2.2.6.2
Air Quality Sensor
Provide full spectrum air quality sensors with filters utilizing hot wire
element based on the Taguchi principle. The sensor monitors a wide range of
gaseous organic materials which are common components of indoor air
contaminants. These gaseous materials include paints and solvents, cooking
and cigarette smoke, and car exhaust. The Sensor must compensate for
temperature and humidity, have span and calibration potentiometers, operate
on 24 VDC power with output of 0-10 VDC and operating between 32 to 140
degrees F and 5 to 95 percent RH. Provide isolation power supply for each
sensor.
2.2.7
Input Switches
2.2.7.1
Timed Local Override
Provide momentary contact push button override with override time set in
controller software. Provide to override DDC time of day program and
activate occupancy program for assigned units. Upon expiration of override
time, the control system shall return to time-of-day program. Time
interval for the length of operation shall be software adjustable and shall
expire unless reset.
2.2.7.2
Hand-Off-Auto Switch
Provide hand-off-auto switch with name plate to manually switch between
off, DDC (auto) and manual (hand) control. Size and wire hand-off-auto
switch to switch control (120 VAC or less), not line, circuitry. Wire all
safety controls to protect circuit and equipment during both hand and auto
operation.
2.2.7.3
Insertion Freeze Protection Switch
Electric switch shall be capillary type. Provide special purpose insertion
thermostats with flexible elements a minimum of 20 feet in length for coil
face areas up to 40 square feet. Switch contacts shall be rated for motor
starter circuit voltage being interrupted. Switch shall be equipped with
auxiliary set of contacts for input of switch status to digital controller.
Provide additional elements or longer elements for larger coils at the
rate of 1-foot of element per 4 square feet of coil. Serpentine
capillaries perpendicular to the air flow to uniformly sense the entire
airflow. A freezing condition at 18-inch increments along the sensing
element shall activate the thermostatic switch. Switch shall require
manual reset after activation.
2.2.7.4
Non-Modulating, Electric, Humidistat Switch
Provide a set point adjustable, wall mounted humidistat. Contacts shall be
Single Pole Double Throw(SPDT) for low voltage (24volt) applications.
Adjustable set-point range shall be 20%-80% relative humidity. Sensing
element shall be bulk polymer or thin film polymer with an accuracy of plus
or minus 2 percent over the entire range. Sensing element shall be
non-saturating and shall be capable of withstanding a saturated condition
without permanently affecting calibration or sustaining damage.
Humidistat cover shall consist of locking metal or heavy-duty plastic.
SECTION 15910N
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