main sewer line ???

[camaro77]

got to cut out a main P trap in my house for the main sewer line and I plan on using PVC in place of the cast trap. I have a 4 inch cast main vent on the house side of the trap now my question is does the vent need to go back the plumbing is all new and updated in the house with traps on all the sinks and tubs and toilets and a vent all the way up to the roof. also can I use just sch 40 white PVC or does it need to be the green sewer PVC? this will be getting back filled and buried once the job is completed.

Thanks Jeff

 

[The FIB]

I would think local codes would decide what would be acceptable, I never heard of a P-trap on the main sewer line. The cast Iron is really heavy stuff, make sure it is well supported when cutting anything in the house. I heard a story of a guy who cut a section out in his basement pipe causing the riser to drop a little, causing nearly every joint in the system to leak.

 

[The Cobbler]

you need to check your municipality for the code... here, building traps were obsolete many years ago .

 

[Jim greengo]

Pictures?

 

[camaro77]

you need to check your municipality for the code... here, building traps were obsolete many years ago .

the house was built in 1963 and my understanding is that was the way it was done back then

 

[Jim greengo]

Rat problems?

 

[SALIV8]

Also never heard of a main sewer line Ptrap, but if it were me I would replace what is there with a min of sch 80 pvc if it's currently cast.

Disclosure- I am not a licensed plumber.

 

[Jim greengo]

Sch 40 PVC is fine for residential plumbing.

 

[75gmck25]

There are different types of Fernco couplings, and the one you want has the rubber to seal against the pipe, and a wide metal band to compress around the cast iron and PVC pipe and provide support. Once you get it in place and tight, you then want to support the pipe joint from underneath with something that will not compress and let the joint move when you pour cement on top.

I just used some bricks and sand under the joint, but some folks recommended pouring dry cement mix in around the pipes and then pouring water on it to form a bridge/support. I'm not sure if that would work better.

Bruce

 

[Jim greengo]

There are different types of Fernco couplings, and the one you want has the rubber to seal against the pipe, and a wide metal band to compress around the cast iron and PVC pipe and provide support. Once you get it in place and tight, you then want to support the pipe joint from underneath with something that will not compress and let the joint move when you pour cement on top.

I just used some bricks and sand under the joint, but some folks recommended pouring dry cement mix in around the pipes and then pouring water on it to form a bridge/support. I'm not sure if that would work better.

Bruce

no nub coupling.

 

[BD1]

no nub coupling.

Above hit wrong key, NO HUB COUPLING.

 

[tfb]

If you are talking about the curb trap, the vents on these are usually sealed now because your municipality does not want to treat storm water which can enter the sanitary system thru the vent.

However it isn't a bad idea to install the vent because it give you a great access point to clear a blockage from outside the building. Plus it allows you to assess exactly where a blockage is located.

It creates a water seal, (trap) between the main sewer and your house drain and prevents travel from the main to your lateral line.


https://www.beatlas.com/details/1600SV412

 

[Itsjustdirt]

Why trap a main sewer line? Honestly curious.

 

[bczygan]

Why trap a main sewer line? Honestly curious.

Like any trap, it keeps out sewer gases.

We have them in our circa 1940 houses here in Detroit.

Bill

 

[6768rogues]

It sounds as though you are talking about a whole house trap. They are typically not used in our part of the country, but I have seen one occasionally. In codes that recognize them, they do need a fresh air inlet upstream of the trap but close to the trap. That vent usually just goes through the wall higher than the trap to outdoors, not all the way up through the roof. If your local code no longer requires the trap, simply eliminate it.
Schedule 40 PVC will do a great job.

 

[Lynden]

Fernco no hub couplings -- cast iron to plastic...

https://www.fernco.com/specifications/pipe-material/cast-iron-connecting-to-plastic

 

[kbs2244]

Get rid of it.
Any sewer gas will vent through the house and out your roof.

 

[GTO]

I would think local codes would decide what would be acceptable, I never heard of a P-trap on the main sewer line. The cast Iron is really heavy stuff, make sure it is well supported when cutting anything in the house. I heard a story of a guy who cut a section out in his basement pipe causing the riser to drop a little, causing nearly every joint in the system to leak.

Years ago(long time ago) before they required traps under every sink and tub/shower,they put the traps in the main line..
Very common in older areas.Very old

 

[theoldwizard1]

you need to check your municipality for the code... here, building traps were obsolete many years ago .

Roger that !

Get rid of it if you are allowed to !!