Operating instructions
IMM AGSB-60 7
Restricted Airflow
General
The clearances required for design operation of AGS air-cooled condensers are described in
the previous section. Occasionally, these clearances cannot be maintained due to site
restrictions such as units being too close together or a fence or wall restricting airflow, or both.
The McQuay AGS chillers have several features that can mitigate the problems attributable to
restricted airflow.
• The “W” shape of the condenser section allows inlet air for these coils to come in from
both sides and the bottom. All the coils in one "W" section serve one compressor. Every
compressor always has its own independent refrigerant circuit.
• The MicroTech II™ control is proactive in response to off-design conditions. In the case
of single or compounded influences restricting airflow to the unit, the microprocessor will
act to keep the compressor(s) running (at reduced capacity) as long as possible, rather than
allowing a shut-off on high discharge pressure.
Figure 3, Coil and Fan Arrangement
The following sections discuss the most common situations of condenser air restriction and
give capacity and power adjustment factors for each. Note that in unusually severe conditions,
the MicroTech II controller would adjust the unit operation to remain online until a less severe
condition is reached.