Armstrong World Industries EHU-700 Series, EHU-703, EHU-701, EHU-704 manual Audible Alarm, Board

Figure 12-1
				24 VAC	Steam
			Drain Valve A		Generator A
				High Water
				Switch A
	24 VAC	Panel Switches
Low-Voltage	Fill Valve	Drain	Tank	Mode
		On/Off	On/Off	Select
Low-Energy
Controls
Main Control
Humidistat		Micro Controller
					Current
		Printed Circuit			Transformer
High Limit*
			Board
Humidistat
Air Flow*
Switch
					24 VAC
N.O. Alarm					Contactor
Relay		LED
				Three-Digit
		Display
*Must be closed to run				Numerical Display
	Side 1			Side 2
	24 V Secondary
	Power Transformer
					High Voltage
					Terminals

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