Syphonage of kitchen sink trap?

[trotter]

Been in my new (well, 1890 ) house 4 months. We have an intermittent problem with smells from the kitchen sink.

The sink waste pipe also houses a connection for the washing machine waste.

I have cleaned out the U-bend etc and it was pretty damn clean on the sink side, bit groggy on the machine side although not enough to block it by any means. The stuff in there had the same scent as the problem, although I guess that might be expected.

Water from the sink clears very rapidly so I don't think it's a blocked drain...

I'm thinking the machine is syphoning water from the trap...the waste pipe for the machine starts low and rises through the side of the cupboard.

Does this sound right and if so...how the hell do I stop it?


ps...it doesn't always seem to occur directly after the machine is used (often wake up to the smell)...maybe it's not the machine after all...would love to solve it !!

 

[Slugbabydotcom]

the waste pipe for the machine starts low and rises through the side of the cupboard.

Make sure the end of the washing mach. waste pipe connects to the sink waste from a higher point.

These probs are best sorted when you can post a picture or two so we can see what you have.

 

[trotter]

the waste pipe for the machine starts low and rises through the side of the cupboard.

Make sure the end of the washing mach. waste pipe connects to the sink waste from a higher point.

These probs are best sorted when you can post a picture or two so we can see what you have.

Aha...I see what you mean

It took me a little time to work it out...but it's actually devilishly simple...doesn't say a lot about my intellect

I will give it a go and will post a pic too

 

[TicklyT]

I had a similar problem a while ago. The kitchen sink and W/M wastes ran into an external back inlet gulley that was backing up, so the ends of the waste pipes were submerged. When the water level in the gulley dropped, it was drawing the traps.
Cleaned out gulley trap (lots of solidified soap scum - almost needed a hammer and chisel!) and everything now behaves itself.

 

[trotter]

On closer inspection, the waste pipe from the WM does actually run slightly downwards into the trap for the last foot or so...

Also, I woke up and the smell was slightly in the air this morning and so I undid the trap straight away - it was full...so I don't think the trap is clearing and allowing smells up...

I suspect that some water isn't clearing the washing machine and is lying dormant and smelling. But I suppose that wouldn't smell stinky.

It could be the pipe out of the house (which doesn't really run downwards until it clears the back wall)...aaarrggghh !!!

 

[Slugbabydotcom]

It could be the pipe out of the house (which doesn't really run downwards until it clears the back wall)...aaarrggghh !!!

Doesnt really run downwards = Running upwards

You know that is where the problem is but you just procrastinated because you didnt want to get up to the eyes in cacky gunge

 

[trotter]

That's the setup under the sink.

The pipes are not blocked (I haven't checked the one heading out though - awkward - but the flow out from the sink etc is good so I don't suspect it's blocked)...and I did look in the trap once when the smell was about...and it wasn't cleared so I don't think it's smells coming up...it's a mystery

 

[bster]

i had a problem with an identical set up like the above, the washing machine kept sucking the water out of the sink trap. Solved it by placing another trap and stanpipe 70cm away and teed into the sink waste pipe below the existing trap (you could try teeing into the length of pipe the goes through the wall).

 

[trotter]

Well, went away for the weekend, the smell kicked in while I was away.

Checked the trap - it was full (I had deliberately run water down it before I left)


What I've done the last 2 nights in drain the washing machine before I go to bed, which tends to drop a pint or two of water...and so far so good...

 

[Slugbabydotcom]

Make sure the end of the washing mach. waste pipe connects to the sink waste from a higher point.

That still stands A good sink full of minging dishwater will run back in to the washing washine the way you have that set up. The pipe runs full bore when you unplug the sink.The water will go anywhere there is enough pressure for it to go rather than running 'river fashion.
Some WM adapters have a non return valve in them to prevent this. 'If' yours does have one it aint working. Its a Big 'If' cos I think it doesnt.

Looking at the pic I can see this might be difficult. I can see why you were putting it off.
Heres a cheat. You dont even have to disconnect a pipe.
Pull the flexible waste pipe through from the WM and make a shepherds crook shape up to a higher point behind the sink.

 

[trotter]

Make sure the end of the washing mach. waste pipe connects to the sink waste from a higher point.

That still stands A good sink full of minging dishwater will run back in to the washing washine the way you have that set up. The pipe runs full bore when you unplug the sink.The water will go anywhere there is enough pressure for it to go rather than running 'river fashion.
Some WM adapters have a non return valve in them to prevent this. 'If' yours does have one it aint working. Its a Big 'If' cos I think it doesnt.

Looking at the pic I can see this might be difficult. I can see why you were putting it off.
Heres a cheat. You dont even have to disconnect a pipe.
Pull the flexible waste pipe through from the WM and make a shepherds crook shape up to a higher point behind the sink.

Yep, I got you, and I was thinking the same myself - it's likely when the sink drains that the machine is filling up.

It's kinda difficult to change that setup, if I teed the machine into the final stretch of pipe I am guessing smells could come from the drain through the machine.

I will do as you suggested or - what about this:

Cut an entire new hole in the cupboard about 4 inches higher and feed the machine pipe through that?

 

[Slugbabydotcom]

Cut an entire new hole in the cupboard about 4 inches higher and feed the machine pipe through that?

4 inches should do it but the higher the better.
Problem is with the backboard in the unit. Sometimes you can drill high up from the left hand side and pass the pipe over the backboard . That way you can get your WM back to the wall

 

[trotter]

Well, this problem is still annyoing us, but my father in law had a look at the drains and he said the kitchen waste joins the soil stack and there is no trap in the drain, it needs digging out and doing properly.

In the meantime I'm thinking of sticking a hepvo trap under there.

I know the hepvo can go straight on the kitchen sink waste but I'm worried the smells will still come up through the washing machine pipe.

Would the hepvo be just as effective outside the house on the external pipe?

Alternatively I'm thinking of putting it on the last run of the internal plumbing under the sink...

Any ideas?

 

[Slugbabydotcom]

Well, this problem is still annyoing us,

So what have you done since your last post?

Did you increase the height of the WM waste?

 

[trotter]

Yes I adjusted height of WM waste significantly, made no difference.

Like I say, my father in law said there is no trap in the drain outside, he will dig it out and fix it eventually... I'm assuming that is the root of the problem.


I'm now trying to figure where to put the hepvo in as a short term fix...