Table 4: Different Operating Modes - Riello NXHP Series Installation, Operation And Maintenance Instructions

4 -OPERATION
4.2.2 - Operating modes
The user can normally choose one of three available operating
modes, i.e. cooling, heating or domestic hot water production only.
Other modes such as booster cooling or booster heating, purge,
and drying, can be selected only with service access level.
The unit may run in the following modes:
■ Off: Unit is requested to stop.
■ Cool: Unit is requested to run in Cooling mode.
■ Heat: Unit is requested to run in Heating mode.
■ DHW Only: Unit is requested to run in DHW mode Only.
■ Booster Cool: Unit is requested to run in Cooling mode at
maximum compressor frequency.
■ Booster Heat: Unit is requested to run in Heating mode at
increased compressor frequency.
■ Purge: Water pump is requested to run in order to purge the
hydraulic circuit.
When Cooling mode is selected, the chiller or heat pump will
operate in the Cooling mode in order to cool the water loop to the
selected temperature.
When the heat pump is in Heating mode, the heat pump heats
the water loop to the selected temperature. When the outdoor air
temperature is very low, electric heaters or boiler heating can be
used in order to satisfy the heating demand.
When DHW Only is requested, the unit is not allowed to operate
in cooling or heating modes.
It is also possible for the unit to operate in DHW mode when
heating mode or cooling mode is selected, according to schedule
/ temperature condition / maximum runtime.
When the system is in the Off mode, the compressor and the pump
are stopped (except for home anti-freeze protection and water
freeze protection, refer to § 4.2.6 Home anti-freeze protection and
4.2.7 Water freeze protection).
4.2.3 - Operating mode control
The operating mode selection may differ depending on access
level and the use of communication methods, i.e. WUI display,
Proprietary Protocol communication, or JBus communication.
In the following sections of this document,the configuration steps
are the same for all of these three communication methods, except
when the configuration is described with WUI direct access.
a - WUI control
If the unit is fitted with a user interface, the mode selection can be
done by direct access on WUI.
When the unit is Off, press the Mode key to wake up the user
interface and then press the Mode key successively to select the
required operating mode.

Table 4: Different operating modes

System Mode
Off
Cool
Heat
DHW only
Booster Cool
(1)
Booster Heat
(1)
Purge
(1)
Drying
(1)
(1) Service access level only (with password 0120).
For more information on user interface, please refer to the WUI
end user manual.
WUI display Icon
- [no icon]
[steady icon]
[steady icon]
[steady icon]
[flashing fast]
[flashing fast]
[flashing fast]
[flashing slow]
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