Can a 1.28gpf Toto be converted to a 1.6gpf Toto?

Discussion in 'Toilet Forum discussions' started by Wallijonn, Mar 23, 2014.

  1. Wallijonn

    Wallijonn Member

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    136
    Location:
    Arizona
    If you consider the differences between the Drake CST743S 1.6gpf and the CST743E 1.28gpf being the fill valves and flush valves, TSU24A & THU129W-A and TSU53A & THU252P-A respectfully, since both use the same bowl, CST743E, is it possible to convert the Drake II CST454CEFG to 1.6gpf in the same way?

    Now, you may be asking, why would I want to do that? Because to get SanaGloss on the Drake I'd have to go with a 14+5/8" bowl (CST744SG) instead of the ADA 16+1/8" bowl and I really prefer the Drake & Drake II sleek bowl look to the Promenade's blocky front bowl (which makes me think of a 1930's toilet or hospital toilet.)
  2. wjcandee

    wjcandee Wise One

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    The Drake II works fine on 1.28gpf. Most of the difference between 1.6 and 1.28 has to do with the water spot size, construction of the bowl, etc. Some of it is the flush, but some of it is the other stuff. If you for some reason you want more water in the flush, you get the Korky 3" Adjustable flapper and set it a number or two higher than the proper number for the Drake II. It will float open a little longer and drain the tank a little more.

    But you won't need to do so. Just get the Drake II. Everyone loves it. It's routinely the most popular toilet of any brand on one of the big consumer-product web sites. As you point out, the "base" model has a lot of standard features.

    (Don't get the Drake II 1G (CST454CUFG), because it has a different flush valve, one without a flapper. The CEFG has a flapper.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    All you need to do is change the flapper valve, but I'd suggest you just try it with the stock 1.28g, and only tweak it if it doesn't do what you want...most people are surprised at the efficiency of the lower flow toilets, and you may not know, they now also make a 1g version which also works.
  4. Wallijonn

    Wallijonn Member

    Messages:
    136
    Location:
    Arizona
    I thought that if it had the grenn Emax that you would change it to the red G-Max, change the flush valve (with the flapper) because the top has to line up with the mark on the fill valve.

    Now my concern is that if it is increased to 1.6gpf that there will be splashing inside. And yes, the smaller water spot size does concern me. The two or three 1.28gpf toilets I've seen at work left me cold and totally not impressed. The one Eljer 1.6gpf toilet at work is amazing - woosh it goes down the drain like greased lightning. My Briggs? Forgetaboutit - maddingly frustrating; made in 1979 it probably is a 3g flusher and 50% of the time I have to flush twice.
  5. wjcandee

    wjcandee Wise One

    Messages:
    1,830
    Location:
    New York, NY
    No. As far as flapper choice, it's not that simple. As far as everything else, it's not that complicated. Want a little more water in the flush? You just change the setting on the Korky adjustable replacement flapper. Using what you are calling the GMax flapper won't necessarily dispense the right amount. In fact, that flapper is used in a number of the 1.28gpf toilets, because they are designed to dispense the right amount of water to do a 1.28gpf flush with the flapper opening and closing as that one does.

    Again, you're going to be happy with the 1.28, and changing it to 1.6 (or 3.5) isn't really going to affect whether it clogs or not. That's more a function of the trapway design, which on the Toto is excellent.

    No, there won't be splashing. You're really overthinking this, I have to tell you. .3 of a gallon is a little more than a quart of water. It's just a matter of squirting the water for another second or less to dispense that additional water.

    The water spot on the Drake II is a pretty-good one. And, as I am sure you know, when the bowl is properly-refilled, any additional water would just run over the weir of the trapway and down the drain, so trying to increase the refill water isn't going to increase the size of the water spot.
    Last edited: Mar 24, 2014
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Location:
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    There's a limit on how big the water spot can be based on the amount of water used to flush the toilet. You have a choice, wide and shallow, or narrower and deeper. Since ALL of the water in the bowl must be replaced EVERY time it is flushed, the amount in the bowl cannot be more than the amount you use to flush...you want it all to go down the drain, not just dilute it somewhat. And, when refilling, it must get refilled to the normal, full level, or it will not flush properly the next time (the float only determines the tank fill, the bowl fill must be calibrated to match). This is why the fill valve needs to be adjusted for that specific toilet. Older ones just dumped excess water down the drain, but the goal is to refill the bowl AND the tank at exactly the same time, and not waste extra water (any that exceeds the max on the bowl will just drain out on its own).
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