Install Instructions
40
110839-01 - 8/20
AP-U
Installation & Service Manual
Troubleshooting Flow Chart 2 – Burner Will Not Shut Down
Is
the
Red LED
(
L
O
W
WATER)
O
n?
NO
YES
The Control i
s
S
e
ns
i
ng
Low
W
a
t
e
r
.
WARNING!
TURN OFF POWER TO BURNER I
MM
E
D
I
AT
E
L
Y
!
CAUTION
–
ALWAYS ALLOW
A
BOILER TO FULLY
COO
L
BEFORE ADDING
W
A
T
E
R
.
�
Recheck wiring. Make sure that burner
is
wired
to
B1. Burner should never fire when red
or
y
e
ll
o
w
Is
e
it
h
e
r
Yellow LED
O
n?
YES
The Control
h
a
s
Reached T
a
r
g
e
t
or
High
Limit
T
e
m
p
e
r
a
t
u
r
e
.
LED
is lit.
NO
Is
the
T
h
e
r
m
os
t
a
t
(T-T)
Ca
lli
ng
for
H
ea
t
?
YES
The Control
is
O
p
e
r
a
ti
ng
Normally.
NO
The burner
will
continue
to
fire when there
is
a
c
a
ll
from
the thermostat
or
external
z
on
e
.
Is
the
E
x
t
e
r
n
a
l
Zone
(
Z
C
-
Z
R
)
Calling
f
o
r
H
ea
t
?
YES
The Control
is
O
p
e
r
a
ti
ng
N
o
r
m
a
ll
y.
NO
Is
the
Low
Limit
Dial
NO
Set
to
O
FF
?
�
Check temperature display. When the Low Limit
is
set, the HydroStat
will
fire the burner until the
temperature reaches the Low Limit
S
e
tti
ng.
YES
Is t
h
e
r
e
120 VAC between
NO
B1 and
B
2?
R
e
ch
e
ck
Wiring.
When there
is no
call
to
fire the burner, the vo
lt
a
g
e
should be
0
volts between B1 and
B
2.
�
Make sure the burner
is
wired
to
B
1.
YES
R
e
p
l
a
c
e
C
on
tr
o
l
.
If
there
is
no call
for
heat (from T-T, ZC-ZR
or Low
Limit), there should be
0
VAC between B
1
-
B
2.
�
If
there
is
voltage between B1-B2, the
control
should be r
e
p
l
a
c
e
d.
Troubleshooting Flow Chart 1 - Burner Will Not Shut Down
11 Troubleshooting (continued)