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Boiler Shut Down

Boiler Chart Q:  My boiler keeps shutting down. What could be causing


A: There are many causes of a boiler shut off. One possible cause is called low water cut-off. Low water cut-off prevents serious damage to the boiler by cutting off the burner if the water level in the boiler should drop too low. There are three things that must be in place for a boiler to operate properly: water, fire, and the recommended steam pressure.

Each of these items has to be in a perfect working order as preset by the manufacturers. Water in a boiler is filled by an electric pump called the feed pump. This feed pump automatically cuts off when water in a boiler reaches a required level. This is the time when the fire ignites. The fire in a boiler only ignites when a boiler is filled up with a required water level.

During smooth running conditions the fire will cut off when a required steam pressure is achieved, which means the water has turned into high-pressure steam. While the steam is being consumed in a plant the water level in the boiler is gradually going down. At a pre-set low level of water, the feed pump will turn on to bring up the required water level. The fire will ignite again at the required level. A low level of water prevents the boiler from igniting.


The cause of low water level in the boiler is mainly due to the malfunction of a “check valve.” This valve is situated on the water feed line connecting the boiler and the feed pump. The purpose of having this valve on the feed line is to prevent steam from backing out of the boiler to the feed pump. If the check valve is malfunctioning, the steam from the boiler will pass into the feed pump. When the feed pump turns on it will be filled with steam, which it cannot pump. No water will be going into the boiler. Thus, the boiler will shut down because of the improper water level.

Solution: The “check valve” needs to be replaced.

Posted By Harry Kimmel | 3/4/2016 2:01:58 PM