39
Horizontal units
Use the following guidelines for layout of Aquazone hori-
zontal units to minimize noise:
1. To select quietest equipment, obtain sound power
ratings in accordance with latest standards from
manufacturers.
2. Do not locate units over a space with a required noise
criteria of 40 or less. Instead, locate units above less
sensitive noise areas such as above or in equipment
rooms, utility closets, restrooms, storage rooms, or
above corridors.
3. Provide at least 10 feet between WSHP units to avoid
the additive effect of two noise sources.
4. Provide an acoustical pad underneath the WSHP unit
in applications where the unit must be mounted
above noise sensitive areas such as private offices or
conference rooms. The pad attenuates radiated noise.
Be sure the pad has an area at least twice that of the
WSHP footprint.
5. Maximize the installed height above the suspended
ceiling.
6. Be sure the WSHP unit is located at least 6 feet away
from any ceiling return grille to prevent line-of-sight
casing noise to reach the space below.
7. Suspend horizontal WSHP unit from the ceiling with
hangers that use spring or neoprene type isolators to
reduce vibration transmission.
8. Use flexible electrical connections to the WSHP unit.
DO NOT USE RIGID CONNECTIONS.
9. Use flexible loop water and condensate piping con-
nections to the WSHP unit.
10. Use a canvas duct connector to connect the WSHP
discharge flange to the downstream duct system to
reduce vibration-induced noise.
11. Provide acoustic interior lining for the first 20 feet of
discharge duct, or until the first elbow is reached. The
elbow prevents line-of-site sound transmission in the
discharge duct.
12. Provide turning vanes in ductwork elbows and tees to
reduce air turbulence.
13. Size the sheet metal supply duct with velocities no
greater than 1000 fpm.
14. Ensure ductwork is rigid.
15. Use round ducts whenever possible to further reduce
noise.
16. Allow at least 3 equivalent duct diameters of straight
duct upstream and downstream of the unit before
allowing any fittings, transitions, etc.
17. Seal all penetrations around duct entering the space.
18. Provide a 4-ft run-out duct made of flexible material
to connect a diffuser to the supply trunk duct. The
flex duct provides an “attenuating end-effect” and
reduces duct-transmitted sound before it reaches the
space. Flex ductwork typically reduces sound by 6 dB.
19. Locate the run-out duct balancing damper as far away
from the outlet diffuser as possible. Locating the
balancing damper at the trunk duct exit is best.
20. If return air is drawn through a ceiling plenum, provide
an acoustically lined return duct elbow or “L” shaped
boot at the WSHP to eliminate line-of-sight noise into
the ceiling cavity and possibly through the ceiling
return air grilles. Face the elbow or boot away from
the nearest adjacent WSHP unit to prevent additive
noise.
21. Do not hang suspended ceiling from the ductwork.
Vertical units
All guidelines established for horizontal units also apply for
vertical units. In addition, since vertical units tend to be in-
stalled in small equipment rooms or closets, the following
additional guidelines apply:
1. Mount the unit on a pad made of high-density sound
absorbing material such as rubber or cork. Extend the
pad beyond the WSHP unit footprint by at least
6 inches in each direction.
2. Since the unit returns airflow through a grille
mounted in a closet door, provide a sound barrier or
some other modification of the closet to prevent line-
of-sight noise into the conditioned space.
3. Follow good duct design practice in sizing and locat-
ing the connection of the WSHP discharge to the
supply duct system. Use an elbow with turning vanes
bent in the direction of the fan rotation to minimize
turbulence. Make any duct transitions as smooth and
gradual as possible to further minimize turbulence and
loss of fan static pressure.
Solenoid valves
In applications using variable flow pumping, solenoid
valves can be field installed and operated from the control
board in the Aquazone™ WSHP unit.
Freeze protection
Applications where systems are exposed to outdoor
temperatures below freezing (32 F) must be protected from
freezing. The most common method of protecting water
systems from freezing is adding glycol concentrations into
the water. Use design care when selecting both the type
and concentrations of glycol due to the following:
• equipment and performance may suffer with high con-
centrations of glycol and other antifreeze solutions
• loss of piping pressure may increase greatly, resulting in
higher pumping costs
• higher viscosity of the mixture may cause excess corro-
sion and wear on the entire system
• acidity of the water may be greatly increased, promot-
ing corrosion
• glycol promotes galvanic corrosion in systems of dissim-
ilar metals. The result is corrosion of one metal by the
other, causing leaks.
