wrote in message
oups.com...
No the sewer venting is not a problem. Please read up on this type of
problem before posting your opinion as fact. Try reading up on a "suds
control zone."

Excessive suds cause exactly this problem. Sorry dude.


OK I did a little reading,

===========begin quote===========================
Code Questions
Question: We have noticed that some plumbing codes have suds zone
requirements while others do not. Which code is correct?

Julius replies: The plumbing code with the suds zone has the older code
requirements. The plumbing codes that have more recently evaluated the suds
zone requirements have eliminated the code section. Hence, suds zones are
not effective.

There have been a lot of studies done on sudsing in a drainage stack in tall
buildings. Suds are caused by a combination of turbulent action, air and
high sudsing detergents. If you eliminate one, you have eliminated the
development of suds in the stack. If you study the design layout recommended
for a suds pressure zone, the layout does nothing to eliminate any of these
three items.

The suds zone concept was based on delaying the suds entering the drainage
stack. There was nothing in the suds zone to eliminate sudsing. Once the
suds zone filled with suds, the suds then entered the drainage stack.

The current theory of suds prevention is the use of low sudsing detergents
and smooth pattern fittings. One of the problems, however, is we have no
control over the types of detergents sold on the retail level. Hence, the
sizing of the drainage stack and the proper use of fittings is very
important.

Another means of reducing the creation of suds is by having a drainage stack
discharge into a larger diameter building drain. In other words, a 3-inch
stack discharging into a 4-inch building drain.

===========end quote====================

Seems to me it might be more accurate to state that since the plumbing is
flawed (my point) using a low sudsing detergent is necessary (your point).

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.