Question about toilet vent in regards to flow.

[JSA112233]

Two questions really. First is prolly simple but since im new to plumbing really i would like to confirm. Does the vent for the toilet need to be in "front" of it or "behind" it. I ask this simple question because the toilet really cant pull air if the vent is in front of the toilet flow right? Or, does it even matter. I describe what im talking about in this picture. I also attach an illustration of my current setup to see if there would be an issues.

Image One: https://gyazo.com/3d12535f7b060f7211faef6de5de6219

Image Two: https://gyazo.com/ed10806099404bd704b10abcd5839165

 

[James Henry]

It doesn't matter if it's in front or behind. Your drawing needs more details for anyone to comment. Walls etc.

 

[Sponsor]

 

[Reach4]

Toilets are different than other things. The trap of a toilet is in the toilet. Unlike other traps, you want that to siphon out. Then there is a refill tube that refills the trap.

 

[hj]

In drawing #2, your Toilet #1 is technically NOT vented, because the flow from toilet #2 goes past its connection, and vent #1 is useless and has no function. In your first drawing it depends on WHAT is connected to the waste going past toilet #1.

 

[Tuttles Revenge]

That is almost a circuit vented system. But each fixture needs to tie into the horizontal run separately rather than as HJ describes and the picture 2 shows the waste running thru the toilet fitting.

UPC code allows circuit venting as illustrated here. The vents for the most upstream toilet are downstream of the toilet, but upstream of all other subsequent toilets to a point (which you won't achieve in a house)
https://www.kingcounty.gov/depts/he...ocuments/plumbing/horizontal-wet-venting.ashx

 

[Reach4]

Michigan uses IPC. UPC is more restrictive and conventional.

Why does a toilet need a vent? There are two questions there IMO. What are the code requirements, and what are the principles of what makes the toilet and plumbing around it work well.

I am not a plumber. Functionally, I think to make the toilet flush well, you want the slug of water to not be impeded by backpressure. The toilet will get the incoming air it needs for the flush from the bathroom air. You also don't want the slug of water to cause problems for other fixtures. There needs to be a roof vent in the system.

The codes define ways that those functions can be achieved by prescribing and forbidding some things.

 

[JSA112233]

Thanks to everyone who has replied. I will be taking some pictures of the buildings plumbing that is in question and updating this post in the future.

 

[hj]

Turtles:
One comment regarding the drawings you showed. In #5, if the proper fittings are used the note about the lavatory connecting horizontally, (and I have no idea why that is even a consideration), that fitting WOULD be Y-1/8 bend AS REQUIRED, installed horizontally, not a T on its back, (it depends on how you interpret the isometric. Sort of like looking at the photo and either seeing a young girl or an old lady).

 

[JSA112233]

Just because i feel i left a HUGE part of the plumbing diagram out im going to post the full one showing all the vents and branches off the mainline. Maybe this will change the verdict. Is vent #1 still useless? Are the toilets going to be fine or do i need to install a vent somewhere else.

Updated Image: https://gyazo.com/66a7e4840759e776a22912073cecb3ed

 

[Tuttles Revenge]

Turtles:
One comment regarding the drawings you showed. In #5, if the proper fittings are used the note about the lavatory connecting horizontally, (and I have no idea why that is even a consideration), that fitting WOULD be Y-1/8 bend AS REQUIRED, installed horizontally, not a T on its back, (it depends on how you interpret the isometric. Sort of like looking at the photo and either seeing a young girl or an old lady).

Yeah.. All of those drawing assume we know the proper orientation of fittings but they should be drawn properly.. also it looks like the best software that King County can afford for this is Microsoft Paint! I'll make sure to bring it up the next time im in the chief inspectors office griping about inspectors