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9.0
Troubleshooting – spark ignition system
TROUBLE
Pilot burner will
not light
Pilot fails to light;
boiler locks out
Pilot lights
briefly, then locks
out
Main burners fail
to light
Caution:
Condensation can occur in the heat exchanger if boiler is
operated for long periods of time with return water
temperatures less than 120°F (49°C). Significant flue gas
condensation in the boiler will cause corrosion and premature
failure. This type of failure is not covered under warranty.
For boilers connected to large water content systems, such as
a previous gravity system with large free-standing radiators, a
bypass line from supply pipe to the return pipe can be used. A
minimum return water temperature of 120°F (49°C) can be
achieved by diverting some of the flow of heated supply water
into the flow of return water to the boiler. Valves suitable for
balancing, such as globe valves, shall be used and a
thermometer installed in the return line.
In order to assume minimum boiler water temperature
protection, the respective space heating pump must be
connected and controlled by the boiler control (refer to the
corresponding Vitotronic boiler control manual). Pumps
exceeding a rating of 120V/3A need a separate field supplied
motor starter/contactor.
CAUSE
No call for heat
Boiler temperature
too high
No power
Boiler not switched on
Low water cut-off
switch open (if equipped)
Pilot gas valve not
opening
No gas
No spark
Poor ionization
Poor ground
Gas valve fails to
open
Faulty ignition control module
REMEDY
Check that contacts on thermostat
or operating control are closed.
Allow boiler to cool and ensure
that limit controls are reset.
Check for 120 VAC power to transformer.
Check for 24 VAC power from transformer
secondary side.
Switch boiler "on" from control panel.
Check that boiler and system are
filled with water.
Check wiring to pilot valve. Replace
gas valve if necessary.
Check that all valves are open.
Bleed air from line if necessary.
Check orifice in pilot burner for
blockage.
Check electrode gap of igniter.
Check connections on high tension
cable to igniter.
Ignition module faulty. Replace.
Check condition of ionization
electrode and electrode gap. Repair
or replace. Check pilot gas pressure.
Check all ground connections back
to main power panel.
Check wiring to main gas valve.
Replace main gas valve.
Replace ignition control module.
For boilers connected to underfloor heating systems utilizing
plastic tubing with an oxygen diffusion barrier, a 4-way mixing
valve with external control or other suitable alternative must be
installed to prevent condensation and keep boiler return water
a minimum of 120°F (49°C).
Technical sales representative can be contacted to help
resolve doubts and technical questions regarding boiler
installation.
17
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