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Servicing
Exhaust gas measurements
Diagnosing and remedying faults
Exhaust gas loss
Exhaust gas loss by way of free heat will
occur as a result of the temperature
difference between the fuel-air mixture
entering the furnace chamber and the
gases discharged. Any increase in the
excess of air and the resultant higher
exhaust gas volume will cause the
exhaust gas loss to rise.
It is calculated as follows:
A
1
----------- -
q
=
t
–
t
A
A
L
CO
q
= exhaust gas loss in %
A
t
= flue gases temperature in °C
A
t
= combustion air temperature
L
in °C
CO
= carbon dioxide content in %
2
In the vent of a fault, proceed with
checking the basic conditions for a
proper operation of the boiler
system:
1. Is electric power available?
2. Is there fuel-oil in the tank?
3. Is there any gas pressure?
4. Are the shut-off valves opened?
5. Are all control and safety devices,
e.g. boiler thermostat, low water
detector, limit switches, etc. properly
set?
1. Ignition - ignition failure
Cause
Remedy
Ignition electrode
Adjust.
short circuit.
Wide ignition
Adjust.
electrode
spacing.
Dirty and wet
Clean.
electrodes.
Cracked
Replace.
insulator.
Defective ignition
Replace.
transformer.
Defective
Replace.
automatic firing
device.
Burnt ignition
Replace; search
cable.
for cause and
eliminate.
Pilot burner
Adjust ignition
failure.
gas pressure
Ignition gas valve
Search for cause
does not open.
and eliminate
Defective
Replace
solenoid.
68
A
=
1
B =
Example:
Data measured in natural gas mode:
CO
content of the exhaust
2
gases
+
B
Flue gases temperature
Air intake temperature
2
The exhaust gas loss can be calculated
as follows:
2. Motor is not running
Cause
Motor protection
relay and fuses.
Air pressure switch
not changed over
or defective.
Defective motor.
Defective power
contactor.
Fan motor starts
but stops after 20-
25 secs.
Fan motor starts,
but stops after
about 10 secs in
pre-ventilating
mode.
03/2016 - Art. Nr. 4200 1044 8002A
Fuel-oil EL
Fuel-oil S
0.50
0.490
0.007
0.007
10.8 %
195°C
22°C
Remedy
Check and replace
if required.
Check and replace
if required.
Replace.
Replace
contactor.
Check for
solenoid leaks
Air pressure switch
does not switch,
defective :
replace,
clogged:
clean,
electrical
connections:
check
Natural
Town
gas
gas
0.370
0.350
0.009
0.011
Measured values in fuel-oil operation:
CO
content of the exhaust
2
gases
Flue gases temperature
Air intake temperature
The exhaust gas loss can be calculated
as follows:
3. Pump not supplying fuel-oil
Cause
Remedy
Gate valves closed Open
Filter clogged
Clean or replace
the filter cartridge
Filter not properly
Replace
sealed
Leak in fuel-oil tube Tighten the unions
Leak in intake
Remove and clean
valve
or replace
Direction of
Check
rotation of pump
Gearbox damaged
Replace
pump
Capacity has
Replace
deteriorated
pump
- Loud mechanical noises
Pump is taking in
Tighten the unions
air
Fuel-oil tube
Clean the filter,
vacuum too high
open valves
completely
For heavy-grade
Check reheater:
fuel-oil:
Thermostat setting,
incorrect oil
cracked
temperature
dirt
Liquid gas
0.420
0.008
12.8 %
195°C
22°C
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