Watts AERCO Benchmark 2.0, User Manual, Page: 63 / 97

TROUBLESHO
OTING
8-7
TABLE 8-1. BOILER TRO
UBLESHOOTING – Contin
ued
FAULT INDI
CATION
PROBABL
E CAU
SES
CORRECTI
VE ACTI
O
N
LINE VOLTA
G
E
OUT OF P
H
ASE
1.
Line an
d Ne
ut
ral swit
che
d in AC
Power Box.
2.
Incorre
ct po
wer su
pply tran
sform
er
wirin
g.
1.
Che
ck hot an
d neutral in A
C
Powe
r Box to ensu
re the
y are not
re
ve
rs
ed
2.
Che
ck tran
sforme
r wi
ring,
in AC Powe
r Box, against the po
wer
box transfo
rm
er wi
ring di
ag
ram to en
sure it is wired
correctly
LOW GAS
PRESSURE
1.
Incorre
ct su
pp
ly gas pressure.
2.
Defe
ctive or inco
rrectly si
zed Ga
s
Supply Reg
ul
ator.
3.
Defe
ctive Lo
w Pre
ssure
G
as Swit
ch
1.
Measure ga
s pre
ssure up
stream
of the supply ga
s reg
ulator with
the unit firing ensure it is 1
4” WC or g
re
ater.
2.
Measure ga
s pre
ssure do
wnstre
am
of the sup
ply regu
lator with
unit firing and
adjust the ga
s su
pply reg
ul
ator to increa
se the
outlet gas p
re
ssure; if outle
t gas pressu
re can
not be i
ncrea
sed,
che
ck the si
zi
ng of the Sup
ply regulato
r.
3.
Measure ga
s pre
ssure at the lo
w gas pressure
swit
ch,
if it is
greate
r than
5” WC, mea
sure continuity
acro
ss the switch a
nd
repla
ce if ne
cessary.
LOW WATE
R
LEVEL
1.
Ins
uffic
ient water level in sys
tem
2.
Defective wat
er level ci
rcuitry.
3.
Defe
ctive wat
er level probe
.
1.
Che
ck sy
st
em
fo
r suf
ficie
nt
wat
er lev
el
.
2.
Test water le
vel circuitry u
sing the
Cont
rol Box front panel L
O
W
WATER TES
T
and RESE
T buttons. Repla
ce water
level
circuitry if it does n
ot respo
nd.
3.
Che
ck co
ntin
uity of probe end to
the sh
ell, chan
ge probe if there
is no continuit
y.
MODB
US C
O
MM
FAULT
1.
Boiler not see
ing inform
atio
n from
Modbu
s net
work
1.
Che
ck network co
nne
ction
s. If
fault persi
sts, co
ntact q
ualified
Service Pe
rsonnel.
PRG SWTCH CLOSED
DU
RIN
G
IGN
ITION
1.
A/F Valve rotated ope
n to purg
e and
did not rotate
to ignition po
sition
2.
Defe
ctive or shorted
swit
ch
.
3.
Switch wi
re
d inco
rrectly.
4.
Defe
ctive Power Su
pply Board o
r
fus
e
1.
Start the unit. The Air/Fuel
Valve shoul
d rotate to the purg
e
(ope
n) p
ositio
n, then back to ignition po
si
tion (towa
rd
s
clo
sed
)
durin
g the ign
ition cycle. If the valve doe
s not rotate b
ack to the
ignition po
sition, che
ck the
Air/Fuel Valve calib
ration.
If
calib
ration i
s okay, the pro
blem may be
in the Air/Fue
l Valve or
the Control Box. Refer faul
t to qualified servi
ce pe
rso
nnel.
2.
If the Air/Fuel Valve does rotate to the ignition po
sition
, check
the purg
e swi
tch for contin
uity between
the N.O. and
COM
terminal
s. If the switch
sho
w
s
contin
uity whe
n not in contact
with the c
am,
c
hec
k to ensure t
hat the switch i
s wired
corre
ctly
(co
rrect
wire
numbe
rs on the normally o
pen termi
nal
s).
3.
If the switch i
s wired corre
ctly, replace the switch.
4.
Che
ck DS1 &
DS2 LEDs o
n Powe
r Sup
ply Board. If they are not
steady O
N
, repla
ce Power Supply Board.