Installation Instructions

Troubleshooting | 45
6 720 805 218 (2016/02)SB625WS/SB745WS
10 Troubleshooting
Problem Cause Troubleshooting
The boiler does not reach its set temperature. Heat exchanger dirty. ▶ Clean the flue gas pipes.
Heat exchanger and burner mismatched.
▶ Check specifications and settings.
Insufficient gas flow burner.
▶ Check and adjust the burner.
Control thermostat problem.
▶ Check the functioning of the aquastat.
▶ Check the temperature setting.
The boiler keeps shutting down, and the control
panel warning light comes on.
Control thermostat problem. ▶ Check the functioning of the aquastat.
▶ Check the temperature setting.
▶ Check the electrical wiring.
▶ Check the sensor bulbs.
No water supply. ▶ Check the circuit pressure.
Air in the circuit. ▶ Check the vent valve.
The boiler has reached the set temperature but
the radiators are still cold.
Air in the circuit. ▶ Bleed the circuit.
Pump malfunctioning. ▶ Check/release the pump.
Problem with minimum temperature aquastat (if
present).
▶ Check the temperature setting.
There is a smell of fumes. Fumes are escaping into the air. ▶ Check that the boiler body is clean.
▶ Check that the flue pipes are clean.
▶ Check that the boiler, flue pipes and flue gas
exhaust stack are all properly sealed.
The safety valve keeps opening. Excessive pressure in the circuit. ▶ Check the circuit pressure.
▶ Check the functioning of the pressure
reducer.
▶ Check the settings of the pressure reducer.
Problem with heating system expansion vessel. ▶ Check the efficiency of the expansion vessel.
There are traces of condensate on the rear head. Flue gas box seals. ▶ Check the seals between the rear head and
the flue gas box.
Table 22 Troubleshooting