Panasonic Aquarea B1 Planning And Installation Manual page 47

Planning
The values relate to the measurable value at a distance of 0.5 m from the centre of the opened
window of the room affected and requiring protection. They are mean values and may be
crossed over short sound peaks.
The measurable sound pressure level depends on the distance to the sound source and falls
with increasing distance.
5.2.1.2 Sound power level for approximate calculation of the sound pressure level
The sound power level is a quantity for rating the sound source independently of the distance
and direction of the sound propagation. It is a mathematically determinable quantity, which is
determined for individual devices in laboratory measurements under defined conditions. Based
on the sound power level of a specific device, the sound pressure level can be roughly deter-
mined at a certain distance and for corresponding sound propagation conditions for a concrete
case.
Sound propagates equally in all directions with the sound power of the sound source. The area,
through which the sound passes, increases as the distance to the sound source increases. This
results in a continuous reduction in the sound pressure level for the same sound power.
The sound pressure level is also affected by the following factors during the sound propagation.
● Shadows cast by obstacles such as buildings, walls or land formations
● Reflection on sonically hard surfaces such as walls, glass facades, buildings or
asphalted floors as well as stone flooring
● Absorption of the sound, for example by grass, bark mulch, leaves or freshly fallen
snow
● Wind can strengthen or reduce the sound pressure level (depending on the wind
direction)
A rough determination of the sound pressure level L
heat pump can be calculated with the following formula and based on the sound power level
L :
Waeq
( )
Q
L = L + 10 × log
Aeq WAeq
4 × π × r²
This only requires the direction factor Q in addition, which takes into account the spatial propa-
gation conditions of the sound source.
Direction factor Q for different arrangements of the sound source
Sound In half room
propagation
Q = 2
Arrangement
88
Aquarea air-to-water heat pumps - Planning and installation manual - 01/2018
at a certain location at a distance r to the
Aeq
In quarter room In one-eighth room
4 8
Example
The outdoor unit WH-UD12HE5 of a split system has a sound power level of 67 dB(A) and is set
up such that the sound can propagate in the quarter room (Q = 4). The sound pressure level at
10 m distance is then:
(
L (10 m) = 67 dB (A) + 10 × log
Aeq
4 × π × 10²
At a distance of 20 m, the sound pressure level is however still only:
(
L (20 m) = 67 dB (A) + 10 × log
Aeq 4 × π × 20²
The sound pressure level can roughly be calculated even more easily by using the table below,
by subtracting the table value from the device-specific sound power level
→ 4.6.3.3 Technical data (compact systems), p.
(split systems), p. 16,
Table for rough determination of the sound pressure level based on the sound power
level
Guide factor Q 1
2 -8
4 -5
5
-2
!
IMPORTANT
The sound propagation can be facilitated or reduced by selecting the installation location. Avoid
setting up on sonically hard floor surfaces. Sound propagation can be reduced further by con-
struction obstacles, but the air flow should not be hindered.
Choice of the blowing direction of the outdoor or compact device should preferably be towards
the road, because neighbouring rooms requiring protection rarely face in this direction.
If in doubt, use an acoustician's services.
Aquarea air-to-water heat pumps - Planning and installation manual - 01/2018
Planning
)
4
= 42 dB (A)
)
4
= 36 dB (A)
(→ 4 Technical data
50).
Distance from the sound source (m)
2 4 5 6 8 10 12
-14 -20 -22 -23.5 -26 -28 -29.5
-11 -17 -19 -20.5 -23 -25 -26.5
-8 -14 -16 -17.5 -20 -22 -23.5
15
-31.5
-28.5
-25.5
89