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It is strongly recommended to install an additional filter on the
heating water circuit. Especially to remove metallic particles
from the field heating piping, it is advised to use a magnetic or
cyclone filter, which can remove small particles. Small particles
may damage the unit and will NOT be removed by the standard
filter of the heat pump system.
If air or dust gets into the water circuit, problems may occur. To
prevent this:
Only use clean pipes
Hold the pipe end downwards when removing burrs.
Cover the pipe end when inserting it through a wall, to
prevent dust and/or particles entering the pipe.
Use a decent thread sealant to seal connections.
For safety reasons, it is NOT allowed to add any kind of glycol to
the water circuit.
The installation must be in compliance with the applicable
legislation and may require additional hygienic installation
measures.
In accordance with the applicable legislation, it may be
necessary to install thermostatic mixing valves.
6.2.3.
Formula to calculate the expansion vessel pre-pressure
The pre-pressure (Pg) of the vessel depends on the installation
height difference (H) ft (m):
Pg=4.35+(H (ft)/2.31) (psi) (0.3+(H (m)/10) (bar))
6.2.4.
To check the water volume
The indoor unit has an expansion vessel of 2.6 gallon (10 liter) with a
factory set pre-pressure of 14.5 psi (1 bar).
To make sure that the unit operates properly:
You must check the minimum and maximum water volume.
You might need to adjust the pre-pressure of the expansion
vessel.
Minimum water volume
Check that the total water volume in the installation is minimum
5.3 gallon (20 liter), the internal water volume of the indoor unit NOT
included.
INFORMATION
In critical processes, or in rooms with a high heat load,
extra water might be required
NOTE
When circulation in each space heating loop is controlled
by remotely controlled valves, it is important that the
minimum water volume is guaranteed, even if all of the
valves are closed.
HXY48TAVJU
VRV System indoor unit
3P616151-1A – 2021.12
a
b
c
e
d e
a Outdoor unit (VRV)
b Indoor unit HXY48
c Heat exchanger
d Pump
e Shut-off valve
f Collector (field supply)
g By-pass valve (field supply)
FHL1...3 Floor heating loop (field supply)
T1...3 External thermostat which will be used with demand PCB
(field supply)
M1...3 Individual motorised valve to control loop FHL1...3
(field supply)
Maximum water volume
Use the following graph to determine the maximum water volume for
the calculated pre-pressure.
a
35.0
30.0
25.0
20.0
15.0
10.0
5.0
0.0
0.0
20.0
40.0
Unit
a Pre-pressure: (PSI)
b Max Water Volume (gal)
Example: Maximum water volume and expansion vessel pre-
pressure
Installation
Water volume
height
≤74 gal (280 l)
(a)
difference
≤23 ft (7 m)
No pre-pressure
adjustment is required.
>23 ft (7 m)
Do the following:
• Increase the
pre-pressure.
• Check if the water
volume does NOT
exceed the maximum
allowed water volume.
(a) This is the height difference (m) between the highest point of the water circuit and
the indoor unit. If the indoor unit is at the highest point of the installation, the
installation height is 0 m.
f
g
T1
T2
T3
M1
M2
M3
FHL1
FHL2
FHL3
60.0
80.0
100.0
>74 gal (280 l)
Do the following:
• Decrease the
pre-pressure.
• Check if the water
volume does NOT
exceed the maximum
allowed water volume.
The expansion vessel of
the indoor unit is too small
for the installation.
Installation and operation manual
b
9
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