Product Details; Important Usage Information; Function Description; Basic Principle - Bosch EMS 2 Manual De Instalación

12 | Product details

Electrical work
Electrical work must only be carried out by qualified and competent
persons.
▶ Before carrying out electrical work:
– Isolate all poles of the mains voltage and secure against
unintentional reconnection.
– Using suitable means, test that the power supply is isolated.
▶ 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 regular 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 are used to obtain greater
heat output. See example wiring diagram on page 90.
• The module is used to activate the heat source (e.g. boiler).
• The module is used to record external, flow and return temperature.
• Configuration of the cascade system with a user interface (e.g.
heating control) with an EMS 2/EMS plus BUS interface (not possible
with all user interfaces).
The combination options for the modules are shown in the connection
diagrams.
2.1

Important usage information

The module communicates via an EMS 2 / EMS plus interface with other
EMS 2 / EMS plus-enabled BUS modules (e.g. MM100).
If the pump speed is too low when the burner is started in
heat sources with a variable speed pump, high
temperatures and frequent burner cycles can arise.
▶ If possible, configure the pump to On/Off mode with
100 % output, otherwise set minimum pump output to
the highest possible value.
• The module can be connected to user interfaces with an EMS 2 / EMS
plus (Energy Management System) BUS interface. Alternatively, an
external output demand or temperature demand can be connected
via the 0-10 V interface on the module.
• The module only communicates with heat sources with EMS, EMS 2,
EMS plus and 2-wire BUS (HTIII) (with the exception of heat sources
of product series GB112,GB132, GB135, GB142, GB152).
• Only connect heat sources from a single manufacturer.
6 720 819 669 (2016/05)
• Only use with cascade installations containing natural gas, LPG or oil-
fired heat sources (heat pumps with an EMS 2 / EMS plus BUS
interface are not allowed).
• The installation location must be suitable for the IP rating stated in
the module specifications.
• If a DHW cylinder is connected directly to a heat source:
– The system controller or 0-10 V controller does not display any
information about the DHW system and does not influence the
DHW heating.
– With direct DHW heating, a cylinder smaller than 400 litres is
recommended.
– The domestic hot water including thermal disinfection is
controlled directly by the heat source.
– Thermal disinfection may have to be monitored manually.
Observe the heat source instructions.
– If it is not possible to monitor thermal disinfection at the device,
do not connect a DHW cylinder directly to a heat source.
2.2

Function description

2.2.1

Basic principle

The module modulates the overall output of the cascade depending on
the temperature difference between the flow temperature (at the
hydraulic separator, i.e. low loss header or plate heat exchanger) and
the system set temperature. With it, the devices are switched on or off
one after the other. The devices are always modulated via the
performance specification to attain the set target temperature. Before a
device is switched off, the module activates the heating pump for
2 minutes to bring the device up to operating temperature.
In order to smooth out the changes in cascade output the MC 400
module modulates the first heat source to achieve maximum output.
When an additional heat source is fired, the first heat source
simultaneously modulates down. This avoids large jumps in the overall
cascade output. To maximise the overall cascade output, the first heat
source then modulates upwards, whilst the second heat source remains
at minimum modulation. The second heat source will then modulate
upwards depending on the required heat demand. This logic continues
for each additional heat source.
The above control logic is reversed when the overall cascade output
modulates down from its maximum output. The output of the heat
sources therefore overlap to avoid sudden jumps in output. If the
operating temperature is too high, this will continue until all heat sources
are switched off. When the heat requirement ends, all heat sources stop
firing simultaneously.
2.2.2

Time limits

If more performance is required than a heat source can provide or the
temperature falls below the set temperature
source is only after a defined time
After the start of another heat source, the module waits 1½ minutes,
until a further performance increase takes effect. This prevents
overshooting of the temperature as far as possible.
This basic principle applies to the functions with coding card setting 1 to
4 and 8 to 9. With these functions, the module always controls the set
temperature in the system, and the tolerated lower/upper temperature
and serves as a switching differential for the heat source.
1) Tolerated lower temperature, setting range 0-10 K, default 5 K (not used for
performance control)
2) Starting delay of the sequential device, setting 0-15 minutes, factory setting
6 minutes, see section 4.5 for more information
1)
the next available heat
2)
switched off from the module.
MC 400