STANDBY, no demand for heat
Fan prepurge (10 seconds) or post purge cycle
I
gnition sequence
Burner ON for space heating (CH)
Burner ON for domestic water heating (DHW)
Pre-check for air flow prior to prepurge cycle
Burner OFF due to reaching temperature
set point
Post pump cycle for primary space heating
(1 minute)
Burner blocked:
Supply temperature too high (202 F) .Burner will
remain OFF until outlet temperature drops
below set point.
Return temperature too high (202 F). Burner
will remain OFF until temperature drops
below set point.
Return temperature is measured higher than
supply temperature. Burner will remain OFF
until corrected.
Supply temperature increased too quickly.
Burner will remain OFF for a 10 minute period.
Burner will recycle, increasing waiting period 1
minute for a max. 15 minutes
LWCO pressure device or external limit
(terminals 13 & 14) is OPEN. Burner off for 150
seconds, auto reset.
0
1
--
-
--
-
--
-
--
-
--
-
--
-
--
-
--
-
--
-
2
3
4
5
6
7
9
1
8
b
1
9
b
2
4
b
2
5
b
2
6
b
2
Display
F
unction
No blower signal
Blower signal present, Burner will remain OFF
until condition terminates
Temperature rise between the supply and return
is more than 54 F. Burner will remain OFF for
150 seconds. Burner will recycle increasing
waiting period 1 minute for a max. 20 cycle.
8
b
2
2
9
b
2
The IDWH Sensor is short-circuited.
The IDHW Sensor is not properly connected to
the low voltage terminal strip.
3
b
3
3
8
b
3
0
b
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