Honeywell Design and Application User Manual

Section 4 - H705 Economizer Module
43 Honeywell Economizers 63-8594-02
H705 Components
The H705A Enthalpy Controller base
configuration was single sensor enthalpy
controller but could be used for differential
enthalpy. It was constructed of two devices: a
solid state C7400 enthalpy sensor on one side
of a metal plate and an enthalpy control on the
other side. The device was located in the
outside air stream with a recommended
minimum velocity of 500 feet per minute (152
meters per minute). The setpoint scale is A, B,
C and D. Each setting corresponds to an
enthalpy curve with A equalling the highest
enthalpy changeover and D being the lowest
enthalpy changeover. The output of this
control was an SPDT relay output used to
switch the mixed air dampers from return to
outside air and back as required for maximum
efficiency.
M23915A
3
1
TR1TR
A
D
O
S
R
S
C
B
2
ENTHALPY
SETPOINT
WIRES TO C7400
ENTHALPY SENSOR
ON THE BACK OF
PLATE
C7400 ENTHALPY
SENSOR ON
BACK OF PLATE
ENTHALPY
CONTROLLER ON
FRONT OF PLATE
ENTHALPY
CONTROLLER
RESISTOR THAT IS
REMOVED IF SECOND
ENTHALPY SENSOR
IS INSTALLED

Honeywell Design and Application Specifications

General

Brand	Honeywell
Model	Design and Application
Category	Controller
Language	English