What I'm saying is this guy wants to use a 1 1/2" Vent
for a WC. The WC is 3", you need to replace a 3" water
slug with a equal amount of Air or you create lower
pressure or what many call a vacuum. This makes no sense
unless there is some proof this works. This water first enters
the 3" line pushing air ahead of it then an equal amount of air
must replace the water. Not doing this will upset the +/ - 1"
of atmospheric pressure needed to balance the P traps in the
Hell, why not use a 1/4" vent line ? All you need is an air compressor.
The Code is Law when the word ' Shall ' is in that part.
The Code has allot of ' Mays ' and ' Shoulds ' in it.
May, is to ask permission and Should, means its up to you.
I *would run 3" if I could I'm not cheap on materials, but
no, Mike. 2" before VTR. We know there is far more than
a simple statement saying this. I just say physics says no to 1 1/2".
I have the math, I can post it later.
Air pressure is the most important thing in venting. You must
maintain the +/-1" in P traps for balance.
I say no also due to the cold weather in CO as it could
block the vent in 24 hrs depending on temp.
I say no as a bird could block that small vent for the Lav.
I say no as I would not want to go back and tear out the walls
if they have venting problems.
Its his buisness, he says it will save him money. Ok.
Well OK. The picture you painted was that of a 3" pipe totally filled
with water, and then pulling a perfect vaccum. The water gets all spread
out, and in a stack, it adheres to the sides of the pipe. The way you were
making it sound was that you'd need a 3" vent to replace the air so that the
sink trap would be protected. No wonder I was wondering.
I never meant it that way. Some don't know that fluids *swirl
in a Hoz. line a short distance from initial start point. If in a stack
over 3 floors or 30', fluids stops and equals gravity and a slug
of fluid falls over the stopped slug and all slugs still have 7/24
of Air in its center, this is what makes for the air balance in
the P traps +/- 1". 7/24 is a constant.
So, in a stack; I mean that a 7/24 of 3" is larger than 7/24
of 1 1/2 " So, there is less chance of self siphoning.
In a Hoz. line that goes into a T then a Stack, the fluid will
not hit the opposite side of the inside Stack line. ( gravity conditions)
Providing the Hoz. is equal or less then the Stack size.
So, even here there is air. Its the volume of air to be concerned
about for balance. Size matters.
Just like in, ' Bob's male enhancement ' commercials.
The way these things are figured is to look at the charts in the
applicable code book. They've assigned fixture units for various fixtures.
You look at the load, calculate the appropriate developed length, and see
which size pipe to run. By these figures, for example, if there's a full
bath, you can vent a bathtub with 1.5", vent the toilet with 2", and even
wet vent it with a lav. It works just fine. You tie these vents together
and run them to the vent stack (or stack vent). Now if you want to run 3",
it's OK. I guess you could run 4", but it won't work any better.
Gee, why not just draw a bullseye on your chest?
I think I'll surf over to alt.medicaldoctors and tell them which EEG
machine I like best., or how I think an MRI should be done.
Now go back to one of your wives and repent.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.