Installation manual
9
EWAQ+EWYQ009~0 EWAQ+EWYQ009~013ACW1
Packaged air-cooled water chillers and packaged
reversible air to water heatpumps
4PW51587-1A
Checking the water volume and expansion vessel
pre-pressure
The unit is equipped with an expansion vessel of 10 litre which has a
default pre-pressure of 1 bar.
To assure proper operation of the unit, the pre-pressure of the
expansion vessel might need to be adjusted and the minimum and
maximum water volume must be checked.
1
Check that the total water volume in the installation, excluding
the internal water volume of the unit, is 20 l minimum. Refer to
"Technical specifications" on page 25
volume of the unit.
Operation range
2
Using the table below, determine if the expansion vessel pre-
pressure requires adjustment.
3
Using the table and instructions below, determine if the total
water volume in the installation is below the maximum allowed
water volume.
Calculating the pre-pressure of the expansion vessel
The pre-pressure (Pg) to be set depends on the maximum
installation height difference (H) and is calculated as below:
Pg=(H/10+0.3) bar
Checking the maximum allowed water volume
To determine the maximum allowed water volume in the entire circuit,
proceed as follows:
1
Determine for the calculated pre-pressure (Pg) the
corresponding maximum water volume using the graph below.
2
Check that the total water volume in the entire water circuit is
lower than this value.
If this is not the case, the expansion vessel inside the unit is too small
for the installation.
Example 1
The unit is installed 5 m below the highest point in the water circuit.
The total water volume in the water circuit is 100 l.
In this example, no action or adjustment is required.
Example 2
The unit is installed at the highest point in the water circuit. The total
water volume in the water circuit is 350 l.
Result:
■
Since 350 l is higher than 280 l, the pre-pressure must be
decreased (see table above).
■
The required pre-pressure is:
Pg = (H/10 + 0.3) bar = (0/10 + 0.3) bar = 0.3 bar
■
The corresponding maximum water volume can be read from
the graph: approximately 410 l.
■
Since the total water volume (350 l) is below the maximum water
volume (410 l), the expansion vessel suffices for the installation.
Setting the pre-pressure of the expansion vessel
When it is required to change the default pre-pressure of the
expansion vessel (1 bar), keep in mind the following guidelines:
■
Use only dry nitrogen to set the expansion vessel pre-pressure.
■
Inappropriate setting of the expansion vessel pre-pressure will
lead to malfunction of the system. Therefore, the pre-pressure
should only be adjusted by a licensed installer.
A
Outdoor temperature
°C DB
°C dry bulb
LEWT
Leaving evaporator water temperature
LCWT
Leaving condenser water temperature
In most applications this minimum water volume will
have a satisfying result.
In critical processes or in rooms with a high heat load
though, extra water volume might be required (40 l).
Installation
height
difference
(a)
(a) Installation height difference: height difference (m) between the highest point of
the water circuit and the unit. If the unit is located at the highest point of the
installation, the installation height is considered 0 m.
Water volume
≤
280 l (EWAQ)
>280 l (EWYQ)
≤
7 m
No pre-pressure adjustment
required.
Actions required:
• pre-pressure must be
decreased, calculate
according to
pre-pressure of the
expansion vessel"
• check if the water volume is
lower than maximum allowed
water volume (use graph
below)
>7 m
Actions required:
• pre-pressure must be
increased, calculate
according to
pre-pressure of the
expansion vessel"
• check if the water volume is
lower than maximum allowed
water volume (use graph
below)
Expansion vessel of the unit
too small for the installation.
5
0
0
10
0
0
–5
7
35
–15
46
22
50
35
25
20 l
H
2
O
20 l
H
2
O
40 l
40 l
= pre-pressure
= maximum water volume
0.3
0.5
1
1.5
2
2.5
100
50
0
20
150
200
250
300
350
400
450
maximum water volume [l]
pre-pressure [bar]
Содержание EWAQ-ACV3
Страница 29: ...NOTES NOTES ...
