1-Boiler System With Unimat Ut-L Boiler With Flue Gas Heat Exchanger: Boiler Circuit Control Unit - Bosch UT-L 1 Technical Manual

62 | System examples
9.9

1-boiler system with UNIMAT UT-L boiler with flue gas heat exchanger: boiler circuit control unit

Fig. 43 System example with boiler circuit control unit (list of abbreviations
1)
[ ] Enabling (potential-free)
 Burner stage I
 Burner stage II or modulation
The circuit diagram is only a schematic
illustration! Information regarding all
system examples  page 47 ff.
AREA OF APPLICATION
• UNIMAT UT-L boiler with flue gas heat exchanger or
condensing heat exchanger
• CFB boiler circuit control unit
– Maintaining the operating conditions
– Enabling of burner stages
• Partial flow of the condensing heat exchanger
(ECO 6)
Brief description of the system
• Minimum return temperature controlled via a
separate actuator in the boiler circuit and a boiler
circuit pump
• 2-stage or modulating burner mode
• Control of heating circuit using CFB control unit or on-
site control unit
6 720 807 794 (2013/04)
SR
KR PK
FZ
RK VK
VWT
CFB 810
+ CME 930
RWT
HK1
HT
THV
THV
FV1 FV2
PH1 PH2
SH1 SH2

page 47)
Function description
To control the return temperature, the 3-way valve is
actuated, as is the boiler circuit pump which is installed
in the bypass line to the boiler. If the return temperature
at the return temperature sensor falls below the set
value, the flow rate to the boiler return is constantly
restricted and the bypass from the heating return to the
heating flow is opened.
The heating circuit flow rate remains almost constant
even during this operating phase. The boiler circuit
pump safeguards the optimum flow rate in the boiler
circuit. Targeted utilisation of the condensing effect is
possible with the ECO 6 connected separately to the low
temperature heating circuit.
Special design information
• If a check valve is installed, the boiler circuit pump
run-on time should be five minutes. If no check valve
is installed, set a run-on time of 60 minutes.
• The ECO 6 pump must 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.
HK2
NT
VV
VR
PWT
KR
6 720 803 977-23.1itl
UNIMAT