Domestic Hot Water Mode; Master/Slave Up To 4 Units - Riello NexPolar Series Installation And Technical Service Instructions

FUNCTIONS
WINTEr PoSITIoN For UNIT WITH HYDroNIC MoDUlE
Unit
Open
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When the unit switches to winter mode, based on the local at-
mospheric conditions, it is necessary to do the following:
— Add ethylene glycol or propylene glycol in a concentration
suitable for protecting the system down to a temperature 10
K lower than the lowest temperature likely to occur at the in-
stallation site.
— If the unit is not expected to be utilized for an extended pe-
riod of time, it is recommended to empty it, and to load eth-
ylene glycol or propylene glycol into the heat exchanger as a
safety precaution, using the connection for the water intake's
impurity discharge valve.
— At the start of the next season, fill the unit with water and add
an inhibitor.
— In order to install auxiliary equipment, the installer must
comply with the basic standards, particularly with regard
to the minimum and maximum flow rates, which must fall
within the values indicated in the operating limits table (ap-
plication data).
— In order to prevent corrosion due to differential aeration, the
drained heat transfer circuit must be entirely filled with ni-
trogen for a month. If the heat transfer fluid is not compliant
with the manufacturer's indications, the nitrogen load must
be added immediately.
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It should be noted that the "water freeze protection" function
and the "home freeze protection" function are two different
modes. The water freeze protection function is used to reduce
the risk of the water heat exchanger and water pipes freezing,
while the home freeze protection function is used to maintain
the minimum temperature within the rooms.
4.5

Domestic hot water mode

The main components necessary for the production of domestic hot
water are the following:
a. DHW diverter valve
The units are able to control a diverter valve in order to manage
applications such as domestic hot water tanks. When domestic
hot water is required, the operating logic activates a diverter valve,
which directs the hot water into the accumulation tank.
For the valve's characteristics and electrical connections, please re-
fer to the instructions furnished along with the accessory.
Open
System
Off
50
b. DHW temperature sensor or a thermostat
Based on the configuration, the DHW option can be controlled with
a temperature sensor or thermostat.
DHW can be produced when:
— The DHW only mode is selected and there are no DHW require-
ments (temperature conditions)
— The DHW program is enabled and there are DHW requirements
(temperature conditions), and the operating time in this
mode is less than the DHW's maximum operating time [P707]
c. DHW electric heater
When the unit's operation in DHW mode is requested (if config-
ured), the DHW electric heater can be utilized to provide domestic
hot water. The discrete output is capable of controlling a contactor
(not provided).
The electric heater is activated when the tank's temperature is be-
low the DHW setpoint and the following conditions are met:
— the OAT is below the added OAT threshold [P604]
— the OAT is above the maximum OAT for heating [P515]
— Anti-legionella mode is enabled
— Defrost mode is enabled
— In the event that the unit should experience a fault or mal-
function
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The electric heating function is deactivated when the high en-
ergy cost or load reduction modes are enabled, or in the event
of a DHW thermistor fault of malfunction.
d. Domestic water tank protection
The water inside the domestic water tank must be constantly mon-
itored in order to minimize the risk of contamination, even by the
bacteria responsible for legionella. It is therefore essential that the
user is notified of the importance of monitoring the water's tem-
perature.
• Water tank protection system
The system is programmed to heat the water in the domestic hot
water tank in such a way as to kill the existing bacteria, and to
eliminate the potential spread of legionella.
Legionella cannot survive at temperatures above 50°C. The risk of
contamination is practically non-existent when the water temper-
ature is set to 60°C.
•
Water tank protection settings
In order to protect the domestic water tank against legionella bac-
teria, the following parameters must be set:
— Anti-legionella start week day [P714]
— Anti-legionella start time [P715]
— Anti-legionella water setpoint [P405] (the anti-legionella
protection is interrupted once the water temperature reaches
the preset temperature)
e. DHW limitation mode
DHW limitation mode [P543] provides for greater sound comfort by
reducing the compressor's frequency when DHW mode is enabled.

4.6 Master/slave up to 4 units

a. installation
Master/slave installation allows for up to four units to be connected
in parallel: one master unit is capable of controlling up to three
slave units.
This type of installation must be performed using units of the same
type (only cold or reversible) and the same size (mod. 17 or 22),
equipped with hydronic kits (variable or fixed speed kits). Master/
slave operation is not compatible with domestic hot water produc-
tion.
The remote control panel can only be connected to the master unit.