Hitachi YUTAKI Series Installation And Operation Manual page 112

UNIT CONTROLLER
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Solar combination - Total control
ΔT connection:
• Allows to specify a difference temperature
between tank and Panel temperature to
allow solar operation. Solar operation is
allowed in case Panel temperature is "ΔT
connection" ºC above tank temperature.
ΔT disconnection:
• Allows to specify a difference temperature
between tank and Panel temperature to
stop solar operation. Solar operation is not
allowed in case Panel temperature is "ΔT
connection"ºC below tank temperature
Panel antifreeze temperature:
• Minimum Solar panel temperature at
which Solar Pump is switched ON in
order to protect system against frost
formation at pipes due to low ambient
temperature.
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Boiler combination
Minimum ON time:
• Time that must pass before stop
boiler after being switched ON
Minimum OFF time:
• Time that must pass before start
boiler after being switched OFF
Wait time for DHW:
• Delay time to start Boiler for DHW
in case all conditions allow Boiler to
start after HP has been started for
DHW.
102 PMML0510 rev.1 - 10/2019
DHW maximum time:
• Maximum time YUTAKI allows to heat tank by
means Solar. At the end of this time Solar pump is
stopped regardless temperature conditions at Solar
Panel.
DHW minimum time:
• Minimum Time solar operation cannot be performed
once it has been stopped due to DHW Maximum
Time or due to low temperature at solar panel.
DHWT maximum storage temperature:
• Maximum DHW temperature that allows
Solar operation.
Panel minimum temperature:
• Minimum temperature of the solar Panel to
allow Solar operation
Panel overheat temperature:
• Maximum panel operation temperature
at which Solar Pump is set to off in case
Panel sensor reads a temperature above
this value in order to protect system.
• In case that the solar pump is stopped due
to panel overheat temperature, the YUTAKI
unit sets solar overheat output to high state
provided that this function has been setup
as described in "8.6.2.9 Setup of inputs,
outputs and sensors"
Bivalent point:
• Boiler is allowed to operate in
case ambient temperature is
below this value
Combination mode:
• Serial: Boiler operates in series with the heat-pump. The
boiler provides additional peak load capacity and works
together with the HP
• Parallel: Boiler operates in parallel with the heat pump.
The boiler provides the full heating requirements. In case
Boiler is ON, HP is not allowed to operate
Supply setting offset:
• Setting offset for Boiler. Higher
values imply earlier stoppage
of Boiler and vice versa.
Waiting time:
• Delay time to start Boiler in case all conditions allow
Boiler to start after HP has been started for Space
Heating
DHW by boiler:
• Control to allow heat
DHW by means Boiler