5 Troubleshooting and elimination of faults
NGW 300 / LGW 300 / GBW 300
502
Fig. 501 General fault symptoms (page 2 of 2)
Fault symptom
possible cause
•
Circulating pump defect
Heat exchangers (water/air) supply has too little heat,
because
•
there is air in the heat exchangers or in the system
sections
•
the heat exchange (internal/external) surfaces are
dirty
•
the air intake or output is inadequate
•
the blower has: an inadequate delivery rate / an in-
correct rotation direction / excessive resistance
•
the proportion of antifreeze agent is too high
•
the dimensions of the heat exchanger are too small
Rough estimate of the flow rate
Flow rate in [l/h] =
Heat supply [kW] according to model plate
Temperature difference
Δ
t in [K] or [°C]
between the water input and output, measured at the heater
(e.g. with a contact thermometer)
x 860
Faults in the gas supply
No fuel supply to the heater
•
empty gas tank
•
bent, closed, clogged or leaky lines
•
frozen water inlets in the gas regulator or in the
gas line
•
contaminated gas filters in the gas filter regulators
•
closed gas supply valve
•
solenoids don’t open
•
defective gas pressure regulator
•
defective vacuum switch
•
defective delayed-action solenoid
Faults in combustion
•
the speed of the combustion air fan is too low
•
defective combustion air fan
•
restricted combustion air supply
•
restricted gas supply
•
the methane content of the gas doesn’t match requi-
rements (min. 95% by volume)
•
contaminated combustion air intake grille