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Help to locate source of unpleasant odour!! (Read 10721 times)
Tika
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Help to locate source of unpleasant odour!!
Feb 2nd, 2016, 11:27am
 
Hi, I have recently bought a lower ground floor Victorian converted flat (4 others above) with an internal bathroom. It has a Silavent fan on a chimney breast extracting into the flue. The fan operates okay (sucks in a tissue held nearby) and is wired up to operate whenever light is on. So far, so good..... now the problem -  randomly, but frequently, there is a foul smell only when the fan is in operation (as though someone has been eating cabbages and baked beans!). I can't turn the fan off or the light won't work! I have been told that each flat extracts air into their own flue, so what could this smell be and how can I rectify the problem? Could anyone suggest what sort of tradesman I should call in - is it the job of a builder, a plumber or an electrician? All help gratefully received!
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woodsmith
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Re: Help to locate source of unpleasant odour!!
Reply #1 - Feb 3rd, 2016, 9:11am
 
Hi, sounds to me that when the fan is running it is creating a negative pressure in the room and this is drawing smells out of one of the traps in the sink, bath or shower. Try leaving the door open with the fan running and see if this solves the problem. If it does then check that the traps are ok. However it may be that the bath has a very shallow trap which could be replaced with a Hepworth V2o trap (this is designed to run level with no need to hold water). The other thing to look at is if the door fits too tightly against the floor at the bottom, there needs to be a decent gap so that air can be drawn into the room once the fan starts running.

Hope this helps
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Tika
Re: Help to locate source of unpleasant odour!!
Reply #2 - Feb 3rd, 2016, 7:21pm
 
Hi, thanks for your reply. The bathroom is all brand new - presumably renovated in order to sell the flat, so I assume the traps should all be clear. They don't seem to smell. There is clearance under the door and having the door open has no effect. The smell seems to be drawn in from somewhere by the fan itself even though it has reasonable suction. I wondered whether we could somehow be getting the extracted air from another flat's bathroom? That would explain why the smell is random, but doesn't make sense if the flues are separate.
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woodsmith
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Re: Help to locate source of unpleasant odour!!
Reply #3 - Feb 3rd, 2016, 11:14pm
 
I would imagine that if the ducting was shared you would get the smell when the other party turned on their fan but not when you turn on yours. I would get some steps out and have a sniff at the vent then turn it on to see if it smells worse. Other than that check the joints between the floor and the walls and if possible take the bath panel off and see if there is anything amiss under the bath.
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Re: Help to locate source of unpleasant odour!!
Reply #4 - Feb 3rd, 2016, 11:49pm
 
I would be amazed if they drop a seperate pipe/duct down the flue for each unit.

If it's new/convert I would be getting the builders back in to sort it under warranty.

Saying that check the unit isn't shorting out/getting hot/full of soot.
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Tika
Re: Help to locate source of unpleasant odour!!
Reply #5 - Feb 4th, 2016, 11:26am
 
It's an old convert that had a new bathroom fitted just prior to sale and I can't find out who the builders were. The unit smells fine and doesn't appear to have any problems, although I would guess it was the cheapest they could find so don't know if it's worth just changing it. Under the bath is clean and there are no cracks or gaps anywhere. I have met someone who rented the flat for 5 years prior to its sale and he says he never had this problem, which seems to suggest it is as a result of its refurbishment, but what could it be? Could they have somehow accessed someone else's flue? I am happy to call someone in, but don't know what type of tradesman I should call! Thanks for all your suggestions; it is much appreciated.
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thescruff
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Re: Help to locate source of unpleasant odour!!
Reply #6 - Feb 4th, 2016, 10:34pm
 
Check under the bath etc to check whether there's a waste or soil pipe left open ended.
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« Last Edit: Feb 4th, 2016, 10:35pm by thescruff »  
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Tika
Re: Help to locate source of unpleasant odour!!
Reply #7 - Feb 5th, 2016, 11:25am
 
