Purpose of Toilet Vents / Positioning ?

thedesigntribe

Hello,

I'm currently renovating a house & building a extension. We are putting in three new toliets and are trying to decide on the best position for toilet vents, hoping the one vent will do all new toilets. Two of these toilets are internal - they are not near an external wall so venting is troublesome.

Hopefully someone can answer these

1. What is the purpose of toilet vents? I know they vent bad odours/gases but were do they vent them from. Do the vents, vent odours coming in from the mains sewer or do the vent individual toilets?
2. How close do the vents have to be to the toilets? Is there a rule of thumb?
3. How do large buildings (Hotels etc.) vent a large amount of internal toilets - surely not every toilet has a vent and many would be quite a distance from vents.
4. Any one got an idea where I can read about building guidelines regarding this

I hope this all makes sense :eek:

rooferPete

Hi,

One purpose of the vent is to ventilate the main sewer a bit like a chimney draws the smoke from a fire.

It also provides even pressure by the air being able to escape when the WC is flushed, without the vent any waste would have difficulty passing around the "U" bend without drawing the water from the other sanitary ware on the line.

The larger hotels, offices, etc use air admittance valves (AKA anti Syphon valves) on the run of pipes, usually behind the nice panels we see are service ducts that are ventilated so when the air admittance valve opens it has air to draw in to the system without allowing the odours into service area and escaping into the bathroom areas.

When pressure comes on the system as the air is drawn the valve lifts up and allows air to enter the system and prevents the other WC's from syphoning and blocking the soil stack.

You can dowload the full range of Wavin waste products on www.wavin.ie where there may be better or easier to understand explanations.

Many foul sewers are vented using fresh air inlets on the manholes, it should be fairly easy for a good plumber to advise on the best place to fit a valve if it's needed.

I would expect if a vent is needed it will be sited at the furthest point from the actual soil stack, each system is different I have seen three valves used on 6 WC's while two were enough on the next floor.

The vents are not supposed to actually release foul air into the area where they are sited, the purpose is to prevent syphoning by drawing air pressure into the system so it should be possible to have one end of the run drawing air from the attic, all vents don't have to be 100 mm there are reducers available.

I hope that makes some sense, it's been a while since I had to deal with such systems.

.

flocker

Just a little more info on air admittance valves, to add to Pete comprehensive post .hunterplastics

Another option is to look at the saniflo range of pumped wastes, for toilets showers and sinks that can be put in virtually any location. saniflo

CJhaughey

You could use a rooftile vent, if you didn't have access to an external wall, just run the vent pipe straight up and connect it to the vent tile.

thedesigntribe

rooferPete

Thanks for that detailed knowledgeable post. The explanation of one way air admittance valves is interesting.

When you say:

would expect if a vent is needed it will be sited at the furthest point from the actual soil stack

What is the 'soil stack'? is it the on-street manhole?

CJhaughey
Good suggestion but one of the issues we face is: two of the toilets are located under a 10degree tin roof which receives a LOT of weather from the west. I'm slow to create any more possible leak points that are necessary. So I'm trying to locate the toilet vent elsewhere. I'm fuortunate that the last toilet on the line is under a traditional roof with a steeper slope.

rooferPete

Hi,

Sorry I appear to be making some posts harder to read, I was calling the line of pipe from the first wc to the last as the soil stack, as you referred to it in your reply to CJ.

There are some very easy to use flashings for metal / tin roofs called Deck tite if you think you have to vent through it.

What may work for you is to fit a reducer passed the last wc and use a 2" pipe in the corner and vent it out through the wall just below the ceiling.

You can hire core bits from most good hire shops that will allow you to drill a 60 mm hole in a masonary wall very easy and leave very little finishing work besides making a box for the pipe in the corner.

Make sure it's not coming through the wall near any windows or air vents into other rooms.

.

thedesigntribe

Cheers Pete

We've sourced some flashings to bring the pipe through the tin roof.

Thanks again
Ivan