Is it correct 1.28 GPF is not determined by the toilet bowl but tank?

Discussion in 'Toilet Forum discussions' started by compiler, Feb 14, 2017.

  1. compiler

    compiler New Member

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    Is it correct 1.28 GPF is not determined by the toilet bowl but tank? If so, is it possible to find a Toto 1.60 GPF tank to connect the TOTO CST454CEFG#01 Drake II bowl to make a 1.60 GPF Double Cyclone 2-piece toilet? Thank you for your answer.
     
  2. fullysprinklered

    fullysprinklered In the Trades

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    You're welcome. So you're like asking: if my wife has an identical twin sister, is it ok to take the sister on a camping trip?
     
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  4. Terry

    Terry Administrator Staff Member

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    Much of that is determined by the float on the flapper. Many aftermarket flappers are adjustable.
    That being said, the 1.28 Drake II works great the way it is. But if you want more water to drop, change the flapper out with a new adjustable, and rotate it to max.
     
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Pretty much every modern toilet tank is larger than what goes out during a flush, so adjusting when the valve closes is an easy way to adjust the actual flow volume. But, depending on where you live, it could also be illegal if you're in an area that requires 1.28g. FWIW, just like not all cars are the same, not all toilets are, either...some work better than others, with Toto right up there near/at the top.
     
  6. wjcandee

    wjcandee Wise One

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    It's determined by both. The bowl in a 1.28gpf toilet is designed to work properly with 1.28 gpf dispensed into it from the tank. It has a water spot of the proper size to initate the siphon that causes the flush.

    The tank controls what is dispensed. In a Toto with a flapper on the flush valve, then as Terry says you can adjust the flow by putting on an adjustable 3" flapper. Korky makes a couple of models of these.

    However, the Drake II works perfectly with 1.28, and the extra water isn't going to make it flush better and the extra refill water will just run out of the bowl (extra refill because adjusting the flapper to dispense more water means a longer tank refill, which means a longer period of refill water flowing, which means more refill water). Which means you don't need to mess with it.
     
  7. compiler

    compiler New Member

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    If the flapper controls the water, it should be easy to convert 1.60 to 1.28 gpf by the replacement of a flapper with an adjustable flapper. Is it correct?
     
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    It depends on the toilet...from what I have heard, Toto made the change to 1.28g from 1.6 by better calibrating the refill and the flapper valve volumes. Some toilets don't work all that well at 1.6g, so changing it to use even less could make them even less capable.

    Then, for any toilet to work well, it needs to empty the bowl, then get refilled to its design level. Depending on the bowl design, it may not get properly refilled if you reduce the flush. Some toilets essentially overfill the bowl, so it won't matter if it gets reduced some...some won't work. Typically, the bowl must be at its overflow level (i.e., as full as it can get) to flush properly the next time or you'll end up with a good flush, bad flush (but the bowl gets refilled), then a good flush.

    With an adjustable flapper valve, you could try it...it might work, it might not.
     
  9. wjcandee

    wjcandee Wise One

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    On the Toto Drake II, yes. Well, more accurately, it should be easy to increase the volume substantially. It might be 1.6, 1.8. 2.0, etc. Not sure how you would calibrate it to exactly 1.6. But you could increase it, yes. That may not be legal, and I don't advise to do it because it's basically-pointless, but yes you could do it. Get this:

    http://www.homedepot.com/p/Korky-3-in-Toilet-Tank-Flapper-for-TOTO-2023BP/205213624

    OR this http://www.homedepot.com/p/Korky-3-...0CM/202183799?keyword=toto+adjustable+flapper

    Adjust them to a setting that causes them to stay open longer.

    Eventually, you will realize that it doesn't improve the flush and, like many of our users who try this, may slowly ratchet it back to the 1.28.
     
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Note that increasing the volume used will NOT increase the water spot, if that's your goal. It might slightly improve the bowl wash, but most likely, it will just waste water.
     
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