DeLonghi AWR-MTD2-XE Service Manual download pdf (Page 7)

AWR MTD2 XE

AWR_MTD2_XE_0011_0091_201109_EN HFC 410A

FAN SPEED CONTROL

To enable the unit to function correctly at different outside tem-

peratures, a microprocessor with pressure reading via pressure

transducer controls fan rotation speed. This allows the

exchange of heat to be increased and/or decreased, maintain-

ing condensing or evaporation pressures essentially constant.

The fan operates independently of the compressor.

DOMESTIC HOT WATER PRODUCTION

The controller manages domestic hot water production using a

3-way valve installed outside of the unit, deviating the flow of

hot water to the DHW storage tank, which must be suitably

sized according to the type of usage.

Production is enabled when the water temperature inside the

DHW storage tank (probe BT8) is less than the DHW set point.

The production of domestic hot water is guaranteed in both

summer and winter, according to the operating limits shown in

this manual.

If heat pump operation is expected outside of the limits, consid-

er using a supplementary source of heat, managed directly by

the controller.

An electric heater should be installed inside the DHW storage

tank to ensure the temperature does not fall below 10°C in the

event of extended periods of heat pump inactivity (standby).

LEGIONELLA PREVENTION FUNCTION

The Legionella prevention function ensures the elimination of

the Legionella bacteria that reside in domestic water storage

tanks.

The temperature and duration of the Legionella prevention

cycles to eliminate bacteria are typically:

• 2 minutes > 70°C

• 4 minutes > 65°C

• 60 minutes > 60°C

The Legionella prevention cycles are managed directly by the

controller, enabling the heater in the domestic hot water storage

tank domestic, with the possibility to set the duration, tempera-

ture, day and time.

AUXILIARY RESOURCES

System operation can be distinguished as monovalent, all-elec-

tric or bivalent. The controller can activate the external source

to achieve one of the functions listed above.

Monovalent operation

For monovalent operation, the heat pump has to meet the entire

demand of the building.

There may be excessive heating capacity of the heat pump

above all when the outside air temperature is above zero, as

well as high power consumption.

Make sure the home’s energy meter is correctly sized.

Solution suggested for new homes.

All-electric operation

In all-electric operation the heat pump is integrated with an

electric heater to meet the entire demand of the building.

The electric heater is activated below certain outside tempera-

tures so as to satisfy demand in the building that the heat pump

cannot manage on its own.

Considering the reduced number of hours of heat pump opera-

tion at low outside temperatures during the winter period, oper-

ation of the supplementary heater will also be reduced, and

consequently power consumption will be negligible.

Therefore the system’s seasonal energy efficiency remains

unchanged.

This solution is suggested for new homes and lower invest-

ments than monovalent heat pumps.

Bivalent operation

In the case of bivalent operation the heat pump meets the

needs of the building down to a certain outside temperature,

called the bivalence point.

Below the bivalence point the heat pump switches off and only

the auxiliary source (e.g. boiler) provides heat for the building.

This solution is ideal for traditional systems and renovations.

-15 -10 -5 0 5 10 15 20

Pt [kW]

Outside Air Temp. [°C]

Heat pump

Heat Capacity

P.d.C

Winter Load

-15 -10 -5 0 5 10 15 20

Pt [kW]

Outside Air Temp. [°C]

Heat Capacity

P.d .C

Elec. Heater

Heat pump

Winter Load

-15 -10 -5 0 5 10 15 20

Pt [kW]

Outside Air Temp. [°C]

Heat Capacity

P.d .C

Boiler

Heat pump

1 2 3 4 5 6 7 8 9 10 11 12 ... 57 58

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DeLonghi AWR-MTD2-XE Service Manual Page 7

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