32
Some of the factors that affect conversion of sound
power to sound pressure and consequent NC level include:
• Type of acoustical ceiling
• Use of metal or flex duct
• Absorption in the occupied space
• Location in the occupied space
• Open or closed layout plan
• Use of open or ducted returns
• Orientation of unit to occupant
• Use of lined or unlined duct
OCTAVE BAND SOUND PRESSURE LEVEL (Lp)
ASSOCIATED WITH NC CURVES
WSHP sound control
Analyzing the projected sound level in the conditioned
space caused by a WSHP unit is quite involved. The key is
to have good sound power ratings (Lw) in dB on the equip-
ment to determine the ductwork, ceiling and room sound
attenuation effect.
Console units
With console units, the fan and compressor are located
within the space, and only the casing design attenuates the
transmission of sound sources into the space. The designer
should carefully review the manufacturer’s acoustical data
when selecting console units and use lower fan speeds to
minimize space noise.
Operating limits
Environment
This equipment is designed for indoor installation ONLY.
Power supply
A voltage variation of ± 10% of nameplate utilization volt-
age is acceptable.
Starting conditions
The 50PEC unit will start and operate in an ambient tem-
perature of 50 F, with entering-air temperature at 50 F,
with entering-water temperature at 60 F, with both air and
water at the flow rates used in the ARI/ISO Standard
13256-1 rating test, for initial start-up in winter.
NOTE: These are not normal or continuous operating
conditions. Such a start-up should be used to bring the
building space up to occupancy temperature.
AIR LIMITS
WATER LIMITS
LEGEND
*Requires optional extended range insulation package when operating
below the dew point.
NOTES:
1. Minimum air and water conditions can only be used at ARI/ISO
13256-1 flow rates.
2. The 50PEC units may have up two values at maximum or mini-
mum with all other parameters at normal conditions.
Solenoid valves
In applications using variable flow pumping, solenoid
valves can be factory installed and operated from the con-
trol 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 mixture viscosity may cause excess corrosion
and wear on the entire system
• The water’s acidity may be greatly increased, promoting
corrosion
Glycol promotes galvanic corrosion in systems of dissimilar
metals. The result is corrosion of one metal by the other,
causing leaks.
NOISE
CRITERIA
CURVES
OCTAVE BAND SOUND PRESSURE LEVEL (Lp)
Frequency (Hz)
63 125 250 500 1000 2000 4000 8000
NC-15 49 36 26 17 17 14 12 11
NC-20 52 41 33 27 22 19 17 16
NC-25 54 45 38 31 27 24 22 21
NC-30 58 49 41 36 31 29 28 27
NC-35 61 53 45 40 36 34 33 32
NC-40 64 57 50 45 41 39 38 37
NC-45 67 61 54 49 46 44 43 42
NC-50 71 64 58 54 51 49 48 47
NC-55 74 68 63 58 56 54 53 52
NC-60 77 71 67 63 61 59 58 57
NC-65 80 75 71 68 66 64 63 62
50PEC UNIT
Cooling Heating
Min. Ambient Air 50 F 50 F
Rated Ambient Air 80 F 68 F
Max. Ambient Air 100 F 85 F
Min. Entering Air 50 F 50 F
Rated Entering Air, db/wb 80/66 F 68 F
Max. Entering Air, db/wb 100/82 F 80 F
50PEC UNIT
Cooling Heating
Min. Entering Water 30 F* 20 F*
Normal Entering Water 85 F 70 F
Max. Entering Water 120 F 90 F
db — Dry Bulb
wb — Wet Bulb
Application data (cont)
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