Stulz CeilAir CW - Flooded Head Pressure Control (Condenser Model HES-CAA, -30 °F); Head Pressure Controls (Water- or Glycol-Cooled Systems); Humidifier Adjustment; Pressure Valves Rated 150 Psig (1.03 Mpa)

59OCH0006F08/13/2024
CEILAIR
®
CW & DX IOM
2.10.4 HUMIDIFIER ADJUSTMENT
When using this method of head pressure regulation there must be enough refrigerant in the system to
ensure adequate charge at the lowest expected ambient temperature in which the system will be operating. A
receiver is used to store the extra refrigerant when the condenser is not using it.
NOTE Max. Pressure Drop
Systems utilizing air cooled condensers must not have a refrigerant line pressure drop greater than 14
psig across the condenser and the interconnecting piping to the condenser sections.
2.10.2.6 Flooded Head Pressure Control (Condenser Model HESCAA, -30 °F)
Used for indoor installations where ambient condenser air inlet temperatures may fall to -30 °F. First,
familiarize yourself with Flooded Head Pressure Control in section 2.10.2.5. Instead of cycling the fan on
and off, the condenser fan speed is continuous. The head pressure control valve diverts discharge gas to the
receiver causing liquid to back up in the condenser, as described in section 2.10.2.5, while the fan continues
to run.
2.10.3 Head Pressure Controls (Water- or Glycol-Cooled Systems)
In a water- or glycol-cooled condenser, condensing temperature is maintained by the liquid flowing through a
regulating valve then into a liquid-cooled condenser. The regulating valve opens to increase the liquid flow as
the refrigerant pressure rises and closes as the refrigerant pressure falls. The regulating valve is factory set
for the correct condensing temperature; however, it can be adjusted to increase or decrease the condensing
temperature.
Head pressure regulating valves are available in two- or three-way configurations. Refer to the piping
diagram to determine which type of valve is provided. The location and size of regulating valves varies with the
size and model of the A/C unit. Methods for adjusting the valves for condensing pressure differ with the valve
types, which can be differentiated by the maximum water pressure rating of the valve: 150, 350, or 450 psig
(1.03, 2.41, or 3.10 MPa).
2.10.3.1 Pressure Valves Rated 150 psig (1.03 MPa)
Adjustment is made by turning the slotted square stem on top of the valve clockwise to increase the
condensing temperature or decrease water/glycol flow or turning counterclockwise to decrease the
condensing temperature or increase the water/glycol flow. A directional arrow is stamped on the metal
housing of the valve stem.
2.10.3.2 Pressure Valves Rated 350 psig and 450 psig (2.41 and 3.10 MPa)
Adjustment is made by turning the round-holed knob counterclockwise inside the valve’s metal housing to
increase condensing pressure or decrease water/glycol flow and clockwise to decrease the condensing
temperature or increase the water/glycol flow. A directional arrow is stamped on the metal housing of the
valve stem.
2.10.4 Humidifier Adjustment
The humidifier has a capacity adjustment potentiometer on the humidifier control circuit board. The capacity
potentiometer may need to be field adjusted if the humidifier does not supply enough capacity for the current
room conditions.