23 © STULZ GmbH – all rights reserved EN/01.2019/G22
EC TOWER TECHNICAL MANUAL
Design conditions for technical data
Electrical connection data: 400 V/3 Ph/50 Hz
Ext. static pressure of Downflow units: 20 Pa
Ext. static pressure of Upflow units: 50 Pa
Return air conditions for heat exchanger output: +24 °C, 50 % RH
Outside temperature for heat exchanger output: –15 °C to +35 °C
- with 7 m refrigerant pipe
The noise level figures apply at a height of 1 m and a distance of 1 m in front of the unit, in free-field conditions
and with nominal data. These figures take into consideration the influences of all integral and design parts in
the standard unit. In Upflow units, the figures apply with a blow-out duct connected.
Cooling mode at low ambient temperatures
IMPORTANT:
At low ambient temperatures, FDS outdoor units can run in cooling mode within the temperature ranges spec-
ified above. At extremely low temperatures, take the following precautionary measures. Otherwise, the unit
cannot be operated even if the temperature range is within the above-mentioned operating limits, and the
cooling capacity cannot be used under certain conditions.
Precautionary measures
At extremely low temperatures:
1) Locate the outdoor unit so that strong wind does not blow directly into it.
2) If a suitable installation location is not available, install the flexible airflow adapter or similar device on the
outdoor unit, to deflect a strong wind and prevent it from blowing into the outdoor unit.
Explanation
At a low ambient temperature of –5 °C or less, the fan controller sets the fan of the outdoor unit to low or low-
est speed. However, if a strong wind blows directly into the outdoor unit, the temperature of the unit’s heat
exchanger drops even further. This results in a pressure drop in the upper and lower ranges. This drop in low
pressure causes the temperature of the heat exchanger in the indoor unit to fall, activating the frost protection
control in this heat exchanger at short intervals. This makes cooling mode impossible.
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