I'm shopping to replace my waste fittings during a kitchen refit and I've stumbled across traps with an "antisyphon" valve built in, which sounds identical to an Air Admittance Value AAV. If I by this trap then can I cross the AAV off my shopping list? The AAV is more pricey than the trap so this would be a great time AND price saving.
Antisyphon trap. Alternative to air admittance value?
- Thread starter Robin66
- Start date
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Can I just try another quick q since you seem pretty clued up? I've noticed that sink-traps that include an appliance connector (usually washing machine) have the appliance on the clean side of the trap. Is it a big no-no to have the appliance on the foul side? Both washing machines and dishwashers have pumps so I would have thought that there would be no way for foul air to find its way into the room, plus it would reduce the noise coming from the plug hole when the appliance is evacuating
How will you stop foul smell getting back to an appliance otherwise?
I was thinking that the appliance would have a natural trap, being the pump full of water. But thinking about it some more I guess the pump probably operates until all water has been flushed out and so the pump contains air in its rest state, so probably not such a good idea to bypass the trap
Not wishing to discount anyone's opinion but....I believe your thinking isn't far off Robin.
If you've ever emptied a filter in a washing machine you will find that there is a good bit of water left in there. Most appliances have either a built in internal trap or create natural traps either by the drain pipe, being looped over, or by the pump and ancillary pipework at the bottom of the machine having water left in it and it being below the level of the outlet.
In my experience, the pump rarely removes all the water.
If you've ever emptied a filter in a washing machine you will find that there is a good bit of water left in there. Most appliances have either a built in internal trap or create natural traps either by the drain pipe, being looped over, or by the pump and ancillary pipework at the bottom of the machine having water left in it and it being below the level of the outlet.
In my experience, the pump rarely removes all the water.
Personally, i'd be fitting a P-trap / fitting the outlets to a P-trap anyway unless I can see the trap and get at it to maintain.
Not discounting the need for a trapped spigot at all TT.
Was just putting forward a point of view about appliances having internal traps either fitted or induced.
That being said, I've seen machine spigots in-line on waste pipes without traps and without any issues of foul air ingress but I would still agree that a trapped spigot is best.
Was just putting forward a point of view about appliances having internal traps either fitted or induced.
That being said, I've seen machine spigots in-line on waste pipes without traps and without any issues of foul air ingress but I would still agree that a trapped spigot is best.
Not a problem at all, I'm open to other's opinions. How else am I gonna learn. 
Another thing I have seen is where people have created a makeshift trap with a flexi hose from the outlet of the machine strapped to a larger outlet (not sealed). This then led straight to waste and they wonder why they have a foul smell in their utility room.
I think it just saves alot of bother in the long run if you just attach it anyway.
Robin, it's entirely your choice. If you have done your research about your appliances and have the room to attach to the waste pipe after the trap, then have at it my friend.
I hope the installation goes well for you. Just don't bodge it, because the is definitely not OK
Another thing I have seen is where people have created a makeshift trap with a flexi hose from the outlet of the machine strapped to a larger outlet (not sealed). This then led straight to waste and they wonder why they have a foul smell in their utility room.
I think it just saves alot of bother in the long run if you just attach it anyway.
Robin, it's entirely your choice. If you have done your research about your appliances and have the room to attach to the waste pipe after the trap, then have at it my friend.
I hope the installation goes well for you. Just don't bodge it, because the is definitely not OK
Thx for the advice guys. I actually have the waste pipe cut open at the moment without any trap at all, and the room still doesn't smell. I have good access to the area, so I'll probably fit the appliances to the foul side without a trap, relying on the natural trap of the appliance pump/flexible hoses. If someday it starts smelling then I can add a 40mm trap quite easily
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