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required.
difference in number of diffuserers
needed for heating and cooling
There may be cases in which the number of
outlets needed for heating may be
significantly different than the amount needed
to meet the cooling load for the room. If this
happens, then you will have to take the
greater number of outlets to provide both
heating and cooling for the room. If there is a
large difference in the number of diffusers
required for heating and cooling, then vents
can be opened or closed to provide
summer/winter adjustment.
diffuser design notes
Unlike conventional systems it is not
necessary to locate MaxAir™ diffusers
above/below windows or to center diffusers
along an exterior wall length. Diffusers can be
located on interior walls if necessary but if
possible keep them closer to exterior walls for
maximum occupant comfort.
Air from the diffuser is introduced into the
room at a high velocity. This creates a venturi
effect at the diffuser. This negative pressure
draws room air into the conditioned air
stream and mixes and distributes both air
streams together. This phenomenon
constantly stirs the room air and prevents
stratification and stale air accumulation.
It is preferred to locate the diffusers in low
traffic areas of the room to be conditioning.
Diffusers should be located at least 8 inches
(to center of diffuser from finished surface)
from walls and should not be located near
curtains or wall coverings that will be affected
by the high velocity air stream. The diffusers
should not be located under furniture or near
obstructions that will nullify the mixing effect
that the diffusers are designed to accomplish.
In kitchens or bathrooms where it may not be
desirable to locate a diffuser on the floor the
diffusers can be located in a kick space or on
the wall and discharge the air horizontally. In
akickspacethediffusermayhavetobe
trimmed to fit properly. In the bathroom do
not locate in an area that will cause a draft on
people entering or leaving a bath or shower.
trunk duct design notes
The location of the main trunk duct will be
determined by the structural design of the
building. One of the main goals in laying out
the trunk duct is to achieve a self-balancing
system.
A common location for the horizontal trunk
duct is along the main structural support
beam, at the center of the building in the
basement, and at right angles to the floor
joists. This will yield the shortest and most
equidistant 2 ½” branch runs as possible.
Utilizing this layout will provide a self-
balancing system for the main floor and
basement.
A common location for the vertical trunk duct
on a two storey building is in a closet or
furred wall as close to the building center as
possible. This will allow the second floor
horizontal trunk duct, (located in the attic) run
at the building center line, to be divided 50/50,
front to back, with equidistant branch run
lengths, to again be self balancing for the
second floor. Where the MaxAir™fancoil
unit has two trunk ducts ensure the trunk
ducts are as close as possible in equivalent
length.
For trunk duct runs it is recommended that
the duct be insulated to prevent supply air
temperature losses/gains. Where the trunk
duct is run through unconditioned spaces the
duct must be insulated and provided with a
vapor barrier to meet the local code
requirements. In unheated attics the trunk
duct should be laid on the ceiling joists,
insulated and provided with vapor barrier,
then the attic insulation should be laid over
top of the duct to further reduce duct
losses/gains. In conditioned spaces and if the
trunk duct is less than 25% of the maximum
allowable trunk duct length (Table 2) the duct
