2.5.9
Fans
Provide belt-driven evaporator fans with adjustable pitch pulleys; except
for units less than 17 1/2 kW 5 ton capacity, direct drive with at least
two speed taps may be used. Select pulleys at approximately midpoint of
the adjustable range.
2.5.10
Filters
Provide filters of the type specified in this section.
2.5.11
Filter Boxes
Provide when filters are not included integral with air conditioning units.
Construct of not less than No. 20 US gage steel with track, hinged access
doors with latches, and gaskets between frame and filters. Arrange filters
to filter outside and return air. Provide removable filter assemblies,
replaceable without the use of tools.
2.5.12
Mixing Boxes
Provide of the physical size to match the basic unit and include equal
sized flanged openings, sized to individually handle full air flow. Arrange
openings as indicated. Provide openings with dampers of parallel or
opposed blade type. Provide opposed blade type for modulating dampers and
parallel type for two-position dampers. Connect damper shafts together by
one continuous linkage bar. Arrange dampers for [automatic] [or] [manual]
operation so that when one starts to close from its opened position, the
other starts to open from its closed position.
2.5.13
Thermostats
**************************************************************************
NOTE: Typical specifications for a simple system
with both single-stage cooling and single-stage
heating. Modify as required to suit the project.
**************************************************************************
Provide adjustable type that conforms to applicable requirements of UL 873.
Provide combination heating-cooling type with contacts hermetically sealed
against moisture, corrosion, lint, dust, and foreign material. Design to
operate on not more than 0.83 degrees C 1.5 degrees Fdifferential and of
suitable range calibrated in degrees C degrees F. Provide adjustable heat
anticipation and fixed cooling anticipation. Provide two independent
temperature sensing elements electrically connected to control the
compressor and heating equipment, respectively. Accomplish manual
switching for system changeover from heating to cooling or cooling to
heating and fan operation through the use of a thermostat subbase. Provide
system selector switches to provide "COOL" and "OFF" and "HEAT" and fan
selector switches to provide "AUTOMATIC" and "ON." Provide relays,
contactors, and transformers located in a panel or panels for replacement
and service.
2.5.13.1
Cooling
a.
When thermostat is in "COOL" position with fan selector switch in
"AUTO" position, compressor, evaporator fan, and condenser fan
shall cycle together.
SECTION 15730N
Page 20
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