Nortec MH Series - Manual (Page 30)

27 | Installation
External Controls
Control Wiring
Humidity controls are available from Nortec as accessories. When the MH is used for cooling,
then controls must be supplied by others. If controls were not ordered with MH they must be
supplied by others. The following information is relevant to all controls, factory supplied or
otherwise. For wiring use minimum of 18 AWG and keep as short as possible.
The MHTC Reflow and Flow models can be operated with one modulating input for output
control or they can operate as On/Off. The MHB operates as a Modulating or On/Off unit.
See Controls on page 52 for MHTC control configuration.
Control Location
Figure 25: Control Location
1 Air Proving Switch
 Locate so that it can sense air flow or lack thereof.
2 Humidity / Temperature Control
 MHTC can be modulating, On/Off, or a humidity sensor. MHB can be modulating or On/Off.
 Can be located either in return air duct (preferred) or in room being humidified / cooled.
 Mount in area representative of room humidity / temperature (draft, doorways, sunlight, or
overhang such as a shelf can affect reading). Avoid placing near discharge diffuser of
humidified / cooled air.
Note:
Regardless of selecting on/off or modulating control method, The MH must have a
closed circuit across its on/off security loop control terminal to operate. Nortec highly
recommends the use of an air proving switch for this function.
Caution:
Failure to wire the MH in accordance with the wiring instructions could cause
permanent damage. Such errors will void the warranty.
1
2
Humidity/
temperature
control
(return air
duct or
in room)
Air
Proving
Switch