2.3.3.4
Outdoor Reset Thermostat
Thermostat shall be of the adjustable type set for a design temperature of
[_____] degrees C degrees F with a heating supply water temperature of
[_____] degrees C degrees F. A suitable ventilated weather shelter shall
be provided for the outside sensing element. Unit shall be mounted indoors
with its sensing element located in the outside air. Unit shall
proportionally reset the control point of a remote sensing temperature
controller.
2.3.3.5
Seven-Day Program Timer
Timer shall be provided with the proper switching action so that one timer
will switch all zones. Timer schedule for each zone shall raise and lower
the temperature twice during each 24-hour period throughout the week.
During the weekend, there shall be one cycle of raising and lowering the
zone temperature.
2.3.4
Control Valves and Controllers
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NOTE: Use the thermostatic steam regulating valve
for constant temperature applications such as
domestic hot water. Use steam pressure reducing
valves where reduced constant downstream pressure is
required. A central steam plant often requires this
type of valve to reduce pressure prior to the
distribution system.
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2.3.4.1
Thermostatic Steam Regulating Valve
Valve shall be adjustable; shall have an operating range of approximately
38 to 95 degrees C 100 to 200 degrees F and shall be furnished with a
thermostatic element, steam valve, connecting capillary tubing, and all
required accessories. Thermostatic element shall be inserted in a
separable socket in the hot-water supply main. Parts subject to wear shall
be constructed of noncorrodible metal and shall be easily replaceable.
2.3.4.2
Pressure-Reducing Valves
Valves designed for a working pressure of not less than 860 kPa 125 psig
shall be provided where indicated or otherwise required. Each reducing
valve shall be adjusted to maintain the desired terminal pressure within 20
kPa 3 psi, regardless of fluctuations in the initial pressure. Valves
shall be quiet in operation. Reducing valves provided in lines for space
heating only shall be of the double disk and seat type or sliding gate and
plate type. Reducing valves for dead-end service shall be single-seated or
sliding gate and plate type. Parts subject to wear shall be constructed of
noncorrodible metal and shall be easily replaceable.
2.3.4.3
General Purpose Control Valves and Controllers
Control valves and controllers shall as specified in Section 15951 DIRECT
DIGITAL CONTROL FOR HVAC AND OTHER LOCAL BUILDING SYSTEMS.
SECTION 15562A
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