Just had two Toto Drakes installed to replace Gerber toilets. The plumber who did the job had never worked with Totos before, so I'm not sure if this is a problem or not and after talking to him, he doesn't know either. After a flush, one of the toilets makes an on and off hissing noise in addition to the sound of the water filling the bowl again. It's on the upstairs toilet, so I'm not sure if it could be a water pressure problem or nothing to be concerned about as long as they work properly. Thanks for your help.
If the fill valve looks like this, it the assembly cap may need cleaning.
If the valve has an adjustment screw, it needs something else.
The tanks have had both valves lately.
The valve can spit a bit when filling, but should stop at some point, and keep quiet after that.