Wind causing seal in shower trap to break causing odours

s00bf06e

Hi all, I have a problem with the water trap in our showers breaking when there are high winds. It was happening yesterday evening with the north easterly winds, causing a bad smell on the downstairs bathroom, I could even see the water level in the toilet moving up/down with gusts of wind. We are a two story house, the first thing I tried was to reduce the vent stack height from above the slate height to below the eve., but it hasn't helped much. We are quite exposed to the wind and it is obviously causing suction/vacuum that is causing the seal to break. I was thinking of drilling holes in the top 2 foot of the vent stack on all sides to try prevent the vacuum effect and then I came across 'air admittance valves' on screwfix and thought they might be a solution. Would any of these help or what is the best solution. The showers are walk-in and tiled so I don't think I can do much with the traps that are already installed. Any help/ideas appreciated.

Can you see the wastes from the showers outside ?
maybe you could fit another trap outside.

s00bf06e

No, none of the pipework for this shower is above ground. I think doing something with the vent to reduce the pressure/vacuum is my only real option, but im not sure what is the best thing to do. I dont want to spend €20 on the admittance valve if drilling a few holes will solve the issue

dbas

s00bf06e wrote: »

No, none of the pipework for this shower is above ground. I think doing something with the vent to reduce the pressure/vacuum is my only real option, but im not sure what is the best thing to do. I dont want to spend €20 on the admittance valve if drilling a few holes will solve the issue

How is the vent pipe connected to the shower if the shower trap and pipework is below ground?

Do you know the layout/connections of the hidden toilet and shower waste?

policarp

I presume you have a septic tank, otherwise all your neighbours would have the same problem.
If so the syphonic effect could be coming from there.
Try a wind cowl on your vents. (House and septic tank.)
I wouldn't be inclined to fit any sort of restrictor to the vent pipe.
That could be dangerous.

s00bf06e

The shower layout is: trap into about one foot of 40mm pipe which is T'd into 110mm waste pipe , the toilet is T'd into the into the same 110mm waste pipe about 1.5 meter upstream of the shower. The waste pipe goes out through the wall under the floor and is then vented up to the eve. the upstairs bathroom connections T in at the first floor

s00bf06e

policarp wrote: »

I presume you have a septic tank, otherwise all your neighbours would have the same problem.
If so the syphonic effect could be coming from there.
Try a wind cowl on your vents. (House and septic tank.)
I wouldn't be inclined to fit any sort of restrictor to the vent pipe.
That could be dangerous.

We have a septic tank which has a vent but I though there would be a water seal there as I think the input into the septic should be below the static level within the septic tank.

Maybe I will try the 'air admittance valve', the wind was howling through the pipes last nite, I ran the shower a few times but within 5 min the seal was gone.

dbas

s00bf06e wrote: »

The shower layout is: trap into about one foot of 40mm pipe which is T'd into 110mm waste pipe , the toilet is T'd into the into the same 110mm waste pipe about 1.5 meter upstream of the shower. The waste pipe goes out through the wall under the floor and is then vented up to the eve. the upstairs bathroom connections T in at the first floor

Is there a roof overhang covering the top of the vent?
If so, 2 no. 110mm 90 bends to loop around overhang to clear the roof.

Have you any way of checking the depth of the current shower trap? It may be a bit shallow

s00bf06e

dbas wrote: »

Is there a roof overhang covering the top of the vent?
If so, 2 no. 110mm 90 bends to loop around overhang to clear the roof.

Have you any way of checking the depth of the current shower trap? It may be a bit shallow

The vent did originally have 2 x 90 bends to bring it out over the eve, but the problem was still there. We are very exposed to winds.

Yes the traps are a bit shallow, they are a low profile enough and tiled into the floor in the we room. I was thinking of taking a hack saw/dremel tool to the underside of the cap in the trap to try make the trap a little deeper but I would only get a few milimeters extra, thats why I though I would try something at the vent.

dbas

s00bf06e wrote: »

The vent did originally have 2 x 90 bends to bring it out over the eve, but the problem was still there. We are very exposed to winds.

Yes the traps are a bit shallow, they are a low profile enough and tiled into the floor in the we room. I was thinking of taking a hack saw/dremel tool to the underside of the cap in the trap to try make the trap a little deeper but I would only get a few milimeters extra, thats why I though I would try something at the vent.

I'd try the wind cowl idea on the vent stack first.
Sounds like the wind is blowing down the stack and bursting the smallest trap.

Is there any way for the system to vent between the tank and stack.

s00bf06e

dbas wrote: »

I'd try the wind cowl idea on the vent stack first.
Sounds like the wind is blowing down the stack and bursting the smallest trap.

Is there any way for the system to vent between the tank and stack.

Maybe I will try a cowl or the admittance valve, the only way it could vent between the vent and the septic tank would be through one of 2 access manholes but then I would worry about smells near the back of the house or in the garden.

Thanks