PVC Vent Pipe Mod Question

[Hermes1]

I am getting ready to install a compost toilet in our rig and it requires venting to the outside. I have a couple options to accomplish this, but the most attractive one to me involves taping into the PVC gray water tank vent which resides in the wall behind the toilet. To install a T-connection midstream of the pipe, I will have to cut it, sufficiently to install the T. My question is since I have never removed a vent cap, is the top of the PVC pipe in any way connected to the roof, or is it free to move some? I am asking because if I go this route and cut the pipe to fit the T-connection, I imagine I will have to push the pipe up a few inches (obviously removing the vent cap first) to seat the T-connection in place. Thanks.

[Gdetrailer]

Hermes1 wrote:
I am getting ready to install a compost toilet in our rig and it requires venting to the outside. I have a couple options to accomplish this, but the most attractive one to me involves taping into the PVC gray water tank vent which resides in the wall behind the toilet. To install a T-connection midstream of the pipe, I will have to cut it, sufficiently to install the T. My question is since I have never removed a vent cap, is the top of the PVC pipe in any way connected to the roof, or is it free to move some? I am asking because if I go this route and cut the pipe to fit the T-connection, I imagine I will have to push the pipe up a few inches (obviously removing the vent cap first) to seat the T-connection in place. Thanks.

Hmm.. You might wish to double check to see if that IS the "grey" tank vent..

Seams to me, most of those composting toilets have some sort of POWERED VENTING SYSTEM (IE FAN)..

If that is the case then using the grey tank vent you will now slightly pressurize the grey water plumbing!! :E

The results would be down right ugly..

You would be better ahead to connect to the BLACK tank vent provided no other fixture has any connection to the black water tank (some RVs plumbed the bathroom sink into the black tanks)..

[JoeH]

Hermes1 wrote:

Chris Bryant wrote:
It's free to move.

Thank you.

The vent caps on our MH are screwed to the roof and covered with Dicor self leveling sealant.

[byronlj]

I agree with the femco couplers. I've always called them no-hub adapters.
Dave

[ScottG]

I don't think your pipes are PVC. If they're black then they're ABS.
Only important if you need to glue them.

[Hermes1]

Chris Bryant wrote:
It's free to move.

Thank you.

[myredracer]

What about using a Fernco coupling? They're designed for situations like that, providing you can get it in there and be able to tighten it up.

[Chris_Bryant]

It's free to move.