42
Rinnai Corporation Hydronic Furnace (37AHB) Manual
0
0
.1
0.
2
0
.3
0.
4
0
.5
0.
6
0
.7
0.
8
0
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1.
0
948
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868
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819
795
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7
0
1
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31.
7
30.
8
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8
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0
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1
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4
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6
25.
8
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4
19.
9
19.
0
130
38.
4
37.
3
36.
1
35.
1
34.
0
33.
2
32.
2
31.
3
28.
4
24.
1
23.
0
140
45.
2
43.
9
42.
5
41.
4
40.
1
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0
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9
36.
8
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4
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4
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150
51.
4
49.
9
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3
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1
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6
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0
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3
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58.
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6
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4
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5
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2
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2
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2
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50.
8
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2
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7
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1
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8
43.
5
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4
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9
38.
6
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8
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8
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57.
0
55.
2
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5
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8
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3
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8
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6
45.
9
43.
3
36.
8
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6
803
768
740
712
682
652
628
596
5
6
9
541
51
0
120
29.
5
28.
2
27.
1
26.
1
25.
0
23.
9
23.
0
21.
9
20.
9
19.
8
18.
7
130
36.
2
34.
6
33.
3
32.
1
30.
7
29.
4
28.
3
26.
8
25.
6
24.
4
23.
0
140
42.
0
40.
1
38.
7
37.
2
35.
6
34.
1
32.
8
31.
1
29.
7
28.
3
26.
6
150
47.
5
45.
4
43.
7
42.
1
40.
3
38.
5
37.
1
35.
2
33.
6
32.
0
30.
1
160
53.
6
51.
3
49.
4
47.
5
45.
5
43.
5
41.
9
39.
8
38.
0
36.
1
34.
0
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
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
A
H
B
45 +
R
94-
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
)
13
16
20
A
H
B
45 +
R
94-
L
S
i(
e)
AI
RF
L
O
W
(CF
M
)
TAP
4
(M
)
2.
0
N
E
T
H
EAT
IN
G
C
A
PAC
IT
Y
(M
B
H
)
13
16
20
M
in
im
um
Legs
@
60 C
F
M
/Leg
37
AH
B0450
8KA
5 +
RE
U-V
B27
35FFU
D(W
D)-
US
A
H
B
45 +
R
94-
L
S
i(
e)
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
)
13
16
20
T
A
B
L
E
5
.1
0
: 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.
in. W.C.