What is a low water cutoff switch?
A low-water cutoff is a mechanical device (usually a float switch) that is used to turn off the burner or shut off fuel to a boiler to prevent it from running once the water drops below a certain point. If a boiler is “dry-fired” (burned without water in it) it can suffer rupture or catastrophic failure.
How often must you flush a float type low water cutoff?
Low-water fuel cutoffs should be flushed daily for steam boilers operating at more than 15 psig and weekly for those operating at less than 15 psig.
What causes low water in boiler?
Some common causes of low-water conditions include: Feedwater pump failure. Control valve failure. Loss of water to the deaerator or make-up water system.
How do you flush a low water cut off?
Purging is accomplished by slowly opening the valves in the LWCO drain line. The flow flushes out the float chamber and connecting piping. If the valves are opened too quickly, the resulting flow can cause the float to jerk downward in the float chamber.
What causes low water level in boiler?
Some of the common causes include: Feedwater pump failure. Control valve failure. Loss of water to the deaerator or make-up water system.
What does McDonnell and Miller low water cut off do?
Selection Tool McDonnell & Miller Low Water cut-offs are specially designed to protect steam and hot water boilers from the hazards of a low water condition. In operation they will interrupt the electrical current to the firing device, if the water in the system drops below the boiler manufacturer’s minimum safe water level.
How often should a McDonnell and Miller probe be used?
These controls are used as the secondary LWCO on steam boilers and can be used as the primary LWCO on hot water heating boilers. With a self-cleaning probe, available only on McDonnell & Miller probe type controls, which reduces probe maintenance to once every five years instead of annually.
Is there a lock out if probe is in water?
No lock out with loss of power if probe is in water McDonnell & Miller is a leader in engineering and manufacturing boiler controls, liquid level controls, low-water cutoffs, and flow switches for steam and hot water boilers in industrial, commercial, and building trades applications.
When do you use a low water cutoff?
A low water cutoff is a device that detects when the fluid level in hot water and steam boilers drops below the minimum safe operating level specified by the boiler manufacturer. If this should occur, the low water cutoff will cut-off the burner and shut down the boiler.