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Manual 2100-522B
Page 11 of 38
DUCT WORK
All duct work must be properly sized for the design
airflow requirement of the equipment. Air Conditioning
Contractors of America (ACCA) is an excellent guide to
proper sizing. All duct work or portions thereof not in
the conditioned space should be properly insulated in
order to both conserve energy and prevent condensation
or moisture damage. When duct runs through unheated
spaces, it should be insulated with a minimum of one
inch of insulation. Use insulation with a vapor barrier
on the outside of the insulation. Flexible joints should
be used to connect the duct work to the equipment in
order to keep the noise transmission to a minimum.
The Q-T
EC
series unit has provision to attach a supply
air duct to the top of the unit. Duct connection size is 12
inches x 20 inches. The duct work is field supplied and
must be attached in a manner to allow for ease of
removal when it becomes necessary to slide the unit out
from the wall for service. See Figure 7 for suggested
attachment method.
The Q-T
EC
series units are designed for use with free
return (non-ducted) and either free blow with the use of
QPB Plenum Box or a duct supply air system.
The QPB and QPBHW Plenum Box mounts on top of
the unit and has both vertically and horizontally
adjustable louvers on the front discharge grille.
For hot water coil option a QPBHWxx-F for free blow
or QPBHWxx-D for ducted airflow is used.
When used with a ducted supply, a QCX Cabinet
Extension can be used to conceal the duct work above
the unit to the ceiling. This extends 20" above the unit
for a total height above the floor of 10'-7/8". The unit is
equipped with a variable speed indoor blower motor
which increases in speed with an increase in duct static
pressure. The unit will therefore deliver proper rated
airflow up to the maximum ESP shown in Table 7.
However, for quiet operation of the air system, the duct
static should be kept as low as practical, within the
guidelines of good duct design.
FILTERS
Two 1-inch throw away filters [(1) 16x16 and (1)
16x20] are supplied with each unit. The filters slide into
filter brackets. Refer to Figure 8.
The filters are serviced from the inside of the building
by opening the hinged door. This door is attached by a
screw and one locking latch.
The internal filter brackets are adjustable to
accommodate 2-inch filters. The tabs for the 1-inch
filters must be bent down to allow the 2-inch filters to
slide in place.
NOTE: Unit cabinet, supply air duct and free blow
plenum are approved for “0” clearance to
combustible material.
FIGURE 7
SUPPLY DUCT CONNECTIONS
SUPPLY DUCT
TO BE FIELD
SUPPLIED
ATTACHMENT
SCREWS TO
BE FIELD
SUPPLIED
ROOM SIDE OF
Q-T
EC UNIT
DUCT FLANGE
PROVIDED WITH
UNIT
FIGURE 8
FILTER LOCATION
RETURN AIR
GRILLE
FILTERS