96 Aquarea air-to-water heat pumps - Planning and installation manual - 02/2022
Planning
5
For calculating the total heating capacity required, all the above-mentioned criteria should be taken
into consideration together:
1. Design outside temperature
2. Design heat load
3. Tank charging (time required for domestic hot water production with the heat pump)
4. Possible electricity shutdown times imposed by the utility company (e.g. 1 x per day
for 2 hours)
5. Pipe length correction factor
Heating capacity ≥
Design heat load x 24 h
(24 h – tank charging – shutdown times) x pipe length correction factor
!
IMPORTANT
In new buildings, a phase of building drying usually takes place in the initial two years after
occupation, when the humidity from the construction phase escapes from the building; during this
time the heat demand is higher than after the phase of building drying. This increased heat demand
can be covered by the heat pump’s internal electric backup heater.
Example
● Residential house in Frankfurt/Main with a heat load of 9.6 kW for a design outside
temperature of θe = -12 °C
● Domestic hot water production for four persons with normal 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 domestic hot water production, a heat pump with a heating capacity
of 9.6 kW would need 7.2 kWh / 9.6 kW = 0.75 h operation. Rounding up, this results in
a tank charging time of 1 hour (1 h).
● The pipe length correction factor is yielded on the basis of a connection distance of 15 m
(one way) as the mean value of 0.95 and 0.90 for a pipe length correction factor = 0.93
Total heating capacity required ≥
9.6 x 24 h
=
230.4
10.77 kW
(24 h – 1 h) × 0.93 21.39
The additional consideration of an electricity shutdown time of 2 hrs per day results in:
Total
heating capacity
required
≥
9,6 × 24 h
=
230.4
11.80 kW
(24 h – 1 h – 2 h) × 0.93 19.53
The calculated total heating capacity required must be generated while maintaining the supply
water temperature of 35 °C required for underoor heating.
!
IMPORTANT
The determination of the total heating capacity required, shown above, can deviate a little from the
detailed calculation with the Aquarea Designer, but can be used quickly as a rule-of-thumb guide
and without using a calculation programme.
5.1.7 Cooling
For Aquarea heat pump models with cooling function (High Performance and T-CAP series),
the cooling function must be activated by a qualied service technician during commsissioning.
After that, the cooling mode can be switched on/o and controlled by the end user via the remote
controller.
25.11.2021, cH
I deleted the example and graphic for determing the
heat pump matching the calculated heat demand,
because it would have taken me an awful lot of
time to re-create the graphic with the current
models.
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