Boiler problem, comes on, but cuts off after 5 mins and whooshing sound?

1. Oil supply may be poor because of partially-blocked filter with dirt or water esp. in freezing weather. New filter element needed. It's on or near the oiltank. The whooshing sound makes oil shortage the most likely cause and the burner will lock out until button reset.
2. Soot, or a speck of dirt, on the magic-eye. If it can't see a flame it will switch the burner to lockout. (Red light on many boilers and you have to press the button to restart.) Withdraw the sensor and examine the glass at the end.
3. Faulty boiler thermostat tells it the water is hot before it is. That will NOT lock out (red light, press the button) but it will just stop until it's told by the boiler thermostat to go again. The thermostat is a probe inside a tube near the top of the boiler - it's not in the water. Remove the thermostat for a few minutes and run the boiler while you stand beside it. DON'T LEAVE IT until you've replaced the thermostat.

Peter McAnena
January 2010