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

[John Salmen]

I can echo Joe on this and the cadet is a good design as it has restricted
flow to provide a scouring action - and that said oversizing pipe can be a
problem for the same reasons - but current designs are based on 3" and
perform well and that is where I would want to sit 'so to speak'.

-----Original Message-----
From: Greenbuilding [mailto:greenbuilding-bounces at lists.bioenergylists.org]
On Behalf Of Joe Killian
Sent: April-24-16 4:47 PM
To: greenbuilding at lists.bioenergylists.org
Subject: Re: [Greenbuilding] 2" drain line for a 0.8gpf toilet?

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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