[Greenbuilding] 2" drain line for a 0.8gpf toilet?

[Reuben Deumling]

Except that carriage distance is inversely related to pipe diameter at low
flow rates. That's the whole point.
Under the conditions I'm interested in, a larger pipe works against the
goal we're discussing here, which is why the 0.8gpf toilets mated with a 4"
pipe performed so disastrously. My question to the designers of that study
and to anyone here is why they didn't consider testing with a 2" line?

On Sun, Apr 24, 2016 at 4:47 PM, Joe Killian <kaa-ajk at sonic.net> wrote:

> Reuben,
>   The American standard Cadet 3 toilet (a popular and very good unit) has
> for it's exit aperture:
> "Fully-glazed 2-1/8" trapway with 2" ball pass"
>   If there's a stoppage anywhere, you'd want it to be AT the toilet, not
> somewhere down the pipe.  So a pipe substantially larger than the fixture's
> exit aperture would be advisable.
>
>   With a macerater, a 2" pipe is acceptable, afaik.  ...If you wanted to
> trade that complication for the smaller pipe.
> Joe
>
>
> On 4/24/2016 3:29 PM, Reuben Deumling wrote:
>
>> I have long wondered whether or when anyone would dare diverge from the
>> 3" standard drainline diameter as we get toilets that use less and less
>> water per flush.
>> Interpolating from this chart:
>> http://www.mpwmd.net/rules/Apr2008/pdfs/RegII/rule24_table1.pdf
>> I see that in terms of fixture units, a 0.8gpf toilet is now at 1, which
>> puts it comfortably within the same class as sinks, which as we know do not
>> require anywhere near a 3" drainline. So..... does anyone on this list know
>> if there is any movement toward allowing a 2" drainline for a 0.8gpf
>> toilet? Or whether there's been any testing of this configuration?
>>
>
>
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