• Heat reclaim ventilation • VAM-FA/FB
1
13
• Ventilation • Heat reclaim ventilation
48
13
Installation
13 - 2 Reducing operating sound
13 - 2 - 1 Points for reducing operating sound
1. Operating sound heard from the air discharge outlet can be
reduced just by applying sound-insulating material to the SA
(indoor air supply) duct.
2. Operating sound can be reduced more effectively by applying
sound-insulating material to a portion of the SA duct near the unit
body than that near the air suction / discharge grille.
13 - 2 - 2 Taking measures to reduce operating
sound heard from attic-installed
equipment and air ducts.
1. When installing large air volume models (650 m
3
/ h or more),
avoid the following wherever possible if it is expected to be
necessary to apply sound-insulating material to them. (Fig.1)
Making the duct diameter extremely small
(Example:
φ
250
→
φ
150,
φ
200
→
φ
100)
Making the duct extremely bent using bellows (in particular,
connecting bellows to the air discharge outlet of the unit body)
Making opening holes on the ceiling
Hanging the unit on a material which does not have enough
hanging strength
See “Precautions for installing and handling the unit” on pages
77 and 87.
2. Take the following sound reduction measures. (Fig.2)
Use a sound-insulating (low-permeability-to-sound) ceiling.
Note:
Some sound-insulating ceilings are not very effective in reducing
low-frequency element of the operating sound.
Place a sound-reducing material under the source of the
operating sound.
Note:
When using a sound-insulating sheet, it is necessary to have the
entire body of the unit covered with it. Note, however, that some
models do not allow the use of a sound-insulating sheet because it
may badly affect the ventilation of their radiation heat.
13 - 2 - 3 Reducing operating sound heard from
the air discharge outlet (suction inlet)
1. Use the following recommended optional accessories to reduce
operating sound heard from attic-installed duct type models.
(Fig.3)
Sound-eliminating box (Silencer)
Flexible duct
Sound-eliminating air suction / discharge grille
2. If the above accessories do not give satisfactory effect or when an
attic-installed cassette type model is used, take the following
measure.
Apply a sound-absorbing material to the interior of the room.
3. To reduce the air flow sound heard from the air discharge outlet
(suction inlet) of an attic-installed duct type model, use a small
diameter flexible duct, which excels in sound absorptivity, for
greater sound reduction effect.
Branched duct (for letting air flow through two ducts to slow
down its speed before it reaches the air discharge outlets
(sunction inlets))
Flexible duct
4. Installation of the unit with the source of its operating sound
located at a corner of a room will be a partially effective sound
reduction measure; it will keep persons in the center of the room
free from the annoying operating sound, with those in the corner
of the room kept annoyed by the operating sound. To avoid this,
try to find the best installation place from which the operating
sound is least heard by everyone in the room.
The air suction and discharge grille may give out operating
sound higher by 8 to 11 phons than of the HRV units body.
When installing this unit in a quiet place, take measures to
reduce operating sound.
EA
OA
RA
SA
(HC0054)
Air suction /
discharge
grille
Apply sound-insulating
material to the SA duct.
Flexible duct
HRV units
(HC0055)
EA
OA
RA
SA
Air supply
and exhaust
grille
Apply sound-insulating material here
for effective operating sound reduction.
Flexible duct
HRV units
1
4
3
2
(HC0056)
Fig.1
1
2
3
4
(HC0057)
1
2
Fig.2
1
2
(HC0058)
1
3
2
Fig.3
1
2
3
(HC0059)
1
Fig.4
1
1
(HC0060)
1
2
Fig.5
2
