John P
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| posted on 3/6/14 at 07:53 AM |
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Advice on sink drainage needed please.
We recently moved into a bungalow where the kitchen is at the front but the open gully into which the sink discharges is at the back, probably some 8
metres away.
The kitchen has a 1½ bowl sink and also has the washing machine and dishwasher discharging into the waste but there is no trap fitted.
The waste pipe seems to run down into the void space under the suspended floor and then “horizontally” across the full depth of the bungalow before
finally going down at an angle of around 45º then passing through the wall and discharging into an open gulley.
The pipe appears to be 40mm diameter and although there is a fall it’s only quite small.
The problem we have is that although water runs away fine, after the sink is empty there are a series of “bubbling” sounds which can be heard both in
the kitchen and the adjoining lounge which is where the pipe runs beneath the floor. In the sink there appears to be air coming up from the drain
and this can smell quite bad.
I guess it’s something to do with the length of pipe run or the need for venting at the sink end but does anyone have any suggestions. Fitting a
trap below the sink would be quite difficult without wrecking the unit but I could fit a running trap in the under floor space which is reasonably
accessible.
John.
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adam1985
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| posted on 3/6/14 at 08:15 AM |
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You want a anti syphon trap on instead of the standard trap thats proberbly on at the moment. Or tee into the pipework and fit a air admitance valve.
I think screwfix sell 40mm valves
[Edited on 3/6/14 by adam1985]
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cliftyhanger
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| posted on 3/6/14 at 08:25 AM |
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8m is a heck of a run, especially for a kitchen sink. But hopefully the washing machine and dishwasher will keep it clean.
However, are you really saying there is no trap at all on the sink? that is shocking, you really want one and I would definitely fit it in the
cupboard. There are some clever shaped traps around, but do buy quality not unbranded stuff. Well worth the few bob extra. And yes, an air admittance
valve is a good idea, I tend to use them a lot these days.
As to the fall, is there any way of lowering the pipe to increase it? you mention the 45degree bit at the end. I would want as much fall as possible.
And an access eye on the outside so the pipe can be easily poked out with one of those wire thingys when it does get blocked......
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JoelP
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| posted on 3/6/14 at 02:05 PM |
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Minimum fall should be 1 in 40, ie an inch per metre of you don't mind mixing units.
You need some sort of trap to eliminate smells. The gurgle you hear is the water sucking air through the trap like a syphon. You either need a deeper
trap (4 inches) or an anti syphon fitting.
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