I have this toilet in a rental, it is an American Standard toilet. There is currently no issue, except I was thinking the tank bolts look quite corroded may be I need to replace them...and if I were to replace the tank bolts I should check if I should replace the flush and fill valves at the same time.

I noticed something that may be normal but I thought I would ask. The bowl says American Standard 1.6gpf, but inside the tank it says 1.28gpf. Does this mean the tank and bowl are mismatched - in other words, at some point someone took a tank meant for a 1.28gpf bowl and installed it onto this 1.6gpf or this is normal?





Next question, I have never seen this flush valve before. This one has a raised cylinder where the flapper sits a few inches above the bottom of the tank. What kind of design is this? I assume this is to limit the volume of the flush, but that is regulated by the fill valve float's position. Is this a American Standard special design? If I were to replace this flush valve with a standard one that sits at the bottom of the bowl, would I suddenly increase the 1.28gpf to 2.5gpf without evening adjusting the fill valve?









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Yes, it's a non-oem tank. I'm seeing references that the tank is possibly used on house brand toilets, like Lowes' Project Source and Home Depot's Glacer Bay toilets. The flush riser limits the water use per flush and might give a slight boost in momentum of the water exiting the tank.

[www.homedepot.com]



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steve, I took the label off the tank "N2412T" and did a search and came up with a tank that used to be available at the big box store: "1.28 GPF Single Flush Toilet Tank with Flapper/Piston Technology in White" with these specifications:

The NCC OPP Toilet Tank Only in White is made from ceramic for durability and features a gravity-fed flush system. The trip lever is located on the front of the tank, perfect for confined spaces. The tank uses only 1.28 gallons of water per flush for water conservation.
Highlights

1.28 GPF (gal. per flush)
Gravity-fed flushing system
Trip lever located on the front
White ceramic construction complements most bathroom decor
Compatible with N2412RB toilet bowl only

So I am surprised this tank if compatible with N2412RB bowl only is compatible with this American Standard bowl. I wonder what happened to the original tank or was it mismatched from the beginning.

Do you think it is best I look for the AS tank that is supposed to be with this bowl or leave it as is?

I am not even sure how to find the bowl's model number to make this match, or may be ten years ago someone tried and has been discontinued and this tank is the best alternative available.

If I ever had to change the flush valve to a standard one, it will most likely increase the flush volume by A LOT right?



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Some tanks are wider, front to back, and this might make a wall clearance issue if used on a different bowl. If the tank bolts up and has the proper drain size, I see no issue with mixing tanks and bowls. The American Standard tank is probably twice the cost of this one.

With a flush valve opening that is like 4" above the tank's bottom, if I replace it with a normal flush valve, it will increase the volume of flush significantly if I assume the flapper stays open the same length of time. Will this cause a flushing issue with a larger volume or do you think it will give a better flush because the bowl is designed for 1.6gpf? Or need to play with the fill valve float and overflow tube height to fine tune this?

The volume of water flushed will depend on the flapper design. If the flapper stays open the same amount of time, you should get the same volume of water flowing past it. If the bowl was designed for 1.6, the flushing quality should be better with the 1.6 vs 1.28. Flushing too much water would just be a waste of water.

steve, if you look at the flush valve design in the pictures below, the flush valve opening does not sit at the bottom of the tank like most flush valves do. There is a raised cylinder that the flapper sits on, I measured it and the raised cylinder is about 4" in height, while the tank fill valve stops filling at a tad under 8".





That means every time I do a flush roughly half the tank is emptied into the bowl for the flush, the 4" of water below the flapper stays in the tank.

I did some additional search and have confirmed this flush valve came with this NCC OPP N2412T tank.

If this tank is designed to deliver 1.28gpf, and it seems the raised flush valve opening main purpose is to limit the flow into the bowl, if I were to use a standard Fluidmaster or Korky universal flush valve that sits at the bottom of the tank, my concern is that would send 2.6gpf down this American Standard bowl unless the fill valve is adjusted to compensate, but can a fill valve be lowered that much to limit the volume?

If you had to replace the flush valve assembly and the only one readily available was a standard low rise seat, and the fill valve couldn't be lowered enough for a 1.28 flush, an adjustable flapper could be installed. This could allow a 1.28 flush with the push of the handle, but the option of a higher flush volume by holding down the handle. A standard Fluidmaster 400 has about 4 1/2" of adjustability in the tower and about 2" in the float.

Well, the tank and flush valve as design is for a 1.28gpf, the bowl from AS says 1.6gpf so I could flush more but just not that much more. I wonder how much the volume would be for a normal flush valve. The only way I can think of to find out is to wet vac the entire tank out and pour the water into a 1 gallon bottle and see how many it takes to fill. It doesn't have to be exact but if I can get it to 1.8 or so it should be good. Flushing 3g would be a waste of water and the bowl may not flush right I think.

If you are interested in the true GPF, it's not just the water that flows through the flapper, but also the bowl refill water. With the supply valve off, measure the depth of water in the bowl before flushing with your test water and top off the bowl with your test water if needed to get the same bowl water depth.

steve you think the bowl refill water through the little straw thing into the overflow tube is counted as part of the flush volume?

By the way I tried to find the answers "how would the flush volume be affected by using a standard box store flush valve instead of the included elevated flush valve" by calling the manufacturer, which turns out to be Home Depot, in other words, this Niagara brand is a Home Depot brand just like the Glacier Bay brand is a Home Depot brand, and if you call the Niagara customer service it goes straight to HD customer service and they don't know anything about any specific products, they can only answer warranty and return type general questions. Unlike Delta or Moen they actually have folks who knows their own products.