A.O. Smith 28 30 50 60, Installation & Service Manual

Page: 76 / 96

is
Release R
.1.3
UK
76
Wa
rn
in
g
Ma
intena
nce may
o
nly be pe
rformed
b
y a
qu
alifie
d se
rvi
ce and main
te
nance
e
ngin
eer
.
F0
3 (lo
ck ou
t
e
rro
r)
The pressure switch fails
to work cor
rec
tly
.
Damage
d wiring
/
O
pen
c
irc
ui
t
1.
C
heck the
w
iring be
tw
een the pressure
swi
tch an
d the
co
ntro
ller
.
2.
If
n
ecessary
, rep
lace the wirin
g.
If the
e
rro
r can
not b
e
resolved
o
r is
pe
rsi
sten
t,
cont
act you
r
in
st
a
lle
r.
To
rep
lace
the
ne
ce
ssary p
a
rt
s, yo
u mu
st
cont
act you
r in
st
al
ler
.
P
res
sure switch not
cl
os
ing
.
1.
C
heck the
ru
nnin
g sp
eed
o
f the fa
n.
See
’8
.7
.4
Di
sp
la
yi
ng
a
ppli
ance spe
ci
fic
ati
ons’
.
2.
C
heck that
the
ho
ses o
n the
pressure
switch a
nd
th
e a
ir sup
ply
h
ose b
etween
fan
and
burn
er are
correctly fitted. Re
fit the
se if
necessary
.
3.
C
heck the
h
oses on the pressure switch and
the
a
ir
su
pply
h
ose b
etween
fan
and
burne
r for cracks. If n
ecessary
, repl
ace
th
e ho
se
s.
4.
C
heck whether the fl
ue ga
s
di
sch
arge is compli
ant with
Ta
bl
e
3.
7
.
5.
C
heck
for
bl
ockage
in
the
flue
g
as d
ischarge
. Remo
ve
a
ny
b
lockag
e
tha
t may be presen
t.
6.
C
heck for bl
ockage in
the
con
densa
tion water discha
rg
e.
R
emove any blo
cka
ge that
ma
y be
p
re
sent.
7.
Mea
sure th
e pressure dif
fere
nti
al across th
e pressure switch.
See
Ta
bl
e
12
.1
. If there is insuf
ficie
nt
p
re
ssure dif
feren
tia
l,
cl
ean the hea
t excha
nge
r.
If
the
p
re
ssure dif
ferentia
l is
a
cce
pt
able
, check that
the
p
re
ssu
re
sw
itch
is
clo
sing,
using
a
mu
ltim
et
er
.
Ta
ble
10.2
Displ
ayed errors (Shee
t 4 of
1
0)
Co
de
+
De
scrip
tio
n
Po
ss
ib
le
c
aus
e
S
o
lu
tio
n
R
emar
k