Toilets, Sinks, Showers, Tubs and Disposals - Critical level vs. fill tube

The instructions for my new Fluidmaster 400a flush valve say that the C.L. (critical level) mark near the top should be at least one inch higher than the top of the fill tube. I think if I do that, the top of the valve will protrude above the tank too much and prevent the tank top from closing completely. Is this a case to hacksaw some off of the fill tube?

I am replacing an older Fluidmaster of the same type. Is the 1" a new requirement?

B

The WATER level should be 3/4" lower than the overflow tube. I can't see where anything else matters. My new toilet came with a Fluidmaster 400 and thats all it says.

The 1" is a requirment for cross connection control. It's 1" or double the pipe size for an air gap.

Your tank lid should have an inward bow build in to it to allow some room for the valve also.

Good luck with your project.

The new Fluidmaster is in. It does protrude up higher than the sides of the tank but as one of you said, the tank lid has space for it. The C.L. line is probably only about 3/4" from top of filler tube but I have valve set to stop filling with water at least 1" below top of filler tube.

Aside from the ongoing problem not being able to get the old tank bolts out (other thread), my new problem is that the supply tube is now leaking. It is one of these woven material hoses with the ends fixed on. It is about 9" long where all I need is about 7" and I couldn't seem to prevent it from twisting and kinking as I tightened the upper end to the tank. So I took the lower end off of the supply valve, tightened the upper end, and put it back on the lower end but it's the lower end that now leaks badly. Guess I got to buy a new one.

B