Avoiding noise and smells when making waste for dishwasher?

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Hi all

I’m installing a new kitchen and wondered what the best way is to do the waste outlet for the dishwasher. It’s a fitted kitchen therefore limited space behind appliances/cabinets. As the kitchen/lounge are open plan I’m very keen to avoid smells (drain smell / stagnant water) and sink gurgling noise. Dishwasher is next to sink, so I was planning to bring the d/w waste into the sink cabinet.

The room doesn’t have any existing pipework yet apart from the 50mm in a corner near sink cabinet.

I will be looking to fit an anti-syphon bottle trap on the sink, and also an AAV between sink and dishwasher - overkill??

I don’t know what to do with the type of trap. I’m guessing in the ideal world a spigot sort with a small U bend fitted inline on the branch pipe after the AAV would be best if I could find one. I saw the Hepvo traps, they’re a bit pricey (especially as I probably need one for the washing machine too!), but if that’s what’s recommended and best then I’ll take the hit. I don’t like the sink trap connected spigots as I’m certain that’ll cause gurgling, and with the standpipes I’m bothered about smell - plus I’m not sure if it’s advisable to cut them down in height as they won’t fit inside the sink cupboard anyway without being cut.

Any suggestions or kind advice anyone please?


Cheers,
Dave
 
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Here's mine. The only gurgling comes from the actual dishwasher itself, zero odours.
IMG_20220119_092555593.jpg
 
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Use a standpipe, it can be cut down a bit but dont go mad, or it could overtop if crud buildup reduces flow capacity over time. If you cant get sufficient height, then you will need to look at putting the waste lower to provide the required height.

You need an air break between the outlet hose and the waste, hence why a either a standpipe is used or discharge into a sink trap is made above the water level, otherwise dirty water could re enter the machine.
 
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Thanks everyone for all your replies, looks like standpipe wins 3/3 so that’s what it’ll be. I’d have to chop it down to about 21” above trap water level but assume that’s ok? I’ll obviously ensure the flexi pipe doesn’t jump out or dip into the trap water.

cheers, Dave.
 
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(I couldn’t add the “thanks” to you Hugh, it’s greyed out so no hard feelings but thank you all the same!)
 

MJN

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I might be misunderstanding your setup or concerns, but I fitted a McAlpine space saving trap and connected the adjacent dishwasher to that. No gurgling, no smells, no problems at all?

20210117_123928.jpg
 
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Use the plastic 'U' shaped former that should be supplied with the machine, hook the hose into the standpipe and it should remain firmly in position.
 
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Lovely looking job there MJN - I’ll aim to be as neat as that! I see the venting is done through the sinks too, so gets rid of need of AAV I reckon, and probably a good distance from the dishwasher spigot to the trap to avoid it blasting out the trap water or making too much noise me thinks too.
 

MJN

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It doesn't really make any noise at all, and that would be an issue as like you this is in an open plan family room.

In all honesty I don't have any personal experience of standpipes, but to those that are recommending one don't they make a lot of noise by virtue of the distance the water has to fall into that sitting in the trap?
 
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I might be misunderstanding your setup or concerns, but I fitted a McAlpine space saving trap and connected the adjacent dishwasher to that. No gurgling, no smells, no problems at all?

That looks good, nice and neat. It will be nice and quiet because the appliance is plumbed into the right hand spigot and when the appliance pumps the flow's quite straight so much less turbulence (noise). If the left hand spigot was to be used you may find there would be more turbulence (noise).

That and that install is brand new by the looks of it and if it's cleaned out regularly then it should stay nice and fresh and scent free, but if it isn't ..... :sneaky:
 
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I see the venting is done through the sinks... and probably a good distance from the dishwasher spigot to the trap to avoid it blasting out the trap water or making too much noise....
The usual cause of the gurgling that you're keen to avoid is a poorly designed pipework system downstream of the trap. Use the correct size of drain pipe and the correct downward slope (1 in 40 to 1 in 25). Too shallow and debris will drop out of the water flow (de-watering), plus the risk of airlocks. It is designed to allow air to flow UP the drain pipe as the water flows down, avoiding sucking down at the trap), so too much slope will block that return air and cause glugging.
 
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