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1. strike - Member

   We've got an on-going issue in our bathroom, with the smell of drains/sewage.

   It seems to be worse when you're out for the day and you come home - like last night!

   We've got the sink/bath/toilet all in one bathroom - these connect to the waste pipe which goes along underneath the bathroom floorboards, then under the main bedroom floorboards, and exits on the back wall. The waste pipe then runs vertically down from here.

   When I walked in the conservatory last night (the lower section of the waste pipe runs down the conservatory wall) I could smell the bad smell, and it just got worse the close I got to the bathroom (upstairs).

   I'm reading about causes such as failing/dry traps.

   Anyone know a bit more/can explain where to start, please?

   Posted 3 months ago #
2. Stoner - Member

   as far as my understanding goes, when you flush the bog (or in some circs, empty the bath/basin) the waste creates a partial vacuum in the waste pipe upstream. If you have shallow shower traps with very little water in, the partial vacuum can be sufficient to syphon the trap water into the waste pipe so that the trap is no longer functioning as a smell barrier.

   To overcome this one usually has either an external stack vent (which usually goes up the outside of the house or through the roof, or a 110mm Air Admittance Valve in some vented box work near the bog in the bathroom. However, some of these large AAVs I think dont let air in at a low enough negative pressure and if the emptying trap is upstream of another appliance outlet (such as the bath) then the main soil AAV isnt going to do anything to prevent syphoning of the shower trap water)

   I had a similar problem (not the smell, but an annoying gurgling noise) and solved it by fitting a small Air Admittance Valve in the 40mm waste run under the sink. Its worked a treat and lets air in when the bath or basins drain without drawing the water from the shower trap that is at the other end of the pipe run.

   
   http://www.drainageonline.co.uk/40mm-Solvent-weld-Waste/Air-Admittance-Valve---Ventapipe-25.htm%3Futm_source%3DDrainageOnline%26utm_medium%3DFroogle%26utm_campaign%3DShopping

   Posted 3 months ago #
3. wwaswas - Member

   you can get anti vacuum wastes for the sink and bath that do the same as that valve thing, too. Screwfix sell them.

   Do you ever get any odd noises out the sink etc when you flush the loo? If you do that's the water in the trap being sucked down the pipe.

   Posted 3 months ago #
4. strike - Member

   Nope, never any odd noises at all!

   To overcome this one usually has either an external stack vent (which usually goes up the outside of the house >> we do have this

   However, some of these large AAVs I think dont let air in at a low enough negative pressure and if the emptying trap is upstream of another appliance outlet (such as the bath) then the main soil AAV isnt going to do anything to prevent syphoning of the shower trap water)>> we do have an external drain pipe (from part of the roof gutter) that has been tapped in to the waste pipe, where it runs vertically down the side of the house. So I'm now thinking is this the root cause of the problems?

   Thanks for the replies.

   Posted 3 months ago #

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