I installed all new components in my toilet tank using a Fluidmaster kit. Now to try to explain the problem… About every couple of minutes, the refill tube sends water into the overflow pipe for about one or two seconds. I’ve watched what is going on in the tank and can’t seem to see a problem. I do however sometimes hear a hissing-type noise from the valve top, but not always. PLEASE HELP! THE NOISE IS DRIVING ME CRAZY!!!
Make sure that you do not have high water pressure also and make sure that the refill tube that sends water into the overflow tube is not too far down inside that tube; this will cause siphonage from the fill valve and will continue to send water into overflow…..should be no more than a inch down into overflow tube.
I would first check the flapper with dye like Retired Plumber stated.
My refill tube is positioned above the overflow tube. Is that a problem? Also, should the refill tube have bends in it, or should it only be long enough to reach the overflow tube.. or does it matter? I will try the dye technique, although it is a new system and should be working. Also, I don’t hear any leakage.. but I’ll try. Thanks!