Worcester 7735600658 Installation And Maintenance Instructions Manual Download Page 5

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Product Information

Greenstar – 6721852556 (2022/11)

System separation

• The two heat exchangers for DHW and heating hydraulically

disconnect the primary heating circuit from the heating circuit.

DHW mode

• Opening the water tap activates the flow turbine [31]. The minimum

volumetric flow rate is 2 l/min.

• The DHW control valve [1] modulates the heating water on the

primary side to achieve the preset DHW temperature.

• The control valve for the heating remains closed [3] (DHW priority

function).

• Primary side heating water flows through the plate heat exchanger

[32] and heats the potable water instantaneously.

• If there is a risk of scalding, the thermal overload protection [25]

interrupts the flow. The valve opens automatically following a cool
down time.

Heating mode

• The control valve for the DHW [1] remains closed until DHW is

requested (DHW priority function).

• The heating control valve [3] modulates according to the required

heating capacity. The flow temperature remains the same and
corresponds to the flow temperature of the primary circuit.

Summer bypass function

• This function bypasses the longer heating-up period of the pipework

in the primary circuit which occurs when the heat interface unit has
been inactive for a longer period. This reduces the DHW heating
waiting times. The heat exchanger is not kept warm continuously. The
summer bypass function can be activated in two ways.

• Variant 1 (standard) - electronic keep hot without thermal bypass,

using the default electronic bypass. The DHW control valve [1] is
used to allow water to run through HIU. The trigger temperature for
this function is fixed at 41°C and can only be changed by a Sense II
room controller (accessory). With this version, the quantity of heat is
recorded by the heat meter (option) [10].

• Variant 2 (accessory) - using the thermal bypass option [12]: the

heating water in the primary circuit flows through the bypass valve.
This ensures that the temperature of the hot water at the heat
interface unit is 30-70 °C. In this case the quantity of heat is

not

recorded by the heat meter (accessory) [12]!

If the bypass valve is installed, the electronic bypass function must

not

be selected in the room controller and the jumper must be removed
(



Fig. 53, page 29 [19]).

The BESA requirements are only achieved with the electronic bypass -
not with the thermal bypass (accessory).

Frost protection

• System frost protection: as soon as the temperature sensor [10]

sends a frost protection signal, the heating pump is activated.

• Device frost protection: as soon as the temperature at the flow

temperature sensor [24] for the heating is below 5 °C, the control
valve opens the heating.

Limiting the return temperature in the heating circuit

• If the system is designed correctly, it is not necessary to limit the

return temperature [8].

• The return temperature limit is set to 50 °C at the factory.
• This temperature can only be changed with the room controller Sense

II.

• When the room controller is removed, the set value is saved.

2.3

Type Plate

The data plate includes the performance information, approval data and
serial number of the product [2]. There is an additional data plate behind
the control unit [1].

Fig. 4

Type plate and data plate

2.4

Appliance type overview and accessories

Example appliance: HIU KE

• HIU = heat interface unit
• E = differential pressure control valve (DPCV)
• K = higher DHW output

Table 2 Appliance type overview

Refer to the Technical product brochure for a complete overview of all
available accessories. Information on assembly is enclosed with the
accessories.

Table 3 Accessory part

2.5

Product dimensions and minimum clearances

The protection class of the station is IPX4D.

Typ

Typ-Nr.

Accessory NOT possible

HIU

7735600658

Heat meter wired Mbus

HIU

1) with heat meter wired Mbus (standard)