO 6 and the connection pipework.
• If there are shut-off valves between the boiler and
ECO 6, an additional safety valve and pressure gauge
are required at the ECO 6.
• Protect the ECO 6 with an on-site safety temperature
limiter or high limit safety cut-out.
• This scheme can also be used if a third boiler is
connected.
HK1 HK2
HT NT
THV
FV2
PH2
SH2
PWT
6 720 803 977-25.1itl
UNIMAT
VV
VR