Toto Drake fill rate - can it be adjusted?

Discussion in 'Toilet Forum discussions' started by Smith333, Apr 16, 2008.

  1. Smith333

    Smith333 Member

    Messages:
    107
    Over the past 6 months I've installed 2 drakes, both work great except for the fact that the waterspot is extremely low, unless you hold the handle down for about a half second while flushing. Well, today I installed a third Drake, and was shocked to see that it got the maximum water spot without holding down the handle. It seems the difference is that the fill tube flows at a much faster rate in the newest Drake than the previous two. Visually, there is no difference between all three toilets (ie, the fill tube is not kinked). Is there any way to increase the fill tube flow rate on the Drake?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    21,896
    Location:
    New England
    Take a bucket of water and SLOWLY pour it into the bowl of the toilet, then let it sit to see where the height of the water ends up.

    Is the fill level in the tank the same? It's normally somewhere around 1/2" below the top of the overflow tube.
  3. Smith333

    Smith333 Member

    Messages:
    107
    Yep, the fill level in the tank is the same for all three toilets. The same is true with the maximum waterspot.

    I should clarify my first post - I'm referring to the flow rate of the flexible tube that discharges into the overflow tube. That flow rate is MUCH faster in the newest toilet compared to the previous two. The result is that a lot more water is discharged into the bowl after the flush, while the tank fills, therefore producing a much larger waterspot in the same amount of tank refill time.

    Is there any way to increase that flow rate so that I can get the maximum waterspot in the other two toilets without holding down the flush lever?
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,896
    Location:
    New England
    Take the cap off of the fill valve (it just snaps off assuming it is the Korky) and check to see if the hose might be kinked or leaking there.

    Is the actual total flow rate the same? Is the shutoff valve of the slow one fully open?
  5. Smith333

    Smith333 Member

    Messages:
    107
    I have done some quantitative testing and this is what I've found.

    The two older Drakes have a flush cycle time of about 25 seconds (average) and discharge 4-1/2 cups of water into the bowl. The fill valves look to be of different designs. These toilets are in the same house on a well.

    The newest Drake also has a flush cycle time of about 25 seconds (average) but discharges 6 cups of water into the bowl. The fill valve matches what is in one of the other Drakes. This toilet is in a different house that is also on a well.

    With these facts in hand, what could be causing the new Drake to discharge 33% more water into the bowl in the same amount of time? It may not seem like a whole lot, but it makes a big difference on the size of the waterspot. Is there anything I can do to make the other Drakes work like the new one?
    Last edited by a moderator: Apr 20, 2008
  6. Smith333

    Smith333 Member

    Messages:
    107
    I found the page for the Korky replacement fill valve ( http://korky.com/FillValve528T.html ) and found this to be interesting...

    "Higher refill ratio for optimum performance in TOTO toilets"

    Sounds like this addresses my problem...but here's the catch...One of the our two Drakes with the lower bowl refill rate has a fill valve that looks just like this one. Anyone know if the Korky 528T is a new model that came out in the past 6 months or so? I may just spend the $25 for one to find out.
  7. Smith333

    Smith333 Member

    Messages:
    107
    I had a chance to call the Toto technical support and described my problem to them. The guy said that it is normal to have to hold the flush lever down for about 1 second to get a full 1.6 gallon flush and have the bowl fill to the correct level. When questioned again why the new toilet did not have to have the flush lever held down to get a full bowl, he sort of hem and hawed and decided it must be because they sent me a 1.28 gpf bowl. I checked again and there is no visible difference between any of the three toilets.

    This information seems contrary to what I've read here about how the Drake is supposed to be flushed. It looks like I will have no choice but to buy a new 528t replacement valve and see if that solves the problem.
    Last edited by a moderator: Apr 25, 2008
  8. Smith333

    Smith333 Member

    Messages:
    107
    Time for another update. I bought a generic Fluidmaster flush valve ($7) from HD and installed that. The water level in the bowl was even lower.

    However, when I removed the Toto-supplied Korky, I noticed that the blue cover had "528" stamped on it, not "528T" like I was expecting.

    Does the 528T have the "T" stamped on it along with the "528"? The stamping is located on the slanted face of the blue cover below the words "ANTI SYPHON".
    Last edited by a moderator: May 3, 2008
  9. Mikey

    Mikey Aspiring Old Fart, EE, computer & networking geek

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    2,714
    Location:
    Central Florida
    Swap the valves between the "good" toilet and the "bad" toilet and see if the problem follows the valve.
  10. Smith333

    Smith333 Member

    Messages:
    107
    I took the plunge and bought a 528T for about $27 with shipping. It is visually identical to the 528 in my Drake with one exception: The inside diameter of the bowl fill outlet on the 528T is 13/64", as opposed to 3/16" in the existing 528.

    In practice, the bowl fill rate increased only marginally over that of the existing 528. The improvement definitely was not worth the added cost.

    I would like to find out what is different with the flush valve of Drake #3, but I have no idea if or when I'll be able to do that (the toilet doesn't belong to me).
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