Nortec NHTC - Manual (Page 61)

10-10
Page 53
2008-10-01
7. CONTROLS
A. GENERAL
(1) NORTEC humidifiers all accept on/off controls for their security loop. Many NORTEC
humidifiers can also accept modulating or transducer signals for control (See the
features section for each specific model).
CAUTION
REGARDLESS OF SELECTING ON/OFF OR MODULATING CONTROL
METHOD, NORTEC HUMIDIFIERS MUST HAVE CLOSED CIRCUIT
ACROSS ITS ON/OFF SECURITY LOOP CONTROL TERMINAL TO
OPERATE. NORTEC HIGHLY RECOMMENDS THE USE OF A HIGH
LIMIT HUMIDISTAT AND AN AIR PROVING SWITCH IN SERIES FOR
THIS FUNCTION.
B. ON/OFF CONTROLS
(1) On/Off controls are used in all NORTEC humidifier security loops. The digital
humidistat can also be used as a space humidity controller. These controls include:
(a) Air Proving Switch – duct mounted, pressure differential switch, adjustable set
point from 0.07 IWC to 12.0 IWC, good for positive, negative or differential
pressure applications, stops humidifier if duct air pressure is not sensed. Turns
humidifier off if air handler fails.
(b) Duct Mounted Digital Humidistat – control or high limit, adjustable set point from
15-90% rh with accuracy fixed at
±3% at 25°C
,
operating range of 0-95% rh, closes
on humidity drop for control and opens on rise for high limit duct application.
(c) Wall Mounted Digital Humidistat – control or high limit, adjustable set point from
15-90% rh with accuracy fixed at
±3% at 25°C
, operating range of 0-95% rh, closes
on humidity drop for control and opens on rise for high limit application.
(d) On/Off Controls Supplied by Others – Can be used as long as they have a dry set
of contacts capable of passing a 24-VAC, 2-A maximum signal.
C. MODULATING CONTROLS
(1) Modulating Controls are used to send a modulating demand signal to the NORTEC
humidifier. Different models can accept different signals (see features section for each
specific model) NORTEC supplied controllers send a 0-10 VDC demand signal. This
signal can be used as a control and in some models can also be used as a modulating
high limit. These controls include:
(a) Wall Mounted Digital Humidistat with Integrated Sensor – control or high limit,
adjustable set point from 15-90% rh with accuracy fixed at
±3% at 25°C, outputs a
0-10 VDC signal.
(b) Wall Mounted Digital Humidistat Without Sensor – control or high limit, adjustable
set point from 15-90% rh with accuracy fixed at
±3% at 25°C, outputs a 0-10 VDC
signal. Requires a remote transducer sensor supplying a 2-10 VDC signal.
(c) Duct Mounted Digital Humidistat With Sensor – This package comes with both a
remote sensor and a wall mounted controller without sensor. Control or high limit,
adjustable set point from 15-90% rh with accuracy fixed at
±3% at 25°C, outputs a
0-10 VDC signal.