Panasonic Aquarea WH-SDC09H3E5-1 - Expansion Vessel; Heating Water Quality

102 Aquarea air-to-water heat pumps - Planning and installation manual - 01/2018
Planning
103
Aquarea air-to-water heat pumps - Planning and installation manual - 01/2018
Planning
5.3.4 Special points related to cooling
Hydraulically, a heat pump system with cooling does not differ from a purely heating system.
You however need the generated amount of heat of the heat pump system to calculate the
annual performance number, which is why you have to use what are called “climate counters” to
correctly determine the amount of heat which record the amount of heat as well as the amount
of cold.
5.3.5 Expansion vessel
The Aquarea heat pumps have an integral expansion vessel with a model-specic volume of 6
or 10 litres (see table) and an initial pressure of 1 bar.
The volume of the expansion vessel is adequate for heating systems whose total water quantity
and its static height (difference of the highest point of the system to the expansion vessel) must
not exceed dened limits.
Model-specic limit values for the integrated expansion vessel
WH-MDC05H3E5
WH-MDC07H3E5
WH-MDC09H3E5
All other models
Expansion vessel volume l 6 10
Initial pressure bar 1 1
Total water quantity in the heating system (max.) l 150 200
Static height m 7 7
Pressure stage safety valve (max.) bar 3 3
In case the total quantity of water is greater than 150 or 200 litres, or greater static heights
are required, it is necessary to maintain the pressure by means of an expansion vessel to be
installed on site. Generally, pay attention to the pressure stage of the safety valve. This is given
in the technical data and is maximum 3 bar.
The following criteria must be taken into consideration when designing the necessary expansion
vessel nominal volume V
N
.
Nominal volume V
N
(Nominal volume of the expansion vessel)
Expansion volume V
e
(Expansion volume of the expansion vessel)
System volume V
A
(Total volume of the heating system)
Sample volume V
V
(Volume of the water trap)
Maximum temperature T
max
(highest temperature in the system e.g. 60 °C)
Final pressure of the safety valve p
e
(depends on the safety valve, max. 2.5 bar)
Initial pressure of expansion vessel p
0
(Initial pressure 1 bar)
V
N
= (V
e
+ V
V
)
p
e
+ 1
p
e
– p
0
1. The expansion volume V
e
is obtained from the system volume and the maximum
temperature from the coefcient of expansion of water according to the following
table:
T
max
(°C) 40 50 60 70 80 90 100
n (%) 0.93 1.29 1.71 2.22 2.81 3.47 4.21
Percentage expansion of water:
V
e
= V
A
n
100
2. The volume of the water trap V
V
can be calculated in a simplied manner as
follows:
V
V
= 0.2 × V
N
(for a nominal volume V
N
< 15 litres) or
V
V
= 0.005 × V
A
(for a nominal volume V
N
> 15 litres, where V
V
≥ 3 litres)
3. The nal pressure of the safety valve p
e
is obtained from the response pressure of
the safety valve minus a tolerance of 0.5 bar:
p
e
= Safety valve response pressure – 0.5 bar
4. Select the initial pressure p
0
such that it corresponds to the static height of the
heating system and an allowance of max. 0.5 bar. 10 metres static height corre-
sponds to 1 bar. Adjust the initial pressure of the Aquarea expansion vessel, if
necessary.
i
Note
The calculation of the expansion vessel is done according to EN 12828 “Heating systems in
buildings - Planning of Hot Water - Heating Systems” The manufacturer’s design programs for
expansion vessels can generally be used for the design, depending on the local requirements.
They also determine the required initial pressures to be set on the expansion vessel.
5.3.6 Heating water quality
CAUTION
Danger of damage to pipelines due to corrosion
In the case of open water systems, the oxygen entry can cause excessive corrosion of the pipe-
lines and the subsequent problems in operation.
► Install Aquarea heat pumps only as closed systems without direct contact of the heat-
ing water to the ambient air.
To avoid damage to the heating system and to the heat pump, respect the corresponding Euro-
pean and national requirements (example of Germany: Guideline VDI 2035 “Avoiding damage
in hot water heating systems - Stone formation in drinking water heating and hot water heating
systems”). Furthermore, the heating system is to be thoroughly purged before lling with heating
water.