Hoval RoofVent CON-9, Design Handbook

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22 Design for injection system
Instead of a diverting system, an injection system can also
be installed in the load circuit.
Note
The injection system is particularly well suited for
applications where only a low heat output is required
due to high internal heat gains.
Please note the following:
■ In the design for the injection system, the pumps in the
load circuit are also controlled directly by the DigiUnit
terminal box, as well as the mixing valves.
■ Terminals for wiring the mixing valves are located in the
connection box.
■ Terminals for wiring the pumps in the load circuit are
located in the DigiUnit terminal box.
■ Make sure that valves and pumps which meet the
following requirements are provided on-site.
Requirements for mixing valves
■ Use three-way mixing valves with linear characteristics
and high quality.
■ The valve authority must be ≥ 0.3.
■ The maximum run time of the valve actuator is 150 s.
■ The valve actuator must be continuous, i.e. the stroke
changes in proportion to the control voltage (DC 0…10 V).
■ The valve actuator must be designed for emergency
operation with a separate manual control (AC 24 V).
Requirements for pumps
Voltage _______ 3 x 400 V
Output _______ up to 1.8 kW
Current _______ up to 5.0 A
Heating pump
Mixing valve heating
Cooling pump
Mixing valve cooling
Table K28: Electrical connections
Options
Design for injection system