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## 11.1.3 Cooling requirements 

The z15 cooling system includes with two options: Radiator (air) cooled or water-cooled system. Single chip modules (SCMs) are always cooled with an internal water loop, no matter which z15 cooling option is chosen. The liquid in the internal water circuit can be cooled by using a radiator (for air-cooling option) or customer-supplied chilled water supply (for water-cooling option). I/O drawers, PCIe I/O drawers, power enclosures, and CPC drawers are cooled by chilled air with blowers. 

The z15 servers include a recommended (long-term) ambient temperature range of 18°C (64.4°F) - 27°C (80.6°F). The minimum allowed ambient temperature is 5°C (41°F) and the maximum allowed temperature is 40°C (104°F). 

For more information about cooling requirements, see IBM Z 8561 Installation Manual for Physical Planning , GC28-7002. 

## Radiator (air) cooling 

The following radiator (air) cooling options are available: 

GLYPH<SM590000> A-Frame radiator air-cooled feature code (FC 4033) 

GLYPH<SM590000> B-Frame radiator air-cooled feature code (FC 4035) 

The radiator cooling system requires chilled air to fulfill the air-cooling requirements. z15 system airflow is from the front (intake, chilled air) to the rear (exhausts, warm air) of the frames. The chilled air is provided through perforated floor panels in front of the system 

The hot and cold airflow and the arrangement of server aisles are shown in Figure 11-3. 

<img src='content_image/982790.jpg'>

As shown in Figure 11-3, rows of servers must be placed front-to-front. Chilled air is provided through perforated floor panels that are placed in rows between the fronts of servers (the cold aisles). Perforated tiles generally are not placed in the hot aisles. If your computer room causes the temperature in the hot aisles to exceed a comfortable temperature, add as many perforated tiles as necessary to create a satisfactory comfort level. Heated exhaust air exits the computer room above the computing equipment. 

