Product Details; Important Notices On Usage; Function Description/Control Strategies; Serial Standard Cascade - Bosch MC 400 Installationsanleitung

12 | Product details

▶ The product requires different voltages.
Do not connect the extra-low voltage side to the mains voltage or vice
versa.
▶ Also observe connection diagrams of other system components.
Handover to the end user
When handing over the heating system, explain the operating conditions
to the end user.
▶ Explain how to operate the heating system, with particular emphasis
on all safety-related actions.
▶ Explain that conversions or maintenance must only be carried out by
a suitably qualified engineer.
▶ Highlight the need for inspections and maintenance for safe and
environmentally friendly operation.
▶ The installation and operating instructions must be given to the end
user for safekeeping.
Damage caused by frost
The system can freeze if it is switched off:
▶ Observe the notices regarding frost protection.
▶ Due to the additional functions, e.g. DHW heating or anti-seizing
protection, the system should always be left on.
▶ Correct any faults immediately.
2 Product details
The module is designed to control cascade systems. A cascade system is
a heating system in which several heat sources (i.e. boilers) are used to
achieve greater heat output, see example wiring diagram on page 86.
• The module is used to activate the heat source.
• The module is used to record outdoor, flow and return temperatures.
• Configuration of the cascade system can be completed with an EMS
user interface.
The combination options for the modules are shown in the connection
diagrams.
2.1

Important notices on usage

The module communicates via an EMS interface and EMS enabled
boilers, such as various Greenstar boilers.
• The module can be connected to user interfaces with the (Energy
Management System) BUS interface. Alternatively, an external
performance or temperature requirement can be connected via the
0-10 V interface to the module.
• Only connect heat sources from a single manufacturer in the system.
• Only use heat sources in a system with natural gas, LPG or oil as the
energy source.
• The installation location must be suitable for the IP rating stated in
the module specification.
• If a DHW cylinder is connected directly to a heat source:
– The system controller or 0-10 V controller does not display
information on the hot water system and does not influence the
DHW heating.
– The domestic hot water including thermal disinfection is
controlled directly by the heat source.
– With direct DHW heating, it is recommended to use a cylinder
smaller than 400 L.
– If it is not possible to monitor the thermal disinfection of the
device, do not directly connect a DHW cylinder to a heat source.
6 720 809 453 (2014/12)
2.2

Function description/control strategies

2.2.1

Serial standard cascade

The connected heat sources/modules are turned on and off according to
the wiring.
For example, the heat source is connected to the BUS1 terminal as the
first terminal, the heat source is connected to the BUS2 terminal as the
second terminal, etc.
If the heat source is turned off, the sequence is reversed. The heat
source which was connected last is turned off first.
The controls take into account sudden changes in heat demand.
2.2.2

Serial optimised cascade

The aim of this control strategy is to operate the heat sources to balance
burner run times.
The connected heat sources are turned on and off according to the
burner runtime. The burner runtimes are compared every 24 hours, and
the sequence is re-established.
The heat source with the shortest burner runtime is connected first, and
the one with the longest runtime is connected last, balancing wear and
tear.
If the heat source is turned off, the sequence is reversed. The heat
source which was connected last is turned off first.
The controls take into account sudden changes in heat demand.
2.2.3

Serial cascade with peak load coverage

This control strategy is recommendable when the heat energy demand is
even over a long period (base-load output) with brief peaks (peak load).
The heat sources connected to terminals BUS1 and BUS2 satisfy the
base-load output. The heat sources at terminals BUS3 and BUS4 are
connected to cover and the energy demand in peak loads.
The heat sources at terminals BUS3 and BUS4 are connected when the
required flow temperature rises above an adjustable limit, or the outside
temperature falls below an adjustable limit.
If the heat source is turned off, the sequence is reversed. The heat
source which was connected last is turned off first.
The controls take into account that the performance increases or
decreases suddenly when a heat source is connected or disconnected.
2.2.4

Parallel cascade

This control strategy should be used when the heat sources have a
similar degree of modulation.
The heat sources are operated to match burner runtimes as closely as
possible. Generally, all heat sources will be in operation. When all heat
sources are running at minimum performance, they will modulate
accordingly.
MC 400