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6 - APPLICATION DATA
6.5 - Water loop volume
6.5.1 - Minimum water loop volume
The heat pump is used in a domestic hot water application and
must heat an intermediate loop that supplies domestic hot water
via a heat exchanger. The primary loop is charged with softened
water. Regular checks must be carried out on the water system
to detect possible scale formation. The heat pump in this type of
application must never supply domestic hot water directly.
The minimum water loop volume, in litres, is given by the following
formula:
Volume (l) = CAP (kW) x N, where CAP is the nominal heating
capacity at nominal operating conditions.
Heating or domestic hot water application
61AF 022-055
61AF 075-105
This volume is required to obtain temperature stability and
precision.
To achieve this volume, it may be necessary to add a storage tank
to the circuit. This tank should be equipped with baffles to allow
mixing of the fluid (water or brine). Please refer to the examples
below.
Bad
Bad
6.5.2 - Expansion tank volume
Units with hydraulic module do not incorporate an expansion tank.
This must be included in the water loop.
The table below gives the buffer tank volume that must be
provided, based on the water loop volume, the fluid used and its
concentration.
Expansion tank volume required
Pure water
10 % ethylene glycol
20 % ethylene glycol
30 % ethylene glycol
40 % ethylene glycol
(1) Calculation based on a charge temperature of 10°C.
N
5,0 l
3,0 l
Good
Good
% of water loop
volume
(1)
3,0
3,0
3,5
3,8
4,2
6.6 - Plate heat exchanger pressure drop
curves
For pure water at 20°C
30
25
20
15
10
5
0
0
1
Water flow rate, l/s
1
61AF 022
2
61AF 030
3
61AF 035
4
61AF 045
50
40
30
20
10
0
0
2
Water flow rate, l/s
1
61AF 055
2
61AF 075
3
61AF 105
4
3
2
1
2
3
4
2
1
4
6
8
5
3
10
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