If LWCO doesn’t go off what’s the secondary safety

melo

as I am an anxious person, I was wondering say the LWCO malfunctions, what is the secondary safety if there even is one to ensure boiler turns of due to low water.

Jamie Hall

Some larger boilers have a secondary low water cutoff mounted at a lower level than the primary. The secondary should be a manual reset type — not automatic reset.

Smaller residential boilers do not have that. Some may have a fusible link of fireomatic valve in the fuel line, or a thermal cutout, in the vicinity to stop the burner if things really get wild.

HVACNUT

HVACNUT

You are the secondary safety. Checking the gauge glass.

Waher

Some LWCO units have a thermometer that even if the probe fails may be able to shut down if the temperature gets too high.

The last ditch (by which point the boiler is probably damaged and requires replacement):

Firomatic valves on the fuel line.

Some burners have a thermometer/fusible circuit link for a cut out and will lock out if detecting an abnormally high temperature.

Firomatic heat detectors/fusible circuit links above the boiler to the service switch circuit.

There’s no required cut-out connected to the pressure relief valve either, which is odd to me because it would make sense to have a circuit connection to shut off the burner if the PRV blows to reduce the likelihood someone gets boiled alive by a boiler dumping the entire steam content at 30psi into a boiler room/basement if a burner keeps firing unless a Firomatic heat detector is activated by the steam discharge.

Long Beach Ed

Some codes require a fire sprinkler over steam boilers.