Rinnai 37AHB SERIES User Manual
Page 40

40
Rinnai Corporation Hydronic Furnace (37AHB) Manual
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7
Ma
xi
m
um le
gs
@
40 C
F
M
/Leg
13
16
N
um
ber
of
3"
Di
am
et
er
B
ranc
h Legs
appl
ic
ab
le
t
o H
ig
h
V
el
oc
ity
S
ys
tem
s O
nl
y.
U
sed onl
y i
f m
et
hods
ot
her
than T
abl
e 3 i
s us
ed t
o det
er
m
ine duc
t s
iz
es
.
M
in
im
um
Legs
@
60 C
F
M
/Leg
O
pt
im
al
L
egs
@
50 C
F
M
/Leg
Ma
xi
m
um le
gs
@
40 C
F
M
/Leg
M
in
im
um
Legs
@
60 C
F
M
/Leg
O
pt
im
al
L
egs
@
50 C
F
M
/Leg
Ma
xi
m
um le
gs
@
40 C
F
M
/Leg
13
16
20
1.
5
N
E
T
H
EAT
IN
G
C
A
PAC
IT
Y
(M
B
H
)
N
E
T
H
EAT
IN
G
C
A
PAC
IT
Y
(M
B
H
)
13
16
20
A
H
B
45 +
V
53
i
AI
RF
L
O
W
(CF
M
)
TAP
5
(L
)
AI
RF
L
O
W
(CF
M
)
TAP
3
(H)
2.
0
N
E
T
H
EAT
IN
G
C
A
PAC
IT
Y
(M
B
H
)
20
M
in
im
um
Legs
@
60 C
F
M
/Leg
A
H
B
45 +
V
53
i
AI
RF
L
O
W
(CF
M
)
TAP
4
(M
)
2.
0
O
pt
im
al
L
egs
@
50 C
F
M
/Leg
T
A
B
L
E
5
.8
: AI
R D
E
L
IV
E
RY
AN
D
P
E
RF
O
R
M
ANC
E
D
A
T
A
(
B
O
T
T
O
M
O
R
S
ID
E
RE
T
URN
w
/ F
A
C
T
O
R
Y
S
U
P
P
L
IE
D
F
IL
T
E
R
)
UN
IT
SIZ
E
EC
M
SPE
E
D
TA
P
SU
PP
O
R
T
S
CO
O
L
IN
G
CAP
.
RANG
E
(T
O
N
S
)
E
W
T (
O
F)
NO
M
INAL
HE
AT
IN
G
CA
P
ACI
T
Y
E
x
te
rn
a
l St
a
tic
Pr
e
ss
u
re
(
E
SP)
37AH
B04
508KA
5 +
RE
U-V
B2020FF
UD
-U
S
A
H
B
45 +
V
53
i
N
O
T
E
S
:
1.
E
W
T
- En
teri
ng
W
ater Tempe
ratur
e (F)
.
2.
CFM - Air
flow
in (C
ubic Feet per
Minute).
3.
Legs - 3
in
ch
diame
ter
flex
ible du
cts to
diffu
ser
s.
4.
1 MBH =
1000
BTU/H.
5.
Shaded b
ox
represents ra
ting
poin
t; re
fer
to
w
iring diagra
m
for
factory
se
t sp
eed
taps.
6.
Number of 3”
diam
eter
leg
s
spe
cifi
ed i
n ta
ble a
bov
e is
fo
r
rating
poin
t o
nly
(i.e
. a
t Ex
ternal S
ta
tic
Pres
sure
of
0
.5
in. w
c. and
speed
TAP3, TAP1, TAP2
, TAP2
for
AHB45
, AH
B60, AHB75, A
H
B90 re
spe
ctiv
ely
). Final
leg
count i
s
to b
e de
termined
b
y the in
stalli
ng
con
tractor
and i
s to
be
based
on
the
follow
ing formula:
NUMBER OF LEG
S
= TOTAL
AVA
IL
ABLE CFM
(A
T THE S
PECI
F
IC
E
SP)
/ DESI
RED CFM per LEG
(40, 50, or 60 CF
M)
Ex
ample: Giv
en the
design
point
for
A
H
B045 o
f 0
.8
ESP
, Low
fan
speed
(Ta
p5). From
tabl
e 5
.0
, av
ailable CFM i
s
569 and
the d
esir
ed CFM per
leg
is 50
CFM.
Therefore,
Number of Leg
s =
569/50
= 11
.38
rou
nded dow
n to
11
.
TBD
See Note 6.
TBD
See Note 6.
TBD
See Note 6.
TBD
See Note 6.
TBD
See Note 6.
TBD
See Note 6.
in. W.C.