Smells

[allanb]

We have a fairly serious toilet smell problem.  I know it's not a new topic, and there's some really useful information in previous threads, but I haven't found the solution yet.

It's an old house, renovated and extended about 25 years ago.  We have no proper plans of the drainage system.  The septic tank is inside the house (which seems odd but I gather is not all that unusual).  It causes a complication, though, because some of the pipes that I'd like to check are hidden inside walls. 

There are two loos, one on the ground floor and one upstairs.  We are fairly sure that the problem occurs only when the upstairs loo is in regular use - which unfortunately means that we have a hard time with visitors, although the smell is not noticeable in the bathroom itself. 

I think I understand (from other people's posts) that I should normally have two pipes from the system to the outside air: one to let bad air out of the tank itself, and one to let air in to the toilet drain so that flushing does not suck water out of the traps.

If this is essentially correct, then I'm concerned that I can only see one: it sticks up through the roof, not quite as high as the ridge, but about a metre above the tiles.  Presumably this is the one from the tank.

This makes me wonder whether the other one (if it exists) terminates inside the roof space.  If it does, and if it's not fitted with some kind of one-way valve, then I could have air from the toilet downpipe escaping into the roof space - which could be the source of the smell.

Assuming this is possible, does it suggest that there is a partial blockage in the downpipe,or cold it happen even without a blockage?  The loo seems to work properly. 

There is a very bad smell in the roof space, close to where the visible pipe goes up, but on a quick search I haven't found a second pipe.  Before I do a thorough search - which will involve moving a lot of insulation etc, so it won't be completely easy - I'd like to ask whether my theory is reasonable: in other words, will I be wasting my time? 

Or does anyone have a better theory?

[Théière]

Sounds right, you can and usually will have a smell without an air admitance device mounted somewhere as flushing can cause a partial vacuum and empty the traps on sinks etc. There should be an air admitance device on the 100mm pipe from the upstairs toilet, called a stub stack in the UK. usually a metre high and tee'd into the 100mm waste pipe.

[pachapapa]

Not usual in france to tee in to fosse vent pipe.

As air admittance requirements are minimal in private residence the function is often achieved by a stub pipe of 40 mm or so connected into the downfall pipe from the loo.

This is often not taken through the roof but is closed with a "reniflard", basically a one way valve containing a rubber disc, opens allowing air admittance during flushing

and closes after to stop odeurs.

Check the following site to see what I am on about:

http://www.nicoll.fr/pub/catalogue/framer_cat.php?niv=3&fampr1=1004&fampr2=2029

I see they are called "clapets aérateurs de chute"; locals here call them renlflards.

Slightly better diagram here;

http://www.nicoll.fr/pub/catalogue/media/photo_cat/CLAPET%20AERATEUR%20DE%20CHUTE.pdf

The termination is left in the roof space see shematic in PDF above; they are very expensive and are traditionally removed when selling a house.[:)]

[just john]

You might only need one pipe as long as there is an air admittance valve correctly fitted which could be the one above the roof; however if this one is only direct to the tank then an air admittance valve needs to be fitted to the soil pipe above the highest appliance point (ie shower, sink, shower, bath etc.) Are internal fosse legal under the new regulations? Our builder insisted on removing our to a new external location[+o(]

 

[allanb]

I assume then that the fact that the system has only one external pipe isn't necessarily a fault, and that the downpipe from the loo could be vented inside the house (e.g. in the roof space) as long as it has the correct one-way valve on the end of the pipe.

I'm beginning to hope that there is such a valve and that it isn't working properly.  Repairing or replacing the valve seems to me to be probably cheaper than anything else I've imagined.

Is a reniflard the same thing as the Dergo or Durgo valve that has been mentioned in other threads?

In answer to just john's question : I wouldn't be surprised if an internal septic tank is illegal in a new building.  The story told by the previous owner was that it wasn't originally an inhabited part of the house.  Whether that's relevant or not, I don't know, but I'm reassured by the fact that when we had the compulsory inspection by SAUR the inspector said it wasn't uncommon, and he didn't mention it in his report.

[pachapapa]

Yes in principle, correct spelling DURGO.

Durgo has a spring, french clapets do not.

Spring is a potential source of problems.

Look at diagrams to see how clapet works!

[mayennesat]

Please see my reply to Finding a fosse in your drive!!!  jyust in case in the future it will be of help.

