84 Aquarea air-to-water heat pumps - Planning and installation manual - 01/2018
Planning
85
Aquarea air-to-water heat pumps - Planning and installation manual - 01/2018
Planning
pipelines lead to a lower heating capacity. And not the least, besides the heat pump power, its
water inow temperature at standard outside temperature is also decisive for the correct choice
of the heat pump.
On the other hand, Aquarea heat pumps have an internal E-heating element, which can addi-
tionally provide the heat supply at very low outside temperatures.
For calculating the total heating capacity required, all the above-mentioned criteria should be
taken into consideration together:
1. Standard outside temperature
2. Standard heating load
3. Tank charging (time required for hot water preparation with the heat pump)
4. Possible EVU locking period (e.g. 1 x per day for 2 hours)
5. Pipeline correction factor
Heating capacity ≥
Standard heating load x 24 h
(24 h - tank charging - EVU locking period) x pipeline correction factor
!
IMPORTANT
In new buildings, a building drying up generally takes place in the initial two years after occupa-
tion, when the humidity from the building phase escapes from the building; during this time the
heat requirement is higher than after the phase of building drying. This increased heat require-
ment can be covered by the internal E-heating element heat pump.
Example
● Residential house in Frankfurt/Main with a heating load of 9.6 kW for a standard
outside temperature of θe = -12 °C
● Hot water preparation for four persons with standard comfort expectation (45 litres
per person and day at 45 °C tapping temperature or 1.8 kWh): 4 x 1.8 = 7.2 kWh
per day. For the hot water preparation, a heat pump with a heating capacity of 9.6 kW
would need 7.2 kWh / 9.6 kW = 0.75 h operation. Rounding off, this gives a take
charging of 1 hour (1 h).
● The line correction factor is yielded on the basis of a connection distance of 15 m
(single length) as the mean value of 0.95 and 0.90 for a line correction factor = 0.93
Total heating capacity ≥
9.6 x 24 h
=
230.4
10.77 kW
(24 h – 1 h) × 0.93 21.39
The additional consideration of a EVU locking time of 2 hrs per day results in:
Total heating capacity ≥
9,6 × 24 h
=
230.4
11.80 kW
(24 h – 1 h – 2 h) × 0.93 19.53
The calculated total heating capacity must be generated with simultaneous maintenance of the
required water inow temperature of 35 °C for underoor heating.
!
IMPORTANT
The determination of the total heating load shown can deviate a little from the detailed calcula-
tion with the Aquarea Designer, but can be used quickly as a rule-of-thumb guide and without
using a calculation programme.
The gure below shows the characteristics for a selection of split systems of the Aquarea LT
series with different heating capacity. By plotting the design point (total heating capacity = 12
kW at θe = -12 °C) and the point after which there is no heating requirement (heating limit tem-
perature, in this case 20 °C) and the connection of the two points, it is possible to determine the
bivalence point.
Performance characteristic of a selection of Aquarea split systems
0
2
4
6
8
10
12
14
16
18
-20-15 -10-50 510152
5
Heizleistung (kW)
Außentemperatur (°C)
SDC09/35 °C
SDC12/35 °C
SDC16/35 °C
SDC09/55 °C
SDC12/55 °C
SDC16/55 °C
Ausleg.Bivalenz.Heiztrenz
Design point
Bivalence point
Heating limit temperature
Inow temperature 35 °C
0
2
4
6
8
10
12
14
16
18
-20-15 -10-50 510152025
Heizleistung (kW)
Außentemperatur (°C)
SDC09/35 °C
SDC12/35 °C
SDC16/35 °C
SDC09/55 °C
SDC12/55 °C
SDC16/55 °C
Ausleg.Bivalenz.Heiztrenz
WH-SDC09H3E8 + WH-UD09HE8
0
2
4
6
8
10
12
14
16
18
-20-15 -10-50 510152025
Heizleistung (kW)
Außentemperatur (°C)
SDC09/35 °C
SDC12/35 °C
SDC16/35 °C
SDC09/55 °C
SDC12/55 °C
SDC16/55 °C
Ausleg.Bivalenz.Heiztrenz
WH-SDC12H9E8 + WH-UD12HE8
0
2
4
6
8
10
12
14
16
18
-20-15 -10-50 510152025
Heizleistung (kW)
Außentemperatur (°C)
SDC09/35 °C
SDC12/35 °C
SDC16/35 °C
SDC09/55 °C
SDC12/55 °C
SDC16/55 °C
Ausleg.Bivalenz.Heiztrenz
WH-SDC16H9E8 + WH-UD16HE8
Inow temperature 55 °C
0
2
4
6
8
10
12
14
16
18
-20-15 -10-50 510152025
Heizleistung (kW)
Außentemperatur (°C)
SDC09/35 °C
SDC12/35 °C
SDC16/35 °C
SDC09/55 °C
SDC12/55 °C
SDC16/55 °C
Ausleg.Bivalenz.Heiztrenz
WH-SDC09H3E8 + WH-UD09HE8
0
2
4
6
8
10
12
14
16
18
-20-15 -10-50 510152025
Heizleistung (kW)
Außentemperatur (°C)
SDC09/35 °C
SDC12/35 °C
SDC16/35 °C
SDC09/55 °C
SDC12/55 °C
SDC16/55 °C
Ausleg.Bivalenz.Heiztrenz
WH-SDC12H9E8 + WH-UD12HE8
0
2
4
6
8
10
12
14
16
18
-20-15 -10-50 510152025
Heizleistung (kW)
Außentemperatur (°C)
SDC09/35 °C
SDC12/35 °C
SDC16/35 °C
SDC09/55 °C
SDC12/55 °C
SDC16/55 °C
Ausleg.Bivalenz.Heiztrenz
WH-SDC16H9E8 + WH-UD16HE8
For a monovalent operating mode of the heat pump, the determined heating capacity of 12 kW itself
could not be generated with a 16 kW Aquarea heat pump of the LT series. For reasons of economy
and because very low outside temperatures only occur on scattered occasional days in the year, the
heat pump is designed as a bivalent heating system. As the second heat source, which is used as
a booster heater, consists of an internal E-heating element heat pump, the heat pump is operated
mono-energetically. Below the outside temperature of the bivalence point of -7 °C, the remaining
heating capacity is generated by the E-heating heat pump element. Up to an outside temperature,
the Aquarea heat pump runs in the monovalent mode.
The following heat pumps of the Aquarea LT series can be considered for the split systems due
to the intersection with the performance characteristic at -7 °C and a water inow temperature of
35 °C.
● WH-SDC12H9E8 + WH-UD12HE8 (three- phase)
● WH-SDC16H9E8 + WH-UD16HE8 (three- phase)
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