Saniplus, venting a rear flush toilet?

[SoreThumbs]

I'm installing a self standing rear flush toilet in a basement. The toilet will empty into a macerating ejector system (Saniflo or equivalent). The question is about venting. I know that the Saniflo vessel needs to be vented to atmosphere. The question is, does the toilet itself need a fixture vent?

I'm not sure how this would even be possible as the toilet trap arm coming off the back of the toilet is only about 12" or less.

 

[Reach4]

I can't speak to the code, but IMO a vent for that toilet should not be required. I am not a plumber.

 

[Sponsor]

 

[Terry]

The Saniflo toilet just plugs in. This is an entirely different way of doing a toilet install.
Regularly you would be venting a toilet, but not this one.

https://www.saniflo.com/en/installing-a-toilet/73-saniplus.html

 

[Marlinman]

But the macerator does need to be vented. No AAV will work. Go to Terry's link and look at the instruction manual.

 

[SoreThumbs]

Thank you for your replies. This reaffirms for me that a fixture vent is not needed for a toilet in this situation. Perfect.

However, this brings up another issue/question. If a toilet does not need a fixture vent with a Saniflo system, then why does a lavatory vessel or a shower need one? I mean if the toilet can properly function without a vent, why can't a sink? I'm not asking from a code standpoint, but rather about proper function of the system. I'm really curious about this - hoping someone can answer it.

 

[Reach4]

However, this brings up another issue/question. If a toilet does not need a fixture vent with a Saniflo system, then why does a lavatory vessel or a shower need one? I mean if the toilet can properly drain without a vent, why can't a sink? I'm not asking from a code standpoint, but rather about proper function of the system. I'm really curious about this - hoping someone can answer it.

Toilets are special. For a sink, the vent prevents the trap water from siphoning out. A toilet siphons on purpose, and then has a refill tube to refill the trap. The trap is part of the toilet.

 

[SoreThumbs]

That's not my understanding of basic plumbing. Maybe I'm wrong, but a vent preforms the same function on a toilet as is does on any other fixture. The trap being contained within the fixture and a siphon upon flushing has no bearing upon this. What if I has asked about a residential flushing urinal? That contains an integral trap and siphons, does that need a fixture vent on a saniflo system from a functional perspective?

 

[Reach4]

That's not my understanding of basic plumbing. Maybe I'm wrong, but a vent preforms the same function on a toilet as is does on any other fixture. The trap being contained within the fixture and a siphon upon flushing has no bearing upon this. What if I has asked about a residential flushing urinal? That contains an integral trap and siphons, does that need a fixture vent on a saniflo system from a functional perspective?

I concede that a urinal is in the same category, so in that regard, the flush toilet is not truly unique. Perhaps I should say that the toilet is unique in the fixtures normally found in houses. I have thought that a residential urinal would be useful in some houses, but I have never seen one. Have you?

I think you are quite wrong about the thing you thought you might be wrong about.

 

[SoreThumbs]

I'm hoping to install a urinal in my basement workshop next month. That will be one. It will be on a saniflo system. I actually may use an above ground sewage ejector vessel with a gray water pump. Still not sure on this as generic saniflo systems are now available that push the price below that of a gray water system. Anyway, this has morphed into a urinal discussion. I guess we''ll have to agree to disagree about the function and necessity of a vent on a toilet in a normal install.
Are you saying that when the saniflo system runs (pumps) it will not pull negative pressure upon the toilet trap but it will upon the sink trap? How is that possible? Furthermore, what makes saniflo unique in that any other sewage ejector system requires a toilet vent but saniflo does not?

 

[Reach4]

Are you saying that when the saniflo system runs (pumps) it will not pull negative pressure upon the toilet trap but it will upon the sink trap?

No. I am saying that the vent for the saniflow system vent will keep the pressure near atmosphere.

The sink trap vent is needed to break the vacuum of its own flow. Without that vent, you have an S-trap, which, in theory, could be siphoned dry.

 

[SoreThumbs]

Thank you, I was focusing so heavily upon the saniflo vessel itself that I failed to see this point.
So the saniflo vessel vent is acting as the vent for the toilet, got it. Can the saniflo vessel vent also act as the vent for the sink IF the sink trap arm does not exceed it's maximum length of 2.5 feet (1.25" pipe) before entering the vessel?

 

[Terry]

The sink or lav will need it's own vent.