Weil-McLain WMB-155C Manual page 71

W
TM
AquaBalance
32 Troubleshooting
Check ignition sequence
The ignition sequence time line and operational description for the Combi boiler below help to understand the timing of the cycles.
In your troubleshooting, refer to the numbers 1 through 7 as they describe each step of the ignition cycle.
Figure 91
HEAT DEMAND PRE-PUMP TIME
DETECTION TIME
1. Heat demand detection time
CH mode: there is a confirming time of 3 seconds during
which the demand has to be always on.
The request switch is sampled every 0.2 seconds, so the
maximum delay is 3.2 seconds.
DHW instant mode: Combi boiler the maximum delay
is 0.2 seconds which is the sample time of the flow sensor.
2. Pre-pump time
CH instant mode: CH - Pump time 30 seconds.
DHW instant mode: there is no pre-pump.
3. Pre-purge time
It is the time that the fan takes to reach the ignition level
to effectively purge boiler venting.
4. Ignition
There are 0.2 seconds of preignition where the control
checks the status of the gas valve. And then there is the
park, for a time depends on the gas type:
Natural Gas, 1.6 seconds.
LP Gas, 4.6 seconds.
Part number 550-100-305/1016
M -
ALL OUNT GAS FIRED WATER BOILER
(continued)
PRE-PURGE TIME IGNITION INTER-PURGE FOR
GAS VALVE SAFETY TIME
— C
IGNITION
A01 ATTEMPTS
5. Gas valve safety time
With no flame the gas valve can be kept open for certain time:
Natural Gas, 3 seconds.
LP Gas, 4.8 seconds.
If at the end of this time the flame is not ionized, the gas
valve has to be closed and the inter-purge time for 6 at-
tempts is ran.
6. Inter-purge time for A01 attempts
There is 10 seconds of purge time before a new attempt
after a faulty ignition. After 5 attempts the boiler goes into
Lockout (code "
the boiler and to get to normal operation again, manual
reset is required.
7. Inter-purge time for A06 attempts
There is 1 second of purge time before a new attempt after
a lost flame. If the flame disappeared 3 consecutive times
within 10 minutes, the boiler goes into Lockout (code
" ) to get to normal operation again, manual reset is
required.
OMBI Boiler Manual
INTER-PURGE FOR IGNITION
A06 ATTEMPTS
FLAME LOSS
). This error condition is stopping
71