Toilet Sucking Air/water

Wondering if anybody could shed some light on a three year old investment property suddenly sucking air and water when flushing and occasionally overfilling? We have had two plumbers come out CCTV the lines confirmed they are clear, installed a new toilet and also additional vent under the vanity - same issue. It has cost us a lot in repairs and still unable to identify the problem.
Builder says its non structure so wont cover under warranty.

Overfilling the cistern do you mean? That is a float level issue.

How can it suck air when flushing? Are you saying that the water level in the bowl falls too low? If so, that is a venting issue. If it wasn't a recent problem and has occured from new, I would suggest looking at the trap's volumetrics.

How would installing a new toilet (I assume bowl) possibly fix the issue? Some plumbers!

Where was the bowl manufactured? Is it Australian? If so, you should pose the questions to them. If they have a good R&D department, they should love getting their teeth into it.

how do I upload a video?

by any chance is it a Parisi toilet? I am experiencing the same thing and my plumber hasnt been able to come up with an answer, Will keep investigating and post if I find a solution

Would be great if you could let me know.
No it is not the same toilet. So frustrating, a lot of people say a venting issue so why hasn't the AAV vent installed fixed the issue.

leave it me me, ill find out. my wife is giving me hard time about it

It could be a few things. You may have an improperly vented system or you may have a clog further down the line. When that suddenly drains, it may create a vacuum that sucks the water out of the toilet. Either can cause this to happen depending on the exact layout of your toilet, shower, vanity vents, pipes etc. I doubt whether a specific brand of toilet would cause this although some of the newer ones use a lot less water to flush than older ones.
Are all your other connections working as they should? Check that all your floor wastes have water in them too.

Stewie

i think your right, i am getting another plumber out tomorrow

the ensuite toilet is working perfectly only the main toilet which is located towards the back of the house has the issues. One plumber mentioned that the house only has one vent and it is located more then 10 metres away when taking into account the bends in the pipe. An AAV vent was installed under the vanity however does not seem to help, I thought the AAV would fix it even if the main vent pipe is located just over 10m.

Something has changed and it can only be the existing vent or the pipe system which was examined by CCTV.

First priority should have been to check the vent pipe, this is quick and easy to do. Did they do this?

When both plumbers said they CCTV the pipes, I am assuming so. Does the camera have the capability to go up the vent pipe to check? I actually should double check with them.

If there are multiple fittings sharing the same vent then the toilet needs to be the last connected to the vent.This simple fact is sometimes lost on some tradies. It also needs to be within a certain distance from the vent which from memory is only 2m or less ( I may be wrong on this and any plumber can correct me ). I know you have installed the AAV but I'm wondering if this is not doing its job properly. 10m away to the main vent also indicates to me a poorly planned plumbing system. I maybe wouldn't be blaming the original plumber for this as sometimes the owner or builder insist on where the main vent is located because of aesthetics not practicality.

Stewie

This may be of some relevance http://www.fairtrading.nsw.gov.au/__dat ... valves.pdf

Stewie

NO!

Also, the plumber who installed the new toilet was a shonk.

It's common in plumbing, particularly with roof drainage. I refer to the practice as aesthetics subjugating function.

you are correct, one plumber confirmed vent pipe wasn't checked. What is the easiest way for me to do this myself? put a hose down the vent pipe and flush with water ?
Originally set of tenants has no issues with the toilet in 3 years. The new tenant might now be using the toilet more often and hence why it has now become an issue.

Does the toilet flush slowly in part and does it (even sometimes) make a gurgling sound?

There will be plenty of videos on YouTube that explain how vent pipes work and how to identify a blocked vent although yours, if applicable, will be a partial blockage.

The video I have linked explains it pretty well and has even included the importance of having someone else inside when you flush the vent.

https://www.youtube.com/watch?v=q1uqqBnx0-Q

Checking the vent should be the first step because something has changed to create your current issue.

Good luck and be careful with the ladder and getting up on the roof.

Thanks for your replies.

Thanks for your replies. I will post a resolution when I finally get one