AERCO BMK 3.0 LN Natural Gas July 2011 - Manual (Page 68)

TROUBLESHO
OTING
8-10
TABLE 8-1. BOILER TRO
UBLESHOOTING – Contin
ued
FAULT INDICATION
PROBABL
E CAU
SES
CORRECTI
VE ACTI
O
N
RESIDUAL
FLAME
1.
SSOV not fully closed.
2. Defe
ctive
Flame
Dete
ctor
1.
Check
open/clos
e indicator wi
ndow of Safety Shut-Off Valve
(SSOV) and ensure that the SSO
V is
fully c
los
ed. If n
ot fully
clo
sed, re
pla
ce the valve and or a
ctuat
or.
Clo
se ga
s sh
ut-off valve down
stre
am of
SSOV. Install a
manom
eter o
r gaug
e in a g
as test po
rt b
etwee
n the SSOV and
the gas
s
hut
off valve.
If a
gas
pr
es
su
re
r
ea
din
g is
obs
er
ved
repla
ce the S
S
OV valve and or act
uator.
2.
Repl
ace Fla
m
e Dete
ctor.
SSOV FAULT
DU
RI
N
G
PU
RGE
See SSOV SWITCH OPEN
SSOV FAULT DU
RI
N
G
R
U
N
1.
SSOV swit
ch
clo
sed
f
or
15
s
ec
ond
s
durin
g ru
n.
1.
Repl
ace or a
djust micro
swi
tc
h in SSOV ac
tuator. If fa
ult
persist
s, repl
ace a
ctuato
r.
SSOV RELAY
FAILURE
1.
SSOV relay failed on b
oard.
2. Floating
Neut
ral.
3.
Hot and
Neut
ral reve
rsed a
t SSOV.
1.
Press CLEAR button an
d resta
rt un
it. If
fault pers
is
ts, replace
Ignition/Stepp
er (IGST
) Board.
2.
The Ne
utral a
nd Earth G
ro
und
are not conne
cted at the so
urce
and therefore
there is a vol
tage mea
su
re
d betwe
en th
e two.
Normally this
measurement
shoul
d be ne
ar ze
ro o
r no
more tha
n
a few millivolts.
3.
Che
ck SSOV powe
r wi
ring
.
SSOV
SWITCH OP
EN
1.
Actuator n
ot allowin
g for full clo
sure
of gas valve
2.
SSOV powe
red wh
en it sh
ould not
be
3.
D
efec
tive Switc
h or Ac
tuator
4.
Inc
orrec
tly wired switch.
1.
Observe op
eration of the Safe
ty Shut-Off Valve (SSOV) through
indicator on t
he Valve actu
ator and e
nsu
re that the valve is fully
and not pa
rtia
lly closin
g.
2.
If the SSOV n
ever c
los
es
, it may be powered
co
ntinuous
ly.
Clo
se the ga
s supply an
d remove po
we
r from the unit. Refer
fault to qualified se
rvice p
er
so
nnel.
3.
Remove the
electri
cal
cov
er from the S
S
OV and ch
eck swit
ch
continuity. If
th
e switc
h does
not s
how
co
ntinuity w
ith the gas
valve closed, either adj
ust
or re
pla
ce the
switch or a
ct
uator.
4.
Ens
ure that the SSOV Proof of Clos
ure
sw
itc
h is
c
orrec
tly wired.
STEPPER MOTOR
FAILURE
1.
Air/Fuel Valve out of calibration.
1.
Refer to GF-112 and perform
Stepper Te
st (pa
ra. 6.3.5) to
ensure
stepp
er moto
r rotat
es prope
rly b
etwee
n the 0
%
(fully
clo
sed
) and 1
00% (fully op
en) po
sition
s.
Verify that th
e
VALVE
POSITION b
arg
rap
h and t
he dial on the
Air/Fuel Valve track
each other to
indicate pro
pe
r ope
ratio
n. If operation is not
co
rr
ec
t, p
er
for
m th
e Ste
ppe
r F
eed
ba
ck
C
alibr
at
io
n
(G
F
-11
2,
para. 6.2.1
).