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6.2.
General precautions concerning water circuit
NOTICE
Before continuing the installation of the unit, check the following
points:
In most applications this miminum water volume will have a
satisfying result.
■
The maximum water pressure is 4 bar.
■
The maximum water temperature is 80°C.
In critical processes or in rooms with a high heat load
though, extra water volume might be required.
■
Provide adequate safeguards in the water circuit to be sure that
the water pressure will never exceed the maximum allowable
working pressure (4 bar).
NOTICE
■
Shut-off valves from flexible hoses delivered with the unit should
be installed so that normal servicing can be accomplished
without draining the system.
■
Drain taps must be provided at all low points of the system to
permit complete drainage of the circuit during maintenance or
service to the unit. A drain valve is provided in the unit to drain
the water from the unit water system.
■
Be sure to provide a proper drain for the pressure relief valve to
avoid any water coming into contact with electrical parts.
■
When circulation in each space heating/radiator loop is
controlled by remotely controlled valves, it is important that
this minimum water volume is kept even if all the valves are
closed.
Example (See "6.3. Application examples" on page 9.)
A B
12 11 2 3
1
C1
11 4
Air vents must be provided at all high points of the system. The
vents shall be located at points which are easily accessible for
servicing. An automatic air purge is provided inside the indoor
unit. Check that this air purge valve is not tightened too much so
that automatic release of air in the water circuit remains
possible.
■
Take care that the components installed in the field piping can
withstand the water pressure and temperature.
■
Always use materials which are compatible with the water used
in the system and with the materials used on the unit.
■
Select piping diameter in relation to required water flow and
available ESP of the pump.
When designing the hydraulic system always consider the available
static pressure of the indoor unit.
ESP [kPa]
120
110
100
90
80
70
60
50
40
30
20
10
0
5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41
Flow [l/min]
ESP (kPa)
External static pressure (kPa)
flow (l/min)
Flow (l/min)
6
78
9
10
M3
T3
M2
T2
M1
12
5
T1
1
2
3
4
5
6
7
8
9
10
11
12
C1
M1...M3
Outdoor unit
Indoor unit
Refrigerant heat exchanger
Water heat exchanger
Compressor
Pump
Shut-off valve
Collector (field supply)
By-pass valve (field supply)
Radiator (field supply)
Electronic expansion valve
Indoor unit refrigerant stop valve
Remote controller
Individual motorized valve to control loop radiators (field
supply)
T1...T3 Individual room thermostat (field supply)
A Installation space
B Living room
Without 3-way valve
Including 3-way valve
Maximum external static pressure if ΔT=10°C (heating)
Maximum external static pressure if ΔT=5°C (heating)
INFORMATION
■
The ESP curve is the maximum ESP curve. The pump
of the indoor module is inverter controlled and
controls to have a fixed ΔT between return and leaving
water temperature.
■
In case of installing a domestic hot water tank there is
an additional pressure drop over the 3-way valve
(delivered as accessory with the tank).
Check that the total water volume in the installation, excluding the
internal water volume of the unit, is 20 l minimum.
Installation manual
8
HXHD125A7V1B
VRVIII system indoor unit
4PW62584-1A – 11.2010