Functional Principle; Intended Use; Minimum Volume And Execution Of The Heating System; Preparatory Pipework Connections - Bosch Compress 3000 AWES 2-6 Installation Manual

4.3

Functional principle

The function is based on the demand-actuated control of the compressor
output by switching in the integrated auxiliary heater via the indoor unit.
The control unit controls the outdoor unit depending on the set heating
curve.
If the outdoor unit is unable to satisfy the house's heat energy demand,
the indoor unit automatically starts the auxiliary heater which produces
the desired temperature in the house together with the outdoor unit.
The DHW heating is controlled via the TW1 sensor in the DHW cylinder.
During the heat-up phase of the DHW cylinder, the heating mode of the
heating system is temporarily switched off via a 3-way valve (accessory).
Once the DHW cylinder is heated up, heating mode is continued by the
outdoor unit.
Heating and DHW mode when the outdoor unit is deactivated
When the outdoor temperature is less than –20 °C (adjustable), the
outdoor unit is automatically turned off and is unable to produce any
heat. In this case, the auxiliary heater of the indoor unit adopts the
heating and DHW mode.
4.4

Intended use

The wall mounted indoor unit must only be installed in sealed heating
systems according to EN 12828.
Any other use is considered improper use. Any damage that results from
such use is excluded from liability.
4.5 Minimum volume and execution of the heating
system
Ensure the minimum flow rate according to the specifications in the
chapter 11.1.
To safeguard the heat pump function and avoid an excessive number of
start/stop cycles, incomplete defrosting and unnecessary alarms, it
must be possible to store a sufficient amount of energy in the system.
This energy is stored in the water volume of the heating system, and also
in the components of the system (radiators) and concrete floor
(underfloor heating system).
As the requirements for different heat pump installations and heating
systems vary considerably, a minimum water volume in litres is generally
not specified. Instead, the system volume is considered to be sufficient
if certain conditions are met.
Only an underfloor heating circuit without buffer cylinders, no
mixer:
For the heat pump and defrosting function to work, at least 22 m
heatable floor area must be available. Furthermore, a temperature
controller must be installed in the largest room (reference room). The
room temperature measured by the temperature controller is used to
calculate the flow temperature (principle: weather-compensated control
with room temperature hook-up). All zone valves of the reference room
must be completely open. In certain situations, the electric booster
heater can be activated to ensure complete defrosting. That depends on
the available floor space.
Only the radiator circuit without a buffer cylinder or mixer
For the heat pumps and defrosting function to work properly, there must
be at least 4 radiators with an output of at least 500 W. Make sure that
the thermostatic valves of these radiators are fully opened. If this
condition can be met within a living area, a temperature controller is
recommended for this reference room so that the measured room
temperature can be used to calculate the flow temperature. In certain
Compress 3000 AWES – 6720892204 (2020/06)
situations, the electric booster heater can be activated to ensure
complete defrosting. This depends on the available radiator surface
area.
Heating system with 1 heating circuit without mixer and 1 heating
circuit with mixer without a buffer cylinder
For the heat pumps and defrosting function to work properly, the heating
circuit without mixer must have at least four radiators with an output of
at least 500 W. Make sure that the thermostatic valves of these radiators
are fully opened. In certain situations, the electric booster heater can be
activated to ensure complete defrosting. This depends on the available
radiator surface area.
Special feature
If both heating circuits have different operating times, each heating
circuit must be able to ensure the operation of the heat pump
independently. Make sure that at least 4 radiator valves of the heating
circuit without mixer are completely open and that a floor surface area of
2
at least 22 m is available for the (underfloor) heating circuit with mixer.
In this case, temperature controllers are recommended for the reference
rooms of both heating circuits so that the measured room temperature
can be used to calculate the flow temperature. In certain situations, the
electric booster heater can be activated to ensure complete defrosting.
If both heating circuits have identical operating times, the heating circuit
with mixer does not require a minimum area because the 4 radiators with
a constant flow ensure the operation of the heat pumps. A temperature
controller is recommended in the area of the open radiator valves so that
the outdoor unit automatically adjusts the flow temperature.
Only heating circuits with mixer (also applies to heating circuits
with fan convectors)
To ensure that a sufficient amount of energy is available for defrosting, a
buffer cylinder with a minimum capacity of 50L for sizes 2-6 and 100L
for sizes 8-15 is required.
An additional heating circuit pump is a prerequisite for this.
4.6

Preparatory pipework connections

The ball valve with particle filter is installed horizontally in the return of
the heating system. Note the direction of flow of the filter.
The drain pipe of the pressure relief valve in the indoor unit must be
installed protected against frost, and the drain pipe must be run to visibly
terminate in a drain.
4.7

Setting up

▶ Dispose of the packaging according to the instructions on the
2
of
packaging.
▶ Take out the enclosed accessories.
5

Installation

NOTICE:
Residue in the pipework can damage the system.
Residue and particles in the heating system impair the flow rate and lead
to faults.
▶ Before connecting the indoor unit, flush the pipe system to remove
any foreign bodies.
Installation
7