14
AGZ 026B through 130B
IOMM AGZ-5
Ambient and Water Flow Limitations
AGZ units are designed to operate in temperatures as show in the following table.
Table 5, Unit Maximum Operating Ambient Temperature
AGZ Unit Model
Standard
Controls
w/ Low Ambient
VFD Control Option
w/ or w/o Low Ambient VFD Control
Plus High Ambient Panel Option
AGZ 026B – 130B
115
°
F 105
°
F 125
°
F
The VFD Low Ambient Control Option on models AGZ 026B to 130B imposes an additional heat
load on the control panel limiting operation to 105
°
F ambient temperature. The addition of the
High Ambient Panel Option allows operation to 125
°
F ambient temperature.
Compressor loading and unloading is adaptively determined by system load, ambient air
temperature, and other inputs to the MicroTech II control algorithms. A low ambient fan VFD
option allows operation down to 0°F (-18°C). The minimum ambient temperature is based on still
conditions where the wind is not greater than five mph. Greater wind velocities will result in
reduced discharge pressure, increasing the minimum operating ambient temperature. Field installed
hail/wind guards are available to allow the chiller to operate effectively down to the ambient
temperature for which it was designed.
Evaporator flow rates below the minimum values can result in laminar flow causing freeze-up
problems, scaling and poor control. Flow rates above the maximum values will result in
unacceptable pressure drops and can cause excessive erosion, potentially leading to failure.
Water Piping
Local authorities can supply the installer with the proper building and safety codes required for safe
and proper installation.
Install piping with minimum bends and changes in elevation to minimize pressure drop. The following
issues must be considered when designing and installing water piping:
1. Vibration eliminators to reduce vibration and noise transmission to the building.
2. Shutoff valves are required to isolate the unit from the piping during unit servicing.
3. Manual or automatic air vent valves at the high points of the system. Drains must be installed at
the lowest points in the system.
4. Adequate water pressure must be maintained (expansion tank or regulating valve).
5. Temperature and pressure indicators located at the unit are required to aid in unit servicing.
6. A strainer or other means of removing foreign matter from the water before it enters the pump must
be installed. Place the strainer far enough upstream to prevent cavitation at the pump inlet (consult
pump manufacturer for recommendations). The use of a strainer will prolong pump life and keep
system performance up.
7. A strainer must be installed in the water line before the inlet of the evaporator. This will help
prevent foreign material from entering and decreasing the evaporator performance.
8. The unit’s evaporator has a thermostat and heater to prevent freeze-up down to -20
°
F (-29
°
C).
The heating cable can be wired to a separate 115V supply circuit. As shipped from the factory, the
heating cable is wired to the control circuit. All water piping to the unit must also be protected to
prevent freezing.
Summary of Contents for AGZ026BS
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Page 104: ...104 AGZ 026B through 130B IOMM AGZ 5...
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