Section 8: OperationPage 42
8.4 Frost Protection
Frost protection can be activated when the heat pump is in OFF mode.
This is based on either:
• Outdoor air temperature - refer to Section 8.4.1 and Figure 8-16.
• Flow water temperature - refer to Section 8.4.2 and Figure 8-17.
• Room air temperature - refer to Section 8.4.3 and Figure 8-18.
This function is not required if ethylene glycol (heating system antifreeze) is
used in the heating system water. Refer to Section 3.10.3 for guidance on how
to switch off the frost protection function.
8.4.1 Frost Protection based on Outdoor Air Temperature
This frost protection function is always active, even when the heat pump is not
operating (but the mains supply is switched on).
The water pump is activated if the outdoor air temperature (measured by the
heat pump outdoor temperature sensor) is less than the start temperature -
parameter 4311 (default: 4°C).
It is deactivated when the outdoor air temperature reaches ‘outdoor air
temperature set point + Hysteresis’ - parameter 4311 plus the hysteresis
parameter 4312 (default: 7°C).
The ‘frost protection’ symbol ( ) will be displayed on the remote controller
screen when this frost protection function is in operation.
Under low ambient air conditions the water pump may operate for an
extended period to provide frost protection when the heat pump is not
operating, e.g. possibly throughout the night, until the heat pump starts the
following morning.
Whilst the water pump may operate for long periods, when the prevailing
conditions dictate, the cost to protect the heat pump from freezing is small due
to the low water pump power consumption.
8.4.2 Frost Protection based on Flow Water Temperature
This frost protection function is always active, even when the heat pump is not
operating (but the mains supply is switched on).
The water pump is activated if the flow water temperature is less than the start
temperature - parameter 4321 (default 4°C).
It is deactivated when the flow water temperature reaches ‘flow water
temperature set point (parameter 4321) + hysteresis - parameter 4322
(default 3°C)’.
The ‘frost protection’ symbol ( ) will be displayed on the remote controller
screen when this frost protection function is in operation.
Under low ambient air conditions the water pump may operate for an
extended period to provide frost protection when the heat pump is not
operating, e.g. possibly throughout the night, until the heat pump starts the
following morning.
Whilst the water pump may operate for long periods, when the prevailing
conditions dictate, the cost to protect the heat pump from freezing is small due
to the low water pump power consumption.
8.4.3 Frost Protection based on Room Air Temperature
This frost protection function is always active, even when the heat pump is not
operating (but the mains supply is switched on).
The water pump is activated if the room air temperature (measured by the heat
pump remote controller) is less than the start temperature - parameter 4301
(default: 14°C).
It is deactivated when the room air temperature reaches ‘room air temperature
set point + Hysteresis’ - parameter 4301 plus the hysteresis parameter 4302
(default: 1°C).
The ‘frost protection’ symbol ( ) will be displayed on the remote controller
screen when this frost protection function is in operation.
Under low room air conditions the water pump may operate for an extended
period to provide frost protection when the heat pump is not operating, e.g.
possibly throughout the night, until the heat pump starts the following morning.
Whilst the water pump may operate for long periods, when the prevailing
conditions dictate, the cost to protect the heat pump from freezing is small due
to the low water pump power consumption.
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