Trane HUV Installation Operation & Maintenance page 129

excessive temperatures are
sensed anywhere along the
leaving side of the coil. A
contactor shall also be included as
standard to ensure positive
disconnect of electric power
whenever fan motor power is
interrupted. A dead front switch
shall also be provided by the
manufacturer to disconnect power
when the access panel is opened.
All electric units shall have a
power wiring console in the right
hand end pocket to facilitate field
wiring of the unit.
Refrigerant Coils
Direct expansion coils shall con-
tain copper tubes mechanically ex-
panded into evenly spaced
aluminum fins. All coils are to be
proof and leak tested. The proof
test must be performed at 1.5
times the maximum operating
pressure and the leak test at the
maximum operating pressure. In
addition, the tubes are to be com-
pletely evacuated of air to check
for leaks in a vacuum.
The refrigerant coil distributor as-
semblies shall be Venturi or orifice
style with round copper distributor
tubes. Distributors shall be sized
consistently with capacity of coil.
Suction headers shall be fabricat-
ed from round copper pipe.
A thermostatic expansion valve
(TXV) shall be factory selected and
installed for a wide range of con-
trol to maintain optimum control
of superheat.
Refrigerant access ports shall be
factory supplied on high and low
side for easy refrigerant pressure
or temperature testing.
Steam Heating Coils
The steam coil shall be a 5/8-inch
design sigma-flow, tube-in-tube
distributing coil. All steam coil
copper tubing shall be mechani-
cally expanded into evenly spaced
UV-PRC001-EN
Mechanical
Specifications
aluminum fins. The supply and re-
turn connections shall be on the
same side with a 1-inch female
pipe thread (FPT) termination. The
coil shall be pitched to provide
condensate drainage for freeze
protection.
Fresh Air / Return Air Dampers
The classroom unit ventilator shall
be equipped with a dual blade
mixing damper with a compress-
ible seal to ensure proper modula-
tion and mixing of the return and
outdoor air. The damper shall be
capable of varying proportion of
mixed air from 100 percent room
air to 100 percent outside air. On
floor mounted units, an ultra low
leak damper seal made of closed
cell EPDM material shall be provid-
ed. Leakage shall be less than 1
percent against 0.5 inches external
static pressure.
Damper shall contain a continuous
divider placed between the damp-
er blades to separate the fresh air
and return air compartments to
prevent blow-through.
Bypass Damper
The face and bypass damper shall
be of aluminum and insulated for
sound attenuation to prevent for-
mation of condensate. Dampers
shall be tightly sealed and de-
signed to minimize heat pickup in
bypass.
Field Installed Controls
Classroom unit ventilators that
contain field installed controls
shall be operated with automatic
controls provided by the control
contractor and installed in the
field.
Pneumatic Controls
The pneumatic package shall in-
corporate a heat/cool changeover
mode for 4-pipe and 2-pipe heat/
cool options. The pneumatic con-
troller shall be factory furnished
and mounted for operation of the
classroom unit ventilator. The unit
shall be U.L. listed. The following
options shall be provided to work
with the pneumatic controller.
• Valve control
• Face and bypass control
• Night setback
• Morning warm-up
• Low limit thermostat
Direct Digital Controls
Factory mounted direct digital
controls shall contain a Comm 4 or
a Comm 5 communication proto-
cal. Both communication proto-
cals shall be capable of combining
HVAC and building management
into one comfort system. The di-
rect digital controls shall be facto-
ry commissioned to include
wiring, configuration and testing
for the system selected. The unit
shall be ready for hook-up to a
building automation system at
hardware set-up. The following
options shall be selectable with
DDC controls:
• Valve control
• Face and bypass control
• Economizer
• Dehumidification
• Water temperature sensor
• Night setback
• Morning warm-up
• Low limit thermostat
• Mixed air and discharge sens-
ing
• Fan, filter status switch
• Timed override
TM
• Integrated Comfort
capabilities
system
129