On Wed, 01 Sep 2010 15:24:59 -0500, dpb wrote:

TN wrote:
I've got 3 of the same toilets installed in the house I built in 2005.
One toilet has me totally freaked out. It doesn't flush properly and
has gotten somewhat worse over time. I can hold the flush handle down
and the flapper opens just fine. The tank is filled with water and it
empties at rate similar to the other toilets. The bowl just fills up
with water the whirlpool starts but it acts as if it is slightly
plugged. It flushes a little and the waste eventually goes down, but
never the normal "empty the bowl" flushes I see in the other toilets.
I've plunged it before so I know there is no clog.

Does anyone have some advice on how to debug this? My instinct says
the bowl was just casted defective. I can't imaging its a larger plug
somewhere else because all the other drains in the bathroom work fine.

If it's always been a problem I'd suspect lack of near enough or large
enough venting or simply a poorly laid out drain line path that while it
isn't blocked it does add flow restriction in the path. An example
could be a 90-ell instead of sweep in a horizontal run or this is the
last on a longer nearly horizontal run or somesuch...

Gotta have a long enough vertical drop after the flange for the siphon to
build up enough suction to pull turds and tissue down. Especially with
today's low-flow bowls.