Plumbing problem, kitchen DW & Sink

[dedee]

Can anyone help with a kitchen plumbing problem?

I've just discovered that when I empty the kitchen sink at the same time as the DW is being emptied that water comes up the vertical pipe thet it (DW) drains into

The DW is to the left, sink in the middle and WM on the right. The waste flows away to the left.
I've checked all the traps and they are very clean. I've run a flexi-shaft cleaning device through all the pipes both in the kitchen and in the garage underneath and all appears to be OK.

I suspect that DW waste cannot break into the faster flowing rush of water from the sink.

Is there anything I can do to prevent this happening again?
Would having the sink waste on the left (down stream of the DW) and moving the DW to the middle have any effect solve the problem?

cheers

Andy

 

[Digit]

It's a common problem Andy when the length of the waste pie is lengthy or when the incorrect diameter pipe is used. The waste should be inch and a half, not inch and a quarter.
The only effective solutions, if the waste is inch and a half, and not restricted, is to shorten the pipe, increase to two inch diameter, move the DW waste connection further from the sink or instal a separate DW out flow.

Roy.

 

[dedee]

Roy, thanks for the reply.

All the pipes are indeed 40mm or 1.5".

The only effective solutions is to shorten the pipe, increase to two inch diameter, move the DW waste connection further from the sink or instal a separate DW out flow. Roy.

Which pipe would need to be shortened?

Increasing the pipe to 2" is a non starter as the 40mm pipe goes through a 45mm hole through a concrete floor.

How far away would you think the DW connection should be form the sink? I could only move it , at most, 50cm to the lefts before the pipe goes down through the floor.

Cheers

Andy

 

[wobblycogs]

Sounds to me like Roy has hit the nail on the head and that you are a bit stuck regarding a fix. Personally, I'd try replacing the sink trap with something like this http://www.screwfix.com/prods/12794/Plumbing/Wastes-and-Traps/Sink-Washing-Machine-Trap-40mm and then jubilee clipping the DW on. The DW waste is pumped and I'd imagine it would provide enough force to get the water into the sink outflow. Worst case the water will back up into the sink rather than into the cupboard which is what I imagine is happening now.

 

[Racers]

Hi, Andy

Are your T peices the right way round?

Pete

 

[dedee]

Pete,
Yes, checked all the T pieces all flowing the right way.

Wobbly cogs, I'd always though that the vertical pipe waste was the better method but as you say backing up into the sink is preferable that waht is happening now.

Cheers

Andy

 

[Digit]

I gather from your post Andy that in the garage below the pipes are commoned, if this is so it means that the pipe diameter is too small/the length too long for the combined flow, therefore moving the dishwasher connection nearer to the drain, or plumbing separately, will solve it.
Alternatively wobblecogs suggestion is possible the easiest route.

Roy.

 

[Racers]

Hi, Andy

Can you extend the DW waste pipe higher? so its above the water level of the sink. Its the only thing I can think of apart from running bigger/more waste lines.

Pete

 

[dedee]

Pete, the vertical pipe is about as close to the underside of the worktop as possible.


Would one of these also be suitable?

http://www.screwfix.com/prods/91793/Plu ... -Trap-40mm

Cheers
Andy

 

[wobblycogs]

Pete, I don't think making the DW waste pipe higher (within reason) would solve this problem even if it was possible. The additional pressure gained from a few more cm of water probably still wouldn't be enough for the DW waste to force it's way into the flow coming from the sink and possibly washing machine.

Andy, yes that trap should work fine. All you need is a trap with an integral hose connection. The end of your DW hose will be rubbery and should push onto the hose connector, I always clip it as well to be sure I would imagine zip ties be enough if you don't have a jubilee clip available.

 

[dedee]

WC,
I'm off down the plumbing shop right now.

I'll jubilee it just to be sure.

Thanks all

Andy

 

[Digit]

One rider there Andy, when you connect the DW hose to the new trap create an upside down 'U' in it, I normally screw a hook into the underside of the worktop then tie the hose to it. Failure to do this can result in the water from the sink ending up in the DW.

Roy.

 

[dedee]

Thanks Roy, there is plenty of hose so that should not be a problem, other than the worktop is silestone and might not be too easy to screw into - I'll stick it up with duct tape.

I've got the parts now so will fit in the morning.

Cheers

Andy

 

[Alex]

In tricky situations like this I usually fit an air admittance valve.
http://www.screwfix.com/prods/42968/Plu ... -40-x-50mm
It will increase flow on existing waste pipes by letting air in and breaking the vacuum that will suck water out the other traps. Just remove elbow after sink trap and fit a tee with a riser so air valve is 2" above all other inlets. It works fantastic on slow bath drainers as well. 8)

edit-looks like you might have it sorted but beware as Roy says slow drain might put water in DW. I tend to use these http://www.screwfix.com/prods/42868/Plu ... in-Out-Kit
because they have a sprung one way valve.

 

[Digit]

I used to use those one way valves Alex but gave up on them as I found they clogged eventually and the customer always seemed to think it was my fault! :lol:

Roy.

 

[dedee]

I've fitted the appliance trap and the DW hose is tucked up the side of the sink about 8" above the trap inlet

Is there anything I can use to improve the seal between hose and inlet spigot? I can't seem to get a good seal. The DW hose is a very loose fit on the spigot, I've tightened the jubilee clip as much as possible but I still get a drip from the end of the hose. The drip is definitely coming from the end of the hose and not from any hole that I might have made with the jubilee clip cutting through the hose. I've had this off and checked a number of times.

Alex/Roy, the inlet does in fact have a kind of one way valve in as much as the centre of the washer is not entirely cut out.

BTW when DW and sink are emptied at the same time all that happens is the sink empties a lot more slowly than before which I am quite happy about as this is in fact quite a rare occurrence.

Cheers


Andy

 

[hanser]

Andy

Re the drip from the hose to spigot connection......

Funny how the simplest of jobs turns into hard work/headscratching. We've all been there at some time!

There are a few options that I'd try .....beef up the spigot with a wide tape or use plumbers mate or the dreaded silcone to wipe round the spigot/the inside of the tube. Another possibility would be using something like "hylomar blue" -available from car accessory shops. http://www.paddockspares.com/scp/SHOP_B ... lomar.html

If you are 'gunkink' the spigot, clean up the inside once you've tightened up otherwise you may find a ridge of material that eventually will catch grease etc and partially block up

Personally I'd probably use that - but only because I've got some in my toolbox!

 

[bugbear]

Can I just say "yikes" at the location of those power sockets under the sink?

BugBear

 

[dedee]

HAven't got plumber's mait only boss white which I dod not think is the same. I could try with silicon I suppose

Funny how the simplest of jobs turns into hard work/headscratching. We've all been there at some time!

Oh how true, I now have a leak in the pipes in the garage. I cleaned all these out yesterday and now one of the welded plastic joints is leaking.... How on earth can I fix or do I have to cut the piece out and start again?

BB, this is in France, normal safe practices, part P H&S etc don't apply. I even have a socket 6" away from a sink in the bathroom.


Andy

 

[Digit]

Take the hose off, dip it in boiling water then tighten it again, alternatively leave it till the DW dumps hot water and try tightening again.
One or the other usually works.

Roy.