# Fresh air inlets



## NYC Plumber (May 4, 2011)

I know the theory, but does anyone think they are really neccasary? I personally think everything would work just fine without them.
Only thing you would miss is sewage spilling out when there is a stoppage....


----------



## TX MECH PLUMBER (May 27, 2011)

What is afresh air inlet??? Maybe we call it different down here Do explain please


----------



## NYC Plumber (May 4, 2011)

Before the house trap its basically a vent that terminates a min 6" above grade. Usally terminates with a perforated plate or return bend.


----------



## TX MECH PLUMBER (May 27, 2011)

We don't have those or house traps they are against code. We have back water valves but those are rare. The main vent in the house vents the city sewer rite ???


----------



## NYC Plumber (May 4, 2011)

Oh, no here it s code to install them.
House traps Protect the building from the sewer.


----------



## TX MECH PLUMBER (May 27, 2011)

NYC Plumber said:


> Oh, no here it s code to install them.
> House traps Protect the building from the sewer.


So is a house trap just a running trap???


----------



## NYC Plumber (May 4, 2011)

TX MECH PLUMBER said:


> So is a house trap just a running trap???


Yeah basically


----------



## incarnatopnh (Feb 1, 2011)

All the old houses with the original clay sewers have house traps here but they are grandfathered no newer sewer has them. Amazing the differences from nyc to upstate ny.


----------



## DesertOkie (Jul 15, 2011)

I think Tucson code called for a vent before a building trap but it had to be pretty tall. For the most part they wanted back water valves. Only time they let us do a building trap was when the pressure from the city sewer was blowing sewer gas back so hard you could smell it on the ground and that's after we raised the vents 6' over the parapit wall. I think it was the citys pump station that was causing the pressure.


----------



## DesertOkie (Jul 15, 2011)

I think NYC has building traps to try and keep the rats out.


----------



## NYC Plumber (May 4, 2011)

DesertOkie said:


> I think NYC has building traps to try and keep the rats out.


I have heard that, but i think its an old wives tale. But maybe, it doesnt hurt...
I think the main reason is to keep sewer gases out of the building.


----------



## NYC Plumber (May 4, 2011)

DesertOkie said:


> I think Tucson code called for a vent before a building trap but it had to be pretty tall. For the most part they wanted back water valves. Only time they let us do a building trap was when the pressure from the city sewer was blowing sewer gas back so hard you could smell it on the ground and that's after we raised the vents 6' over the parapit wall. I think it was the citys pump station that was causing the pressure.


Who makes the descion?


----------



## U666A (Dec 11, 2010)

NYC Plumber said:


> I have heard that, but i think its an old wives tale. But maybe, it doesnt hurt...
> I think the main reason is to keep sewer gases out of the building.


My old man's house has 3 floor drains in the basement (I know, excessive right?) of his home circa 1895 without traps. He has a building trap. Possible cost savings?

You could argue that the main stack vents the building trap, but it would be a big wet vent right? Well, if a wc forms part of a wv, it must be the most downstream fixture. So even if the wc is tied in immediately upstream of the bt, I don't think this code would be satisfied (I know that the bt is not technically a fixture, but you know what I'm getting at).

So to answer the original question, a FAI is a separate vent for the building trap, and in my opinion, necessary.


----------



## DesertOkie (Jul 15, 2011)

For that one it was a city engineer and the architect of the building (Cluster F) but it was a city health clinic so every thing we did had to go through the engineer. I think the UPC called for a vent on building traps. We did not put them in per the dynamic duo, it was in a parking lot. We did put the traps as close as we could to the building I think thats different then most building traps.


----------



## NYC Plumber (May 4, 2011)

U666A said:


> My old man's house has 3 floor drains in the basement (I know, excessive right?) of his home circa 1895 without traps. He has a building trap. Possible cost savings?
> 
> You could argue that the main stack vents the building trap, but it would be a big wet vent right? Well, if a wc forms part of a wv, it must be the most downstream fixture. So even if the wc is tied in immediately upstream of the bt, I don't think this code would be satisfied (I know that the bt is not technically a fixture, but you know what I'm getting at).
> 
> So to answer the original question, a FAI is a separate vent for the building trap, and in my opinion, necessary.


I know what your saying but... I dont think a house trap would syphon out very easily, and the seal is constantly being replenished every time a fixture is used obviously. Idk just seems overkill to me. What can happen if you installed a house trap without the fresh air?