The waste pipe goes straight into the ground and everything looks okay. I think I need to call someone in to sort the problem out - please could you suggest what sort of tradesman would deal with this? Many thanks.
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Re: Help to locate source of unpleasant odour!!
Reply #8 - Feb 5th, 2016, 11:44am
 
if you have checked all the waste traps etc then my best guess would be that you have a dead mouse under the floor, in the ceiling or in a stud wall. If you can't find it then there is some comfort in that the smell will stop but it will take a while.
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Tika
Re: Help to locate source of unpleasant odour!!
Reply #9 - Feb 5th, 2016, 12:31pm
 
Wouldn't the smell be continuous then? It is random, and more of a "poo" smell - sometimes immediately the fan is on, sometimes after a while and sometimes not at all! However, there were droppings under the bath and holes sealed with wire wool implying that there had been a problem with rats......but the floor is all concrete and the chimney breast where the fan is seems solid.
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Re: Help to locate source of unpleasant odour!!
Reply #10 - Feb 6th, 2016, 9:29am
 
We had a dead rodent in our wall and the smell was worse when the weather was damp and when the wind blew from a certain direction so ours was quite variable too. The smell is vile though and if your smell is definitely of sewage I would think it is one of the traps leaking air when the fan is on creating a negative air pressure in the room. If you have a concrete floor then the bath trap will be very shallow, unless they have dug out a hole underneath, and this would be the first thing to check. If you have a shower then their traps can leak, Matki make a trap where the trap has to be clicked in place every time it is cleaned.

You could try putting all the plugs in and covering the overflows with masking tape and seeing if that cures it.

I did go back to a job where they had a bad smell in the bathroom but it was more of a musty smell. Turned out the ceramic sink had an inner and outer skin, there was an internal crack and the void would fill with water which eventually created a musty smell. These sorts of faults can be hard to track down.
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Tika
Re: Help to locate source of unpleasant odour!!
Reply #11 - Feb 8th, 2016, 2:53pm
 
Thanks for your suggestion. I have now tried putting all the plugs in and covering the overflows with masking tape, but it made no difference.

Could an explanation be that when the vendors refurbished the bathroom, they somehow managed to put the fan into a different flat's flue and that flat has a more powerful fan than ours, so when their fan is on it forces the bad smelling air back through our fan into our bathroom?
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Re: Help to locate source of unpleasant odour!!
Reply #12 - Feb 8th, 2016, 6:22pm
 
I thought the smell was worse when your fan was on? But if you think this may be a possibility you could swap the fan for an Icon extractor, these have a shutter system that closes completely when the fan is off.

But if the smell is coming from someone else's bathroom that would mean that their bathroom must smell foul!
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« Last Edit: Feb 8th, 2016, 6:23pm by woodsmith »  
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Tika
Re: Help to locate source of unpleasant odour!!
Reply #13 - Feb 9th, 2016, 1:02am
 
The smell is ONLY when our fan is on, never when it is off. I imagine there is some sort of non return system when it is off, although it is not visibly closed. I thought perhaps that if our neighbour had a more powerful fan than us, the pressure would be higher in the flue than our bathroom when his fan was on and so, in the case that our fan was operating, the negative pressure would allow the bad smell into our bathroom. Is that a possibility?  I don't know how I could check this theory; I doubt that I would ingratiate myself with my new neighbours if I go round asking who is making bad smells! Is there a type of fan that would prevent air coming in when operating?
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Re: Help to locate source of unpleasant odour!!
Reply #14 - Feb 9th, 2016, 8:39am
 
There are two main types of fan, ones with an anti back draft shutter and ones without. If yours had no shutter it would let more air back into the room when it was off and if it has a shutter it would close if a neighbours fan was creating more pressure than your fan, and probably make a lot of noise in the process so it doesn't seem logical that this could be the problem but sometimes this sort of problem defies logic.

Have you tried running the fan with the door open? That way you won't build up any negative pressure in the room. Other than that you could get an electrician to replace the fan with a more powerful one and see what that does. You might even find a mouse in the old fan.

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Re: Help to locate source of unpleasant odour!!
Reply #15 - Feb 9th, 2016, 10:29am