The local Toto dealer sells the TSU99A.X for $24.
So you guys recommend the 528MP over this one or the 528's that say they are
specifically for Toto? What about the "PRO" Terry mentioned in another post?
So, here's the deal. The white cap plain ol' 528 has a fixed 20 percent refill ratio. Not enough for your modern Toto, but perfect for old, old toilets. The blue cap 528T has a fixed 40 percent refill ratio. Perfect for most "S" (G-Max) Totos, too much for the E (1.28 gpf) ones, so water gets wasted.
The 528MP (with the silver cap; formerly called the "MaxPerformance," now called the "Platinum" but still numbered 528MP), the 528PRO (black cap) and the TSU99A.X (which also has a blue cap and is known by Korky as the 528GT) are essentially the same valve. Each has a variable bowl-refill adjuster. The primary difference is the color of the top, and whether it comes with Toto branding or is aimed at professional plumbers. I put a couple of PROs in where I wanted to make a good impression to anyone who would look at it later -- they couldn't tell my friend, "Oh, that's just a DIY-er product." I think that black cap looks nice. Is it worth the extra $8? Up to you. It's the same valve. Market segmentation.
I have white-cap 528s in several of our old toilets, 528Ts in our two G-Max 1.6gpf Drakes, a 528MP in our Carlyle II. I have put a couple of PROs in where I or a plumber I hired have helped out friends, and I have put silver-cap 528MPs in others. I have a PRO in the toilet in my rental apartment in the City, so anyone who looks inside will think some plumber (or at least a professional) did it.
Every one of the 528 flavors discussed above takes the R528 replacement cap, which contains the rubber-ish material that makes the seal that shuts off the water to the toilet when pressed upon by the float. I.e. the replaceable working part of the valve comes in only one version that fits all of them. It's about $3 and takes 5 minutes or less to change that cap when the valve "wears out" years from now. One part. No market segmentation.
So get whichever one you think looks nicest. Install it carefully and in accordance with the video, and you'll be in business.
One note. When you get to the part of the video where they talk about adjusting how much water goes into the bowl to refill it while the tank is refilling, the caption on the video gets it wrong -- you turn the little refill adjustment gizmo clockwise, to add more water to the refill, if the bowl doesn't refill enough. You turn it counterclockwise, to add less water to the refill, if the bowl fills up too much before the water shuts off. Easy peasy. What Jules says is correct. The caption is wrong.