 

regards

 

keith

[Théière]

[quote user="pachapapa"]

Not usual in france to tee in to fosse vent pipe.

[/quote]

Presumably because it would be pointless [:)]

I did not mean Tee into the fosse vent pipe, I meant the toilet pan down pipe.

In the UK it is a legal requirement for soil pipes that are not external to have an air admittance device, is that not the same in France?

[pachapapa]

[quote user="Théière"][quote user="pachapapa"]

Not usual in france to tee in to fosse vent pipe.

[/quote]

Presumably because it would be pointless [:)]

I did not mean Tee into the fosse vent pipe, I meant the toilet pan down pipe.

In the UK it is a legal requirement for soil pipes that are not external to have an air admittance device, is that not the same in France?

[/quote]

Mille fois oui![:D]

Sorry, mind clicked on 100 mill; down pipes are often 80 mill with 100 mill connection to sewer or fosse toutes eaux.

[allanb]

Thanks for all the information.  I'm about to go up in the roof and do some serious searching. 

I gather that Durgo is a brand name, so what I have may not be identical.  Assuming that the valve is the problem, is there a way of testing them in place?  Are they generally easy to remove and re-install?

Also: there's four or five metres of horizontal distance between the two loos (one downstairs, one upstairs).  It seems highly likely that each would have its own Durgo or equivalent, so I'm looking for two.  Does this make sense?  

[pachapapa]

[quote user="allanb"]Thanks for all the information.  I'm about to go up in the roof and do some serious searching. 

I gather that Durgo is a brand name, so what I have may not be identical.  Assuming that the valve is the problem, is there a way of testing them in place?  Are they generally easy to remove and re-install?

Also: there's four or five metres of horizontal distance between the two loos (one downstairs, one upstairs).  It seems highly likely that each would have its own Durgo or equivalent, so I'm looking for two.  Does this make sense?  
[/quote]

You are more likely to find one made by DURGO in Idaho,Georgia or Mississippi. than rural france.

The french clapet valve has a cover which can be unscrewed for inspection of the elastomer membrane.

Only ONE clapet valve is necessary for each down pipe regardless of horizontal displacement.

The functioning of the valve is clearly shown in the PDF file I have posted above.

But I paste the relevant text as you appear not to have Adobe Reader installed on your computer.

Le dessus de la membrane en élastomère est en contact avec l'air de la chute alors que le

dessous l'est avec l'air ambiant. La chute est donc obturée et empêche la sortie des odeurs

, l'étanchéité est accrue en cas de surpression interne, par contre lors d'une vidange , la

dépression qui s'exerce en amont soulève la membrane et apporte l'air nécessaire pour éviter

tout désamorçage des siphons.

In a nut shell the TOP of the membrane is connected to the down pipe.

The BOTTOM of the membrane is connected to the ambient air outside the down pipe.

SO if the pressure in the down pipe increases the membrane is better sealed and no escape of nasty smells.

ON the contrary when the chain is pulled the water falling down the down pipe will reduce the pressure ON THE TOP of the elastomer

and hey ho the elastomer will lift allowing air to enter the down pipe ABOVE the U bend on the loo and prevent the water being sucked into the down pipe

causing really serious smells.

[allanb]

[quote user="pachapapa"]You are more likely to find one made by DURGO in Idaho,Georgia or Mississippi. than rural france.

The french clapet valve has a cover which can be unscrewed for inspection of the elastomer membrane.

Only ONE clapet valve is necessary for each down pipe regardless of horizontal displacement.

The functioning of the valve is clearly shown in the PDF file I have posted above.

But I paste the relevant text as you appear not to have Adobe Reader installed on your computer.[/quote]Thanks, but I have Adobe and read the file you posted.  I was just asking whether the valve can be removed if it needs attention.  The illustration suggests that it may be glued to the pipe.

Anyway, the first thing to do is to find it!

[Théière]

You can attach them with drain grease, sticky gue that is also used on denso tape so they can be removed if required. I was very grateful to whom ever originally fitted ours as I was able to remove it to modify the pipe work.

[allanb]

Sorry to bring this up again, but - having searched - I've come to the conclusion that there are no Durgo or similar valves in the system.   Logically this means that a single vent pipe, the one that goes up through the roof, is supposed to provide all the ventilation that's required: (1) allowing gases to escape from the tank, and (2) preventing the water from being sucked out of the traps when a WC is flushed. 

