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The
ductwork {air distribution syslemi n t ~ q t
b
de-
signed
a d dinshiled, whereby the volume
of
air blow
across thr indaor
coil
shall
never
be
less than f h w a t
standard rating mnddtims for package beat pump
slistems, Refer to tlnit air Row data* in lat ti on to ex-
ternal aatbc pressure.
or)
pages 2 ;md 3 ,
Rhwt m e b l ductwork must
be
designed and insblled
in a neat and worknmnlike manner in acwrdanm with
acwpbble industry pmctime. Informatian relative to
paomr ductwork desim, fabrication and installation
can
b e
fwnd in the following pulblimtions:
1.
ASHRAE "Guide and Dab
h F *
2. h e t Manmi a d 8 k t MehI Gonstructicrst for
Vmtilating and Air Conditioning SysLerns, *tim
I.
h w 'VIJlmity Sysbms
f iS[y
Shmt Melrrl and Air
a n d i t i m i n g Gontracbrs Natioml Agwiation,
Xnc.
1
3. Natirmal Environmenlrrl
Sysbms Contractors
A m i a t i o n Mwnurrl.
If fibrous glass ductwork is used. it must be U.L. ap-
proved as a Class
T
Air Duct with a minimum walI
thickness
of 1"
and a 3 k i pound density.
Other recommendations for proper ductwork design
and installation are
s&
CoJfows:
a. When ducts have insulation internally, the duct
size must be increased by two thlcka~esses of
in-
sulation, All seams and joint?; shall be airtight,
~moo111 fitling and taped,
h.
No
abrupt increases, decreases, offsets or W
turns without turning vanes.
c. Large ducts shall not have dilnensions whereby
the larger dimensions are greater than 4 times the
shoner dimensions. Stiffening of ducts should
have standing seams o r additional reinforcing
angles.
d. Air velocities in main ducts for residential appli-
cation should r ~ o t exceed 1000 FPM and for
branches 800 FPM.
ALldlYlieAIUM CQMDUCIOFI, PlELD WIRltrlb
InstaJI the electrical conduit to the unit through the
appropriate knock4ut and size wires in accordance to
the National Electric Code and/or the existing local
codes. When
using
aluminum conductors proceed as
foflows:
e. Branch
ducb
must have volurnc control
rdanrr~rs,
with
oubide lurking devims, to allow
the
sysknn
to be prowrly balanml
Be sure to uw prapcr
Giake
oR fittings for branch runs.
I.
Supply
and return air grilles must b e of sufficient
SIZF, n u m k r and lmation to prrvent djectionable
drafts, pltth providing Imlancrd
:air
circkalation
g
Supply
arrd returrr air hr:anch ducts
s)r:tIX
have
a
minimunr din~ensron
trf
6"
rourld
or
equal
h
A l l
ducbuork
m11.;t
!w sarrl~ltorted wrt h ntek+l
straps
to
prt-vent
sagging
j.
It is
not recommended that two units discharge
the supply air into a common duct. Each unit
should have its own srrppliy and rcturn air duct
system.
Indoor supl>ly :~nd returrl dircts
cxpowd
to
near oub-
tlwr
I C I * I ~ ) C ~ ; B ~ U I C
m u ~ t t)c
insti1:~t~d with
n
nrlnlrnlrrn rrf
2'3L1;erglnh or ()quai Iluttt~ork crj)osc.d
to
the
outdwr
elcrnents must
have
two inches
of
insulation , ~ n d
a
wcntheri>rmf barrier.
Xnsidc cluctwork witl-rin
thr
conditional space may be
insulated
with
5''
fii>erglas intcmnl
or
externally with
a
vapor barrier.
Vapor b:irricrs, such as aluminum foil, or
equal,
shall
Inp
a minimum
of
three inches at a21 Iongitudinal and
butt joints These joints rrlust
hc
securely seal& and
s h p l d .
All
~>uncturc-s, tears, or imperfections in vapor
barrier must
be
patched
with
same makrial and
adhesive
Ductwork in or lwlovv a slab flmr must
be
wmplelely
encawd in !lot less than
2
inches of ct3ncretc and
shall
be
insulattbd
and
vapor-scaled in addition to the slab
prirnebr insulation insulation shall
brt n
minimum
of
I",
one pound density, fikrglas
or
equal
A1I insulating
mirsr he
pe~c?rmed in a kvorkmrrr~like
nlitnner ;knd inlsralled
in
a hshion as recommended by
the manufacturer of the insulation and vapor barrier.
3.
Spliim
mppr
wire
pigbils
to alurrainum wim with
U. L. r ~ o m i z e d c o n n ~ t t ~ r s for mpper alunrrinlllxrr
splices. (See rabulatior~). Please exercise the fol-
lowing insir-uctions very carefully to <?blain a
good connection:
a. Strip insulation from aluminum crcmduclor.
t j .
t ' t x i t
iiic
S I I . I ~ ~ ~ L I
c i ~ d
t>f
1 1 ~
A L : I I I I I I ~ I ~ ~ I
u
ire
u i t i ~
C'AU't'IfJPu:
Ilu
nttt
connect alctn~inum wires
to
the
(IIc,
k ~ , ~ L ~ o ~ ~ i n ~ c n ~ j ~ ~ ~ i
i i ~ i ~ i b i t o r
{See
t:ii?~~l:itii~rl)
; ~ I ~ L I
unit cil.cuit
breaker-
terniinitls.
N I ~ C
ht11511
: ~ i i i n ~ i r i t ~ i ~ ~
$ ~ r f : i < ~
~ I I I W I ~ I I
~ r ~ h i t > i i % ) t
1. ,%lc3ct
the quivalent aluminum wire size
from
the
Csbulation b l o w :
c. Clean and r m a t aluxninum conductor with in-
hibitor.
d. Make the splice using the listed wire nlits or
split twrlt connectors.
e.
Cwt
entire connwtion
wit11
inhibitor and wrap
with
elr;etrieal insulating
hpc.
I N HIBITOR:
T &
B
-
Aluminum joint compound or
equal
3.
Attach n
length
(h"
or more) ofrecnntmended size
cclpper wlre to the unit circuir breaker-
S W I ~ C I Z
~ c r r n ~ ~ ~ ; t l \ ~
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