Downstairs bathroom sometimes smells after flushing (Durgo Valve?)

[mjgreen81]

Hi all,

We have a downstairs bathroom with toilet, basin and shower. The toilet is fitted with a Durgo valve. The downstairs bathroom is an extension to the house which was fitted probably 15-20 years ago.

We have noticed over the last few months that sometimes a foul smell (its not me, honest!) is emitted after flushing. This happens about 50% of the time I would say. I have not managed to pin down exactly where the smell is coming from, but it definitely only affects the downstairs bathroom. The smell might be emitted for a few flushes and then all of a sudden it goes away. Then a few flushes later, it comes back.

This may or may not be related, but about 18 months ago we had our main upstairs bathroom done which included fitting a shower and replacing the full length soil stack (which went through the roof) with another Durgo valve upstairs.

Since having this work done we have not used the downstairs shower.

Until Googling it this morning, I didn’t have a clue how a Durgo valve worked (I wondered if it might have some kind of filter in it which would need replacing), so now have a little more understanding.

• Is it possible that the Durgo Valve is sticking and needs replacing?

• Could it be to do with the Durgo valve that was fitted upstairs? Several things since have shown us that the installer had some unusual way of doing things and I wonder if it wasn’t fitted correctly (does it have to be fitted above the u-bend level of the toilet/WHB or something?)

• Is it likely to do with the downstairs shower that we now never use?

• Anything simple I can try (I have tried chucking drain cleaner etc down the WHB/shower waste and it has made no difference)?

Thanks all

 

[Jadele]

are you sure the shower drain is not drying up allowing gas to come past the trap and in to the bathroom?

 

[mjgreen81]

I guess its possible as it has not been used for a long while. I am just surprised that the smell seems to come and go if this was the cause

I will certainly try that as my first step...

 

[Jadele]

if its dry it most likely will be when you clean the bathroom perhaps you top it up again so the smell goes then it drys again hence the coming and going. Also windy conditions will make it more noticeable as the wind will push down the soil stack and force are through the dry trap.

 

[mjgreen81]

if its dry it most likely will be when you clean the bathroom perhaps you top it up again so the smell goes then it drys again hence the coming and going. Also windy conditions will make it more noticeable as the wind will push down the soil stack and force are through the dry trap.

Clean the bathroom? huh?

No seriously, over the course of one evening (with no cleaning going on or water going down the shower drain) it can be fine one minute, then following a flush you go back into the bathroom a few minutes later and there is the smell. Then an hour later, its gone again.

I suppose the wind could be a factor though. Although, we don't have a soil stack which vents out to the atmosphere since the upstairs bathroom soil pipe was replaced with a durgo when the upstairs bathroom was done.

 

[Jadele]

Clean the bathroom? huh?

Although, we don't have a soil stack which vents out to the atmosphere since the upstairs bathroom soil pipe was replaced with a durgo when the upstairs bathroom was done.

Thats not the best since all the gas will be built up in your stack. Most likely then just the flushing action pushing air around the stack and through the shower or something.

 

[mjgreen81]

Thats not the best since all the gas will be built up in your stack. Most likely then just the flushing action pushing air around the stack and through the shower or something.

I am just trying to read up on this. I am seeing mixed opinion about whether just having durgo's is OK or whether you still need a soil pipe exiting to the atmosphere.

Feeling a bit confused!

 

[Jadele]

I am no expert and I don't know if its required by regs or not to have it vented but if no one had one there would be a problem with flammable gas buildup I would of thought

 

[bernardgreen]

The Durgo is an Air Admittance Valve. It allows air INTO the stack pipe to prevent low pressure ( caused flushed water falling down the stack pipe ) sucking of water out of U bends.

The sewers serving you house should be ventilated to outside fresh air to prevent high pressure building up in the sewers and forcing sewer gases through U bends and into the house.

 

[Hugh Jaleak]

Building Regulations state the head (highest point) of the drain should always be open to atmosphere. If a vent is there, it is there for a reason, people keep removing vents and fitting AAV's then wonder why they have problems. Drains need to 'breathe', and if they cant, positive pressure that builds up, will find it way out somewhere, in this case it seems to be your downstairs bathroom.

I work for a water company, and part of my job involves cleaning of sewers. This is done using high pressure water jetting, and we are now finding increasing problems with 'blowbacks' whereby the pressure being created by the jetting head, is causing toilets to erupt and redecorate the bathroom, particularly on the ground floor. This happens, simply because the drain cannot breathe, and invariably upon investigation, we find an existing vent has been removed and an AAV fitted in its place.

My initial advice would be to check the drains are running clear, your symptoms can often be a sign of a blockage. When you flush, you are adding to the build up of effluent, the air that is then displaced, (as the waste cannot escape as it should), needs to find a way out, so will bubble back through the point of least resistance, usually an appliance trap, e.g. a shower. If this shower isn't being used then its also possible the trap has dried up, or has less water in than it should. Run the shower once a week to clear the standing water out the supply pipework and make sure trap is replenished.

I would also strongly advise the vent is restored.

 

[Hugh Jaleak]

Please folks, if you don't understand what you are commenting on, don't comment! All you are doing is confusing the issue.

 

[mjgreen81]

Thank you all for your advice, you have really helped me to understand the situation and the cause of the issue.

It sounds like my bathroom installer screwed up by removing my vent out of the roof and replacing with the AAV. Sadly, I am not surprised by this

Will have to have a think what to do now. Thanks again for the advice, this truly is a great forum.

 

[Madrab]

Unfortunately there isn't really much to think about @mjgreen81 . If the original vent has been removed then as @Hugh Jaleak has advised, if you want your system to work correctly, it needs the work described. Get it checked for restrictions (have you noticed any slow draining or the toilet water rising in the bowl when flushed) and then get the external vent re-instated to ensure your soil pipework works as designed, that then gets you back to the right starting point.