39
Installation
Nortec EL
2582302_C_EN_1611
5.7
Humidity Control Systems
5.7.1 Control Device Locations
The following schematic describes a potential system setup with respect to control devices. Refer to
Figure 23
.
Figure 23:
φ
φ
max
φ
Δp
1
1
2
3
System Setup Schematic
1 On/Off humidistat, modulating humidistat, or humidity sensor
2 On/Off high limit humidistat, modulating humidistat, or humidity sensor
3 Air proving switch
Notes:
•
Humidity sensors and humidistats (1) can be modulating or On/Off. Preferred location is in the return
duct, as the supply air is well mixed with the room air at this location. Avoid placing near discharge
diffuser, near doorways, in sunlight, or in airflow “dead-zones”.
•
Locate the high limit humidistat or humidity sensor (2) downstream of the humidifier’s distributor so that
it can sense a duct that is over-humidified. Recommended setting is 85% RH. Locate it downstream
of the distributor – at least 5x the absorption distance away. If the absorption distance is not known,
locate it at least 10 feet (3 m) downstream from the distributor. Can be a humidistat (modulating or
On/Off), or a humidity sensor.
•
Locate the air proving switch (3) in the same duct as the humidifier’s distributor so that it can sense
air flow (or lack thereof).
5.7.2 Permissible Control Signal Inputs
Table 8
shows the different permissible control signal inputs the Nortec EL steam humidifier can handle.
Table 8: Permissible Control Signal Inputs
Humidity Control with External Con
-
troller Control Signals
Humidity Control with Internal PI
Controller Humidity Sensor Signals
Digital Inputs (via Modbus,
BACnet IP/MSTP slave)
0-5 VDC (potentiometer 135-10kΩ)
1-5 VDC
0-10 VDC
2-10 VDC
0-20 VDC
0-16 VDC
3.2-16 VDC
0-20 mA
4-20 mA
0-5 VDC (potentiometer 135-10kΩ)
1-5 VDC
0-10 VDC
2-10 VDC
0-20 VDC
0-16 VDC
3.2-16 VDC
0-20 mA
4-20 mA
Standard
BACnet IP, BACnet MSTP (slave),
Modbus
Optional
BACnet IP (BTL), BACnet MSTP (Mas
-
ter, BTL), Lonworks
Humidistat (24 V On/Off)