Smells from sink when appliances drain - need anti vac trap?

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Hopefully this is just a quickie for those in the know :)

We're getting some pretty minging smells from our utility room sink whenever the dishwasher or washing machine drains out. Both appliances have their wastes connected into the sink trap, via this kind of arrangement:

ae235


Am I right in thinking that I need to add some sort of anti syphon protection to stop the smells? If so, would replacing the U-bend section with an anti-syphon trap work?

12002.jpg
 
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Youre right... Or there is partial blockage that cause to siphon, or just increase the pipe size is better solve the problem
 
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Great. Here's a pic of the trap:


It's a McAlpine trap. The outer diameter of the black waste pipe is 42mm; that makes it 1.5 inch, correct?

Am I right in thinking that if I buy a McAlpine SC10V, it will just replace the lower section without having to alter any of the pipework?

mcalpine-1.5-antivac-kitchen-sink-p-trap-sc10v-40004001-%5B2%5D-1641-p.jpg


mcalpine-1.5-antivac-kitchen-sink-p-trap-sc10v-40004001-1641-p.jpg


Alternatively, I could just buy a WM11V, which is the same trap as I have now but with anti syphon fitted.
 
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You'll need to replace the lot, the new trap in your photo's is to fit straight onto the waste, the trap you currently have on the sink is the telescopic type to allow flexibility with the distance between the waste and the outlet pipework.
 

ree

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The loop-in waste lines from your appliances should leave the appliance connection, and quickly rise to be fixed below the work top, and then be fed through to the sink cabinet, where they will drop and pick up the trap hose connectors.

Your loop-in lines are drooping, and coming up from low to make the trap connection, and will be retaining waste water and food debris. Some waste retention is inevitable but you will also run the risk of other difficulties & blockages.

FWIW: its best practice to use jubilee clips at the hose connectors.

FWIW again, google pics/check out the Air Gap devices esp. double air gaps on US plumbing supplier's sites. Air Gaps are Code(Regs) required in some states.
 
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Alternatively you could cut in a durgo (or air admittance) valve. This will allow the pipe to draw air in, so it doesn't suck the water out of the trap, whilst not letting foul air out.
 
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Excellent info, thanks all!

I'll replace the trap with a wm11v, and see if I can re-route the waste hoses; I'm not too hopeful about that though, options are limited for access.
 

ree

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I dont understand, and i dont mean this unkindly,

typically, if the hoses can snake thro low they can go thro high.
You've entered the building trade, albeit at the DIY level, but the idea is not to give up: "not too hopeful" but to make it work.

Pull your apps, and remove the plinth if necessary, empty and remove shelves.
Think thro what you are about to do.

Maybe its all too much trouble for whatever benefits, which is understandable.
But to pack it in at the first obstacle ...
 
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I won't give up!

Thinking about it, I probably do need to sort out the waste pipes. My dishwasher is to the right of the sink, then the washing machine is to the right of that; so, I had to fit a waste pipe extension to the washing machine... there's a fair bit of that coiled up under the units. That's not likely to be doing me any favours...
 
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Extensions on waste hoses are never a fantastic idea, whilst there is a non return valve on the machine, it can still result in a plug of water stagnating in the hoses. As Ree has said, better if the high point is as close to the appliance as possible to allow the hose to drain under gravity. (Although the US regs are probably somewhat different to the UK!) ;)

Ideally, I would be looking to provide a waste at the appliance to remove the water at source, rather than extending hoses to reach a suitable discharge point.
 
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Unfortunately, I can't really do that as the waste pipe goes underneath the floor. To tie anything else into it, I'd have to rip out the whole utility room, take up the engineered wood floor, then start pulling the floorboards up...


Bit of an oversight really that I didn't plan in the waste pipe allocation when I had the chance. I think the best I can do now is try to elevate the drain hoses as suggested. It will be tricky but I have the feeling if I don't do it I'll be back at some point with a horror story...
 
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