Toto WT151 wall carrier with AP CT426WTG

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British Columbia
I roughed in the WT152 wall carriers. I didn't bother to order the other pieces.

When I went to order the wall toilet it turned out the WT152 had been discontinued and the wall toilets were no longer available. After talking to toto tech support they concluded that I could use the new wall toilets if I swapped out the toto wall carrier flush valve to the THU729.

I pulled the old flush valve and compared it to the new flush valve. The valves appear identical except the old one has a vertical plastic piece that allows the flush valve to adjust between 9 / 6 and 4.5 L. The default on the 152 was 6L = 1.6GPF. The new one didn't have the plastic piece which would seem to indicate a 9L = 1.97L fill.

The difference between the WT152 and WT172 is supposed to be 1.6 and .9 GPF vs 1.28 and .9 GPF. Now the issue is that the old toilets could handle more water. The new wall mount toilet handles less water and without changing the volume could cause splash out.

Swapping out the flush valve to use 9L instead of default 6L doesn't seem to make sense to me but it is possible I don't understand how the flush valve is working. I've played with it and the vertical bar seems to cover holes. Setting to 9L has all 3 holes open. Setting to 6L has the lowest hole and the non coverable hole open. Setting to 4.5L has the upper hole open and the default hole open. This seems to make sense. The lower holes will allow more water to flow into the flush valve.

Now I've put the AP bowl - CT426CWG - onto the carrier with the swapped out flush value that is set to what I think is 9L. I've flushed it a few times and I get a few maybe 3 drops of water ejected from the bowl onto the floor or onto the deck of the toilet ( no seat yet ). I am not sure the 3 drops of water would be a deal breaker anyway you slice the cake anyway.

I think the correct thing to do here is to adjust the flush valve so that it only fills to the 4.5L then the max that can come into the bowl is the 1.28 gallons. I also think either the flush valve is a red herring and should be set to 4.5L and I shouldn't have had to swap it. Maybe the new one was just missing the stupid vertical bar and is the same part? The spec sheets for the WT152 and WT172 do list them as different parts though.

Anyone else have to do this? I have three of these things that I need to adjust.

Also the 152 carrier has a 1/2" FPT, I was thinking of using a 1/2" close nipple and then trying to find a 1/2" FPT shutoff that could hook to the FPT washlet ( SW3084 ) instead of going with the toto specific THU468. Anyone go this route?

If you've read this far - thank you !
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