Airedale Ultima Compact FreeCool 30kW - 450kW - Manual (Page 13)

Chillers ULTIMA COMPACT FREECOOL
Chillers
13
Technical Manual : 6259576 V1.2.0_02__2013
Design Features & Information
CAUTION All free cooling units should use minimum 20% glycol concentration.
FREE COOLING The Ultima Compact FreeCool chiller has been designed to provide the cooling load
required whilst optimising energy efficiency at all times and as such will take advantage
of free cooling whenever available. If the free cooling available cannot satisfy the required
full cooling load, direct expansion cooling is used to supplement the output as
shown below:
1 2
1 Water Inlet
2 Water Outlet
FREE COOLING
OPERATION In high ambients where free cooling is not available the fan speed modulates in the
conventional manner to maintain a constant head pressure. Free cooling is initiated
wherever the outdoor ambient is 1°C less than the return water temperature.
When free cooling and DX mechanical cooling are operating simultaneously the
condenser fan speed will operate at 100% maximising free cooling.
In ambients where the free cooling coil is capable of satisfying the full cooling demand,
the condenser fans are modulated to provide the desired duty. The condenser fans are
capable of being modulated between 25-100% of airflow to maintain the supply
water temperature.
During periods where the condenser fan speed has been reduced to a minimum, the
supply water temperature will then be controlled by the 3 way valve.