Q: My toilet is causing me fits ... The problem is usually with the flapper or flush valve assembly. The flush valve (aka Douglas valve) is what the flapper sits on. It is located in the center ...

The toilet upstairs flushes good. The toilet in the half-bath downstairs will sometimes flush completely and other times the water will swirl around with some of the items being flushed.

The basics of how a toilet works haven't changed much in the last 80+ years. After a flush, water fills the toilet tank, lifting a float that shuts off the water when it reaches a certain level.