AERCO BMK 3.0 LN Natural Gas July 2011 - Manual (Page 64)

TROUBLESHO
OTING
8
-
6
TABLE 8-1. BOILER TRO
UBLESHOOTING – Contin
ued
FAULT INDICATION
PROBABL
E CAU
SES
CORRECTI
VE ACTI
O
N
HIGH GAS
PRESSURE
1.
In
cor
re
ct
su
pp
ly
gas pr
es
su
re.
2. Defe
ctive
SSOV
Actuator
gas
pre
ssure adju
stment re
gula
tor.
3.
Defe
ctive Hig
h Ga
s Pr
es
su
re Swit
ch
4.
Gas p
re
ssure
snub
ber n
ot installe
d.
1.
Che
ck to ensure ga
s p
re
ssure at inlet of SSOV is 2 psig
maximum.
2.
If gas sup
ply pre
ssure do
wnstre
am of the SSOV cann
ot be
lowe
red, to 1.8” W.
C. (se
e para. 4.3, ste
p 10), the SSOV
Actuator g
as
pre
ssure adju
stm
ent re
gula
tor may be de
fective.
3.
Remove the l
ead
s from the
high ga
s pre
ssure
swit
ch
and
measure co
ntinuity acro
ss the com
m
on a
nd normally close
d
terminals
with the unit not fi
ring. R
eplac
e the s
w
itch if it does
not
sho
w
continui
ty.
4.
See Figure 8-1. Ensure tha
t the gas pressure sn
ubb
er
is
installe
d at the high ga
s pressure switch
.
HIGH WATE
R
TEMP
SWITCH OP
EN
1.
Faulty
Water temperature swit
ch.
2.
Inc
orrec
t PID s
ettings
.
3.
Faulty shell tempe
rature sensor.
4.
Unit in Manu
al mode
5.
Unit s
etpoint is
greater than Over
Tempe
ratu
re Switch setpoi
nt.
6.
Bo
ile
r Ma
na
ge
me
nt
Sys
tem PID
o
r
other settings not corre
ctly setup.
7.
No interlock
to boiler or BMS to
disa
ble boile
r(s) in event that system
pump
s have failed.
8.
System flow rate cha
nge
s
are
occurrin
g fast
er than boil
ers ca
n
respon
d.
1.
Test the temp
eratu
re switch to in
su
re it trips
at its
ac
tu
al water
temperature setting.
2.
Che
ck PID se
ttings agai
nst
Menu D
efault s
ettings
in the
Appendix. If the setting
s h
ave been
cha
nged, re
co
rd
the curre
nt
readings
then res
et them
to the default values
.
3.
Usi
ng the re
si
stan
ce chart
s in the Appen
dix C, Measu
re the
resi
stan
ce of
Shell sen
so
r
and BTU
sen
sor at a
kno
w
n water
temperature.
4.
If unit is in Manual Mo
de switch to Auto
Mode.
5.
Che
ck setp
oi
nt of unit and se
tpoi
nt of Temperature S
w
itch;
Ens
ure that the temperature sw
itc
h
is
set higher than the unit’s
set
poi
nt
.
6.
Check
the BMS for c
hanges
to PID def
ault values
, correc
t as
necessa
ry.
7.
If system pu
mp is controll
ed by Energy
Manage
ment
System
other than B
M
S or pump
s are individu
al
ly controlle
d by boiler,
ch
eck
to s
ee if there are fl
ow sw
itc
hes
interlock
ed to the BMS or
boiler.
8.
If the s
ys
tem is
a variable flow
s
ys
tem, monitor s
ys
tem flow
ch
anges
to ens
ure that the rate of
flow change is
not fas
ter than
what the boil
ers
can
re
spo
nd to.