Who’s a Plumber?

[jagermeister]

Need some insight from any experienced plumbers and/or DIY types.

Working on a 2nd floor remodel right now and I’m laying out a new bathroom. The 3” main sewer vent is conveniently located nearby. However I’m try to figure out my shower and sink venting. The 3” vent exits the roof very close to the soffit, close enough to that there’s not enough space to put in a Wye fitting without coming down from above the rafters first. My dad, who is very handy and has done a lot of plumbing over the years, tells me you can’t have a negative pitch on the vent pipe... so he’s proposing to run a new 2” vent out the roof separately for the shower/sink. But I just don’t understand why??? The whole purpose of the vent is to simply prevent air lock while draining, right? So a negative pitch into the existing 3” vent still allows atmospheric pressure into the drain. Can someone please clear this up for me? I apologize in advance for the crude picture. You get the idea.

 

[xbowguy]

@Hoytmania

If Hoyt don't know...don't mess with it!...LOL

 

[Hoytmania]

Give me a call @jagermeister we'll get things figured out.

 

[hickslawns]

Rick beat me to it.

I'm with your dad. Can't have negative. Think of gravity fed water. It HAS to flow downhill. Or in the case of your vent. . .uphill.

 

[Jackalope]

You can have a negative pitch and expect it to work right. My basement bathroom in our other house had almost this exact configuration. with the exception being it wasn't two 45 bend but rather one 45 on a Y coupler. If memory serves me right the general rule for things like chimneys and exhaust vents is for every 45 degree bend expect a 20% increase in resistance. The more bends required the bigger the pipe needs to be.

 

[Big_Holla]

The only problem I see is the horizontal and negative direction on the vent pipe would be next to impossible to snake if there were ever a blockage. Wasps could love that set-up.

 

[jagermeister]

Thanks for the insight fellas! And @Hoytmania is a huge help in the clutch as usual. I’ll try to remember to update this once we come up with a final solution.

 

[bowhunter1023]

Let the record reflect that one again, from arrow builds to plumbing, TOO has your back.

 

[Quantum673]

You can also add one of those mechanical diaphragm vents (air admittance valve)in the vanity to add venting. That would be in addition to what you have proposed. I would think that would solve it.

 

[Mike]

You can also add one of those mechanical diaphragm vents (air admittance valve)in the vanity to add venting. That would be in addition to what you have proposed. I would think that would solve it.

That's what I would do

 

[jagermeister]

Great tip on the AAV!

 

["J"]

How’s the lifespan on the AAV’s?

 

[Big_Holla]

How’s the lifespan on the AAV’s?

Forgot about those, we have had one under our bathroom sink for over 20 years and still works perfectly. Definitely would know if it wasn't.

 

["J"]

Forgot about those, we have had one under our bathroom sink for over 20 years and still works perfectly. Definitely would know if it wasn't.

We have a few of them, one for the kitchen sink and the master bathroom.... First time having them and was just curious too their lifespan and if any upkeep is needed.

 

[Mike]

We have a few of them, one for the kitchen sink and the master bathroom.... First time having them and was just curious too their lifespan and if any upkeep is needed.

If you smell sewer gas, it's time to replace it.

 

[mike hunt]

What about a loop vent?

 

["J"]

If you smell sewer gas, it's time to replace it.

Yeah, that’s what I figured.... When I first spotted them I was like what kind of Mickey Mouse shit is this