26
AWR MTD - AWR MTD/B
GB 01/2009
The defrost cycle is started if the evaporation pressure falls
below the effective start defrost set point, a value that may
change, as represented in the graph, in relation to the out-
side air temperature.
A countdown starts, and only at the end is the cycle
reversed to cooling mode, if the pressure remains below the
effective start defrost set point
If the rises back above the effective start defrost set point,
the defrost timer is set to zero.
The defrost ends when the set pressure value is reached or
alternatively after a maximum time.
3-WAY VALVE MANAGEMENT FOR DOMESTIC
HOT WATER (YV2)
The HSW11 controller manages domestic hot water produc-
tion using a 3-way valve installed outside of the unit.
The production of domestic hot water is guaranteed in both
summer and winter, according to the operating limits shown
in this manual. An electric heater should be installed inside
the DHW storage cylinder to ensure the temperature does
not fall below 15/20°C in the event of extended periods of
heat pump inactivity (standby).
Domestic hot water production is only enabled if the follow-
ing conditions are satisfied:
- DHW storage temperature (sensor BT4) less than the
DHW set point (AS01) minus the hysteresis (AS04); 3-way
valve changeover to the domestic water storage;
- the time set for parameter AS10 has elapsed
- an Anti-Legionella cycle is not in progress (if activated by
parameter)
Changeover from domestic hot water production to heating
system hot water production:
- if the DHW storage temperature (sensor BT4) has reached
the DHW set point (AS01); 3-way valve changeover to
system;
- if the return water temperature (sensor BT1) has reached
the DHW set point (AS01) plus a differential (AS05) that
considers the possible temperature difference between the
domestic water storage and the system return water tem-
perature.
- if the maximum time (AS09) domestic hot water production
time has elapsed.
System diagram
For the electrical connections of the 3-way valve and the sensor BT4 in the DHW storage cylinder, see “Wiring diagram” and the
chapter “Installer connections”.
Parameter
Value Description
0
Domestic hot water management disabled
1
Domestic hot water production with heat pump only
AS00
2
Domestic hot water production with DHW storage heater only
3
Domestic hot water production with heat pump and DHW storage heater
AS01
50
Domestic hot water set point
AS04
3
Heat pump hysteresis for domestic hot water management
AS05
0
Heat pump operation differential on temperature control sensor (BT1)
AS09
60
Maximum domestic hot water production time with heat pump
AS10
15
Minimum interval between domestic hot water production requests with heat pump
1
2
3
4
5
6
7
1. Heat
pump
2. Outside air temperature sensor installed on
the unit
3. Three-way valve, managed by the unit
4. DHW
storage
5. Storage tank (if necessary)
6. Fan coil system
7. Radiant
system
The diagram is purely indicative
°C
0
-15
2,8
4,8
Outside air temperature
Refrigerant circuit pressure
bar
