H705 Wiring Diagram - Honeywell Design and Application Technical Reference Manual

TRANSFORMER
L1
(HOT)
L2
H705 ENTHALPY CONTROL
TR TR1
B C
S
O
A D
S
R
3
2 1
COOLING
COMMERCIAL THERMOSTAT
The H705 enthalpy control is being used in
this application in place of a dry bulb
temperature economizer high limit. The H705
included a single enthalpy sensor for the
outside air. An optional second C7400
installed in the return air was used for
differential enthalpy. If the second C7400
sensor is not used a 620 ohm resistor was

H705 Wiring Diagram

TR
TR1
+
620 OHM
RESISTOR
SR
1
2
ENTHALPY
DECREASE
3
RC
Y1
Y2
45
Section 4 - H705 Economizer Module
MIXED AIR
DAMPER MOTOR
T1
T2
W
W
1 0 0
8 0
R
1 2 0
6 0
4 0
1 4 0
° F
MINIMUM
POSITION
CONTROL
NC
NC
COOLING
CONTACTOR
installed across the S
economizer modulated the outdoor dampers
for free cooling provided the outside air
enthalpy was below the setpoint on the H705.
If the outdoor enthalpy is above the setpoint
the outside air dampers are closed to a
minimum position for ventilation and the
mechanical cooling is energized.
R B
W
120
F
110 130
100
140
90
15
R
80 16
70
170
60 180
B
T991 MIXED
AIR CONTROL
C
NO
RELAY
C
NO
T 1
L 1
T 2
L 2
M13818A
and + terminals. The
R
Honeywell Economizers 63-8594-02