What is a low water fuel cut-off?

A low-water fuel cutoff is used on both steam and hot water boilers to shut off the fuel or source of heat when the water drops below a predetermined, safe operating level. The most common type of low water fuel cutoff is a float inside a chamber. Some low-water fuel cutoffs have a manual reset device built in.

How does a low water cutoff work?

To help prevent damage and possible injuries, boilers are fitted with low water cutoffs (LWCOs). These devices are intended to detect the low water condition and shut down the boiler. The burner remains off until the water returns, then the burner is allowed to fire normally.

How often should low water fuel cut-off controls be tested on a low pressure steam heating boiler?

Be Careful When Testing Never allow the water level to drop out of sight in the water gage glass. 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. Be sure the burner stops when the water level drops.

When to test the low water fuel cutoff device?

Boilers shall not be operated when the water level is not visible in the gage glass. For steam boilers, a daily test of the low-water fuel cutoff device is recommended by CSD-1, which also recommends performing a semiannual slow drain test of the low-water fuel cutoff device.

What do you need to know about low water Cutoff controls?

Boiler low water cutoff control service or repair: Here we explain Low Water Cutoff Controls: Guide to LWCOs on steam heating and hot water heating systems and we provide a low water cutoff switch Troubleshooting & Repair Guide.

Why do you need a low water cutoff on a boiler?

Both techniques merely detect a low-water condition caused by some other problem in the boiler. For that reason, inspectors must look beyond a cutoff device failure to find the root cause of a boiler’s low-water condition. “Low-water cutoff devices are like anti-lock brakes,” Mr. Thomson says. “They help prevent accidents.”

How to test a low air pressure cut off?

The low gas pressure cut-off can be tested during the operation of the boiler by slowly closing the main gas cock. Observe the pressure gauge on the gas line. When the pressure in the fuel line drops to the cut-off point, the burner valve should shut automatically. Testing Low Air Pressure Cut-Off