Vented SVP question

[OIC]

Having searched everywhere without an answer I found this forum. Looking for advice.

I have an old toilet on the top floor (to be removed) which empties into an outdoor vertical SVP and into the ground. The pipe is straight with a vent terminal on top.
Another toilet on the ground floor empties through the suspended timber floor into (what I suspect) a drain.

I wish to create internal vertical SVP going through the floors at the corner of the house from underneath and vent it through the outdoor SVP via loft, removing the upstairs toilet. However, in order to do so the 110mm pipe will have to go to the ceiling of the top floor into the loft and then connect to the new stack in the loft.

The entire drainage will be through the new indoor soil stack into the underground drain in the foundation of the house. For the air, the stack will then go through into the loft, come back down from the loft to the position of old toilet, get out through the wall into external stack where nothing else is connected except the outside vent terminal.

Will that work? Is it allowed?

 

[Madrab]

Never seen or implemented a downward leg in the SVP like you propose. As long as there is no part of that stack wet, anywhere on that section then it probably would be ok, if not just a really weird design idea and not per standards. If it's open vent though, rain water/condensate may gather in the lower section of the pipe which is not recommended.

I recommend having another think about the desired path.

 

[OIC]

Thanks Rob,

That is a good point, do you mean the rain water and condensation will collect in the inclined pipe that was connecting to the old toilet? Because the low section of the old pipe is still connected to the drain as before...

 

[Hugh Jaleak]

If you're leaving original SVP in situ, just cap off the WC connection and retain that as a vent. Cap new stack with an Air Admittance Valve. No need whatsoever to join the 2.

 

[OIC]

And if durgo valve is not a viable solution?

 

[Hugh Jaleak]

And if durgo valve is not a viable solution?

Why would it not be?

 

[OIC]

Why would it not be?

There are design considerations. If I put durgo on new SVP stack, it will have to be in the main staircase at 3.5m height from the steps... and in the loft because of insulation wanted to put the pipe under

 

[Madrab]

It seems the design is in danger of becoming a little convoluted? Nothing wrong with fitting the durgo above the insulation line in the loft. It won't affect the efficiency of the insulation of you have it tight to the pipe.

 

[thomp1983]

Why would it not be?

Not doubting your knowledge Hugh but wouldn't he have to check at least one other property on his drain run is vented?

I'm about to fit a svp for a new bathroom, there's 6 houses attached to our drain, 5 of the svp's have durgos so the building inspector has said I have to have mine vented, which for me isn't an issue due to where it'll be.

 

[Madrab]

wouldn't he have to check at least one other property on his drain run is vented?

If you're leaving original SVP in situ, just cap off the WC connection and retain that as a vent

 

[thomp1983]

Sorry missed that bit

 

[Hugh Jaleak]

Thanks Madrab. Just seems complete overkill to try and join new stack to old in the manner described!

 

[Madrab]

Just seems complete overkill to try and join new stack to old in the manner described

For sure Hugh and TBH and I think I kinda had a 'couldn't see the woods for the trees' moment there. I think it was the mention that the new stack was to be the main and then remove the old external stack ..... but keep the top end to vent the new one . Now as I write that, that sounds even stranger

 

[Hugh Jaleak]

Post #3 the OP says "Because the low section of the old pipe is still connected to the drain as before...". So just leave it there, disconnect the WC and cap off. Job done!