8
OPTIONS
WATERSIDE ECONOMISER
A waterside economizer can be used where the unit’s entering water temperature is between 45 and
55° F. The economizer coil will act as the first stage of cooling if the water is cold enough. If the
economizer is unable to maintain the zone or supply air temperature set point, one stage of DX
cooling will also come on to meet the required set point. (Refer to sequence of operation for more
details) The waterside economizer is internal to the unit. All economizer control valves, piping
between the economizer and the condensers, and all the wiring is factory installed. All piping and
control valves are located within the unit enclosure.
The waterside economizer will take advantage of cooling tower water to pre-cool the entering air to
aid in mechanical cooling process, or if the water temperature is low enough, the waterside
economizer will provide total cooling.
3-WAY DIVERTING VALVE (ECONOMIZER VALVE)
The 3-way diverting valve is used when a unit is equipped with a waterside economizer coil. The
threaded ball valve is designed to provide 2-position control of hot or cold water systems. This
valve comes combined with an electronic actuator that stops automatically when the motor reaches
its end position. The actuator is mounted directly to the valve-operating shaft with a universal v-
bolt clamp assembly. Control of the valve is on/off. The direction of the rotation is reversible. The
3-way diverting valve diverts water directly to the economizer coil upon a signal from the entering
water thermostat. The water then goes to the condensers and out the unit. If the economizer
function is not enabled the 3-way diverting valve will then direct the water directly to the
condensers.
ECONOMIZER CONTROL
The economizer mode is activated when water temperature is lower than water set point and that
the discharge air is under the 68°F set point on economizer mode (adjustable).