----------



## DesertOkie (Jul 15, 2011)

Do you guys have a premade trap for the building traps or is it a couple of 45s?


----------



## NYC Plumber (May 4, 2011)

DesertOkie said:


> Do you guys have a premade trap for the building traps or is it a couple of 45s?


yeah its basically just another fitting, like a running trap only has handholes which are basically co plugs so you clean it out.
Actually new code here says, you cannot make a house trap with fittings, it has to be one piece.


----------



## PLUMBER_BILL (Oct 23, 2009)

NYC Plumber said:


> I know what your saying but... I dont think a house trap would syphon out very easily, and the seal is constantly being replenished every time a fixture is used obviously. Idk just seems overkill to me. What can happen if you installed a house trap without the fresh air?


*Simple no upstream toilet would flush properly if at all. Granted the vents on the roof act as chimney's' drawing fresh air into the building drain and vent system. Thereby ventilating the indvidule system not the whole sewer like areas not allowing the main trap [house trap]. But lets look at it backwards [when it is not an inlet] picture the trap with a 4" seal and a body of water coming down the pipe. The air between the 2 bodies of water must be removed hense the fresh air inlet working in reverse. *


----------



## NYC Plumber (May 4, 2011)

PLUMBER_BILL said:


> Simple no upstream toilet would flush properly if at all. Granted the vents on the roof act as chimney's' drawing fresh air into the building drain and vent system. Thereby ventilating the indvidule system not the whole sewer like areas not allowing the main trap [house trap]. But lets look at it backwards [when it is not an inlet] picture the trap with a 4" seal and a body of water coming down the pipe. The air between the 2 bodies of water must be removed hense the fresh air inlet working in reverse.


Ok, but the water in the pipe approaching the trap is not full, so there is still room for air to move.
I know what you mean i am just being devils advocate.


----------



## PLUMBER_BILL (Oct 23, 2009)

NYC Plumber said:


> Ok, but the water in the pipe approaching the trap is not full, so there is still room for air to move.
> I know what you mean i am just being devils advocate.


*Granted, but suppose a couple were flushed within seconds of each other. In residential plumbing 2 & 1/2 baths would only need 3" piping. But here 4" trap and 4" building sewer. *


----------



## NYC Plumber (May 4, 2011)

PLUMBER_BILL said:


> Granted, but suppose a couple were flushed within seconds of each other. In residential plumbing 2 & 1/2 baths would only need 3" piping. But here 4" trap and 4" building sewer.


Thats a good point. But what would happen, i guess drain slowly? Maybe cause a stoppage? Your right tho u should design for worst case...


----------



## NYC Plumber (May 4, 2011)

I would also think in a house it is much less important. In a commercial bldg or high rise residential you would have much more pressure fluctuations obviously.


----------



## cityplumbing (Jun 12, 2010)

DesertOkie said:


> I think NYC has building traps to try and keep the rats out.


 
I have actually pulled three rats out of the same building house trap with an auger a while back it was nasty:thumbup:.


----------



## NYC Plumber (May 4, 2011)

cityplumbing said:


> I have actually pulled three rats out of the same building house trap with an auger a while back it was nasty:thumbup:.


Wow.. Where?


----------



## cityplumbing (Jun 12, 2010)

I have found that house traps are bad for the homeowner Causing grease to not pass the second cleanout plug on the trap, hardening up causing a stoppage. Its good for us when we get a service call out of it just pop the cleanout plug and clear it with a screw driver...


----------



## cityplumbing (Jun 12, 2010)

NYC Plumber said:


> Wow.. Where?


Staten Island NY


----------



## Redwood (Sep 8, 2008)

NYC Plumber said:


> I have heard that, but i think its an old wives tale. But maybe, it doesnt hurt...
> I think the main reason is to keep sewer gases out of the building.


Close!
With the building density that you have in NYC if you didn't have house traps you might as well have open sewers with all those vents through the roof sewer gassing the neighborhood....

The sewer gases would be stopped by the traps on the fixtures. The house trap keeps the gases out of the neighborhood... :yes:


----------



## NYC Plumber (May 4, 2011)

Redwood said:


> Close!
> With the building density that you have in NYC if you didn't have house traps you might as well have open sewers with all those vents through the roof sewer gassing the neighborhood....
> 
> The sewer gases would be stopped by the traps on the fixtures. The house trap keeps the gases out of the neighborhood... :yes:


Good point. I never even thought of it to that extent.


----------

