W7459 Enthalpy Setpoint Chart - Honeywell Design and Application Technical Reference Manual

HIGH LIMIT
CURVE FOR
W7459 D,
W6210D AND
W7210D
30 BTU/LB
69.7 k-J/kg
25 BTU/LB
58 k-J/kg
20 BTU/LB
46.4 k-J/kg
15
BTU/LB
34.8 k-
J/kg
D
40 °F 50 °F
4 °C 10 °C
35 °F 45 °F
2 °C 7 °C
This is the psychrometric chart for the setpoint
on the W7459 enthalpy modules. It is similar
to the charts for the H705 except for the
enthalpy high limit line to the right of the A
curve. This is a specialized limit used only in
the W7459D, W6210D, W7210D and W7212
controllers. When the enthalpy of both the
return and outside air is to the right of the limit
line the outside air dampers are closed to the
minimum position and the mechanical cooling
is energized.

W7459 Enthalpy Setpoint Chart

50 BTU/LB
45 BTU/LB
104.5 k-J/kg
40 BTU/LB
92.8 k-J/kg
35 BTU/LB
81.4 k-J/kg
A
B
C
60 °F 70 °F
16 °C 21 °C
55 °F 65 °F
13 °C 18 °C
DRY BULB TEMPERATURES
116 k-J/kg
80 °F 90 °F
27 °C 32 °C
75 °F 85 °F
24 °C 29 °C
Control Curve
A
B
C
D
Knob turned
to D
When using differential enthalpy the outdoor
air is compared to the return air and you set
the potentiometer to "D" to prevent the return
air from being to the left of the enthalpy curve.
57
Section 6 - W7459 Economizer Module
100 °F 110 F
38 °C 43 °C
95 °F 105 °F 115 °F
35 °C 41 °C 46 °C
Control Point
(Approximate Temperature
at 50% Humidity)
73°F (23°C)
70°F (21°C)
67°F (19°C)
63°F (17°C)
For Differential Enthalpy
(2 Sensor)
Honeywell Economizers 63-8594-02
120 °F
49 °C
M25283A