each day of the week. The time program shall allow two separate
temperature setback intervals per day. Thermostats shall have a means for
temporary and manual override of program schedule, with automatic program
restoration on the following day. Thermostats shall have a replaceable
battery to maintain timing and to maintain the schedule in memory for one
year in the event of a power outage. Maximum differential shall be one
degree C 2 degrees F. Where used for heat pump applications, thermostat
shall have an emergency heat switch.
2.8.4
Nonmodulating Capillary Thermostats and Aquastats
a.
Thermostat shall have a capillary length of at least 1 1/2 meters
5 feet, adjustable direct reading scales for both setpoint and
differential, and a differential adjustable from 3 to 9 degrees C
6 to 16 degrees F.
b.
Aquastats shall be strap-on type, with 5.50 degrees C 10 degrees F
fixed differential.
2.8.5
Low-Temperature Protection Thermostats (Freezestats)
**************************************************************************
NOTE: Indicate capillary serpentined in a plane
perpendicular to airflow to uniformly sense entire
airflow.
**************************************************************************
Low-temperature protection thermostats shall be manually reset
low-temperature safety thermostats, with NO and NC contacts or a
two-position pneumatic output signal and a 6 meters 20 foot element which
shall respond to the coldest 456 mm 18 inch segment.
2.8.6
Modulating Capillary Thermostats
Thermostats shall have either one output signal, two output signals
operating in unison, or two output signals operating in sequence, as
required for the application. Thermostats shall have adjustable
throttling ranges of 2 to 4 degrees C 4 to 8 degrees F for each output.
2.8.7
Modulating Pneumatic Room Thermostats
Two-temperature combination thermostats shall be adjustable proportioning
type with dual setpoints containing two temperature sensing elements: one
for heating control and one for cooling control; two for heating control or
two for cooling control. Changeover for two-temperature combination
thermostats shall be accomplished by a change in control air supply
pressure which selects proper setpoint and proper controller action.
Single-temperature thermostats shall be adjustable proportioning type with
one temperature sensing element: one setpoint and proper controller action.
"Dead-band" thermostats shall have one adjustable proportioning type
controller with two setpoints, adjustable dead-band, and one controller
output or two adjustable proportioning type controllers mounted on a common
backplate with two setpoints, adjustable dead-band, and two controller
outputs. Temperature sensing elements shall be selected for proper
controller action. Individual temperature-sensing elements shall have a
separate adjustable throttling range of one to 5.50 degrees C 2 to 10
degrees F; thermostat shall have a minimum range of 13 to 32 degrees C 55
to 90 degrees F and minimum safe air input pressure of 172 kPa (gage) 25
psig. Dead-band setting shall have a minimum adjustable range of 2 to 8
SECTION 15901N
Page 28
Previous Page
