Rinnai 37AHB SERIES, Installation, Operation And Maintenance Manual, Page: 44 / 68

44
Rinnai Corporation Hydronic Furnace (37AHB) Manual
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4
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
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
20
24
30
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
.
A
H
B
60 +
R
75-
L
S
i(
e)
AI
RF
L
O
W
(CF
M
)
TAP
5
(L
)
1.
5
N
E
T
H
EAT
IN
G
C
A
PAC
IT
Y
(M
B
H
)
20
24
30
A
H
B
60 +
R
75-
L
S
i(
e)
AI
RF
L
O
W
(CF
M
)
TAP
4
(M
L)
2.
0
N
E
T
H
EAT
IN
G
C
A
PAC
IT
Y
(M
B
H
)
20
24
30
M
in
im
um
Legs
@
60 C
F
M
/Leg
A
H
B
60 +
R
75-
L
S
i(
e)
AI
RF
L
O
W
(CF
M
)
TAP
2
(M
H)
2.
5
N
E
T
H
EAT
IN
G
C
A
PAC
IT
Y
(M
B
H
)
20
24
30
37 AHB06 01 2KA5 + RE U-VB2 52 8F FUD( WD )-U S
A
H
B
60 +
R
75-
L
S
i(
e)
AI
RF
L
O
W
(CF
M
)
TAP
1
(H)
3.
0
N
E
T
H
EAT
IN
G
C
A
PAC
IT
Y
(M
B
H
)
T
A
B
L
E
5
.1
2
: AI
R D
E
L
IV
E
R
Y
AN
D
P
E
RF
O
R
M
A
NC
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)
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.
TBD
See Note 6.
TBD
See Note 6.
TBD
See Note 6.
in. W.C.