Browse Forums Building Standards; Getting It Right! 1 May 20, 2009 1:37 am Hi All, My house has a quite a large stink pipe (I think they are called educt vents) and due to a couple of previous renovations, it now has a couple of 45 degree joins between the concrete and the eaves. I recently had a builder out who gave me a hand with some patio plans and he noticed it and said the diameter of the pipe was overkill. It is at least 100mm. He reckons that they only need to be 40mm. Can anyone confirm this? Also, the pipe extends around 2 meters above the roof tiles. We are going to be doing a fair bit of work in that area in the weeks to come, and if I could reduce the size of the pipe to 40mm as well as make it travel in a straight line, then I'd be really happy. Any thoughts are much appreciated. Regards, Chris Re: Educt vent/stink pipe size 2May 20, 2009 8:47 am Depends on what it is venting... Is it venting toilet connections or other bathroom connections? Electrical Engineer... Don't hold that against me... And keen owner builder... Mainly the building part!! Re: Educt vent/stink pipe size 4May 21, 2009 2:18 pm Doesn't say much really... Is it black water then from the kitchen only? How many vent pipes does your house have? Electrical Engineer... Don't hold that against me... And keen owner builder... Mainly the building part!! Re: Educt vent/stink pipe size 5May 21, 2009 6:36 pm 50 mill DWV is all thats required today on an educt vent. And you can terminate it 450mm above the roof, but that depends on the steepness of your roof and if theres any buildings very close by that tower over yours. In days gone by, all drainage fixtures needed vents. That was known as the Fully Vented System. after some time, the Partially Vented system was introduced which cut down on the amount of vent pipes needed, then in the 60s the Unvented System was introduced, where the only vent needed is the educt vent, which is placed between the last and second last fixture. Educt vents were still 100mill until the 70s when the size was revised and on the average domestic house, 50mm was judged to be adaquate for all vent pipes. The only other vents required on house drainage systems are on stack pipes and overlength branch lines. And in areas where there is a boundary trap, it will will be vented but through a mica flap vent just above ground level. Sometimes its not worth replacing 100mill vent pipes with 50mm pipes, because it will leave a large hole in the eaves. rather than leave a gaping hole that needs to be repaired, its better to replace a rusted pipe with 100 dwv pvc. The purpose of vent pipes is to ensure a balanced air pressure in the house drainage lines. without a vent pipe the drains would syphon the water seals in the traps and the drainage lines wouldnt function correctly. Re: Educt vent/stink pipe size 6May 26, 2009 1:28 am Hi again, Thanks heaps for the info. Very informative indeed. I am not sure how to tell which is the last and second last fixture (and what designates a fixture), but I do know that our house was built in the mid 70's. The current vent is 100mm PVC, and was "adjusted" about 10 years ago by the previous owner as they had some louvred windows put in and the pipe was in the way of them opening. This is why it now has a few 45 degree joins in it. Changing it to a 50mm pipe that could run flush with the wall would be ideal, as the current 100mm pipe sits in a corner about 300mm from one wall, and 100mm from another. It just leaves a really awkward space around this pipe and it's visible from a couple of different windows. We are about to embark on a lot of work in the area, with a new patio and re-paving the entire area as well. Therefore a couple extra holes in the eaves will be OK by us. Thanks again for the replies. Chris How do you remove one of these ceiling air con vents? And is it possible to disconnect the duct joined to the vent from inside the house, without going into the roof cavity? 0 4038 OK it's been a little while! I've been busy getting time where I can to work on this. I started by grading a pad (borrowing a… 26 17378 yep sounds good make the footing bigger to to allow for the pipe in the middle 3 5288 |