So far as (1) is concerned, the pipe has been rodded by a professional roofer, who said that it's "as clean as a whistle".  As for (2), I presume it's working because the problem has never been apparent in either of the bathrooms.  (This also suggests that there's no point in fitting air admittance valves directly on the toilet downpipes, although there would be enough space.  Does this make sense?)

So I am beginning to think about the possibility of something like a cracked pipe or a leaking joint, which could be a disaster because if there is such a thing it's probably somewhere underneath a concrete-and-tile floor.

Can anyone think of anything else I could usefully try, before I start tearing out the floors?

[Chancer]

I too have been suffering a smell in my bathroom and was concerned that it might be the badly positioned aerateur à membrane, I have no-one else to blame as it was I that did the plumbing in my ignorance.

I think that I have now found the cause or at least removed the major part as perhaps there is a secondary niff present.

I have a cabin shower with one of those inverted cup type traps that used to drain down so slowly that you were ankle deep by the end of showering, I had removed the lower sleeve from the trap which allowed it to drain much faster and I thought this would be OK as I (thought that) had  managed to form a U bend in the flexible outlet pipe during the original installation.

I think that the U bend was either my imagination or is not working and its a real work up to remove the cabin so I replaced the lower sleeve/cup of the trap, result barely any smells other than the usual "I wouldnt go in there if I were you mate" type temporary ones, so I am sure that each time I flushed the toilet which is just upstream from the shower the smells were wafting up through the shower, I dont really have enough fall either which must have exacerbated things.

Do you by any chance have one of these showers?

One thing that always confused me was that the VMC didnt seem to remove the smells but perhaps it was sucking air into the room from the shower trap, that and the fact that methane is heavier than air [:P]

[allanb]

Chancer: I don't think that's my problem, since I don't have any "non-temporary" smell in the bathroom.  Nevertheless, I'll add it to my lengthening file on this topic.  You never know.

Thanks.

[Chancer]

Twas pretty permanent in my case as the bathroom discharges straight into a regard leading to the sewer and there is no stack pipe to take the stink away,basically the VMC was taking air out of the room which was being replaced either by air coming in around the volet roulant or up through the sewer via the shower.

It has taken me a couple of years to carck this smell, what worries me is that I remember someone complaining about their slow draining shower and I advised them to take the sleeve out of the trap, ooopps!!! [:D]

[Théière]

[quote user="allanb"]Sorry to bring this up again, but - having searched - I've come to the conclusion that there are no Durgo or similar valves in the system.   Logically this means that a single vent pipe, the one that goes up through the roof, is supposed to provide all the ventilation that's required: (1) allowing gases to escape from the tank, and (2) preventing the water from being sucked out of the traps when a WC is flushed. 

So far as (1) is concerned, the pipe has been rodded by a professional roofer, who said that it's "as clean as a whistle".  As for (2), I presume it's working because the problem has never been apparent in either of the bathrooms.  (This also suggests that there's no point in fitting air admittance valves directly on the toilet downpipes, although there would be enough space.  Does this make sense?)

So I am beginning to think about the possibility of something like a cracked pipe or a leaking joint, which could be a disaster because if there is such a thing it's probably somewhere underneath a concrete-and-tile floor.

Can anyone think of anything else I could usefully try, before I start tearing out the floors?[/quote]

A plumber will be able to carry out a drain pressure test for leaks, it may cost a few euros but better than ripping up the floors.

[partout]

Having had some really horrid smells lingering around the top floor of our house, we had contacted a plumber (for another job) and he came to have a look, and it was put down to having no stink pipe from the loo. The loo was in the loft, and the sewerage pipe was installled by the previous owners with no stink pipe. A stink pipe was fitted out through the roof and above the velux, and now pleased to say no more horrid smells, and the flies have disappeared to boot!

[Chancer]

I am currently fiting out two studios in the loft, a similar situation to yours I think.

I would not dream of using an external stack to vent the soil pipe in these circumstances as ordinarily you would not be able to get the top of the stack high enough to conform with the normes and avoid smells entering through the veluxes, I have a kitchen beside where the stack would be. In my mind this is exactly the circumstance where an aerateur à membrane should be used.

I assume that your installation did not have one before.