SKE Humidifier
User Manual
20
8.3.
Common Alarm Connections
A volt free contact is provided in the form of both a normally open and normally closed contact that will
switch in the event of an alarm on the SKE humidifier.
Wherever possible it is recommended to
use the normally closed contact. This
contact will open in the event of a
humidifier fault.
These contacts should be used to switch a
low voltage, ideally
24V
, with a switching
current of no more than
3 Amps
.
1
8
7
5
4
3
2
F
6
9
Common
Normally Open
Normally Closed
(Illus. 49)
8.4.
Controls Placement (steam dispersed into a duct or AHU)
Typical humidifier control system should include along with the humidifier:
A wall or return duct humidistat
A high limit duct humidistat,
An air proving switch.
Placement of these devices is critical to proper operation of the overall system.
The return duct humidistat must always be located before any outside air intake, in order to
ensure accurate sensing of the air from the humidified space.
Alternatively a room humidistat can be used. The room humidistat should be located on an inside
wall or column. It should not be be near any discharge air from supply ducts or sources of heat or
cold.
The airflow switch must be positioned to accurately open on a loss of air flow, to prevent the
humidifier from running when there is no air to absorb humidity.
The high limit humidistat must be positioned far enough - 1.8m minimum - downstream of the
steam dispersion manifold(s) to prevent it from getting wet, but still allows it to accurately prevent
overhumidification of the duct that could result in condensation.
Return SHC80
Humidity sensor
ai
r
ai
r
air
air
Or room HRO20
humidistat
High limit humidistat
High limit SHC80 for
VAV application only
6' minimum
(1.8m)
Air flow switch
Steam dispersion
manifold
(Illus. 50)
