SECTION 17: D
UCT
C
ONSIDERATIONS
75 of 198
SECTION 17: DUCT CONSIDERATIONS
The air handler has
b
een designed to operate at the
specific air
v
ol
u
me and external static press
u
re that
w
as ordered. This static press
u
re is generated
b
y any
additional components that are added to the heater
(i.e. inlet hood, filter section, dampers, d
u
ct
w
ork,
discharge heads, etc). Additional static press
u
re
b
eyond that ordered
w
ill affect the performance of the
air handler and lessen the air
v
ol
u
me that can
b
e
deli
v
ered.
See Page 75, Table 32
for static press
u
re
drop of air handler components.
Table 32: Internal Static Pressures (ISP)
Proper engineering methods need to
b
e employed
w
hen calc
u
lating d
u
ct and component static press
u
re
(i.e. 2009 ASHRAE Hand
b
ook - F
u
ndamentals,
Chapter 21).
The system d
u
ct
w
ork m
u
st comply
w
ith Sheet Metal
and Air Conditioning Contractors Nationals
Association (SMACNA) or any other recognized
standards.
As a general r
u
le, all discharge d
u
cts sho
u
ld ha
v
e a
straight r
u
n of at least 3 hydra
u
lic d
u
ct diameters
after the air handler
b
efore adding any fittings,
el
b
o
w
s, restrictions, etc. Ret
u
rn d
u
cts sho
u
ld ha
v
e
the same straight r
u
n
b
efore attaching to the
u
nit.
Hydra
u
lic d
u
ct diameter for ro
u
nd d
u
cts (in inches):
Dh = d
Dh: hydra
u
lic diameter
d: ro
u
nd d
u
ct inside diameter
Hydra
u
lic d
u
ct diameter for rectang
u
lar d
u
cts:
Dh = (2*H*W)/(H+W)
Dh: hydra
u
lic diameter
H: rectang
u
lar d
u
ct height
W: rectang
u
lar d
u
ct
w
idth
The air handler is not designed to s
u
pport the
w
eight
of d
u
ct
w
ork. D
u
ct
w
ork m
u
st
b
e constr
u
cted in a
fashion that is self-s
u
pporting. D
u
ct
w
ork sho
u
ld
b
e
straight, el
b
o
w
s sho
u
ld
b
e minimal and any
transitions sho
u
ld
b
e smooth. D
u
ct
w
ork fittings (i.e.
el
b
o
w
s, transitions, etc.) sho
u
ld
b
e located a
minim
u
m of 4' (1.2 m) from the connection. Refer to
SMACNA g
u
idelines for f
u
rther information.
Depending on the options ordered
w
ith the air
handler, flanges (either external or internal) may
b
e
pro
v
ided to facilitate connection of d
u
ct
w
ork. In
cases
w
here flanges are not pro
v
ided, flat s
u
rfaces
on the exterior skin of the air handler are pro
v
ided to
facilitate connection of d
u
ct
w
ork.
Neither the flanges nor exterior skin of the air handler
are capa
b
le of s
u
pporting the load of the d
u
ct
w
ork.
D
u
ct
w
ork s
u
pport m
u
st come from the str
u
ct
u
re itself
that the air handler is ser
v
icing. On horizontal r
u
ns, it
is recommended that d
u
ct
w
ork
b
e s
u
pported e
v
ery 6'
(1.8 m) for d
u
ct
w
ork that has a cross section of 10 ft
2
(0.9 m
2
) or less and e
v
ery 4' (1.2 m) for d
u
ct
w
ork
w
hich has a cross section of greater than 10 ft
2
(0.9
m
2
). On
v
ertical r
u
ns, it is recommended that
d
u
ct
w
ork
b
e s
u
pported e
v
ery 10' (3.0 m). On
b
oth
cases, s
u
pporting mem
b
ers sho
u
ld
b
e sized to carry
the
w
eight load.
Cut/Pinch Hazard
Wear protective gear
during installation,
operation and
service.
Edges are sharp.
Falling Hazard
Use proper safety
equipment and prac-
tices to avoid falling.
WARNING
Failure to follow these instructions can result
in death, injury or property damage.
A. Blowe
r
D. I
n
let Hood
B. V-Ba
n
k o
r
Flat Off
s
et Filte
rs
E.
I
n
let Dampe
r
C. Di
s
cha
r
ge Dampe
r
NOTE: B
urn
e
r
ha
s
co
ns
ta
n
t I
S
P = .40” w.c.
S
TA
TIC PRE
SS
URE (i
n
wc)
PERCENT OF CFM RANGE
Summary of Contents for TT Series
Page 2: ......
Page 4: ......
Page 136: ...TT SERIES INSTALLATION OPERATION AND SERVICE MANUAL 130 of 198 FIGURE 114 Regulator RV61 ...
Page 167: ...SECTION27 TROUBLESHOOTING 161 of 198 ...
Page 175: ...SECTION27 TROUBLESHOOTING 169 of 198 ...
Page 177: ...SECTION27 TROUBLESHOOTING 171 of 198 ...
Page 198: ...TT SERIES INSTALLATION OPERATION AND SERVICE MANUAL 192 of 198 ...
Page 202: ...TT SERIES INSTALLATION OPERATION AND SERVICE MANUAL 196 of 198 ...
Page 203: ...SECTION 28 THE WEATHER RITE TT SERIES WARRANTY 197 of 198 ...
Page 204: ...TT SERIES INSTALLATION OPERATION AND SERVICE MANUAL 198 of 198 ...