Armstrong World Industries EHU-703 - Manual (Page 12)

12) AUDIBLE ALARM
There is an external alarm circuit provided. When an alarm condition is detected in the diagnostic
routines, a relay contact closes allowing activation of an external Class II device connected
between terminals 27 & 28. This circuit is rated to 1 amp.
12
Main Control
Humidistat
High Limit*
Humidistat
Air Flow*
Switch
*Must be closed to run
Micro Controller
Printed Circuit
Board
N.O. Alarm
Relay
24 V Secondary
Power Transformer
Side 1 Side 2
24 VAC
Drain Valve A
High Water
Switch A
24 VAC
Fill Valve
Current
Transformer
Steam
Generator A
24 VAC
Contactor
High Voltage
Terminals
LED
Display
Three-Digit
Numerical Display
Panel Switches
Drain
On/Off
Tank
On/Off
Mode
Select Low-Voltage
Low-Energy
Controls
Figure 12-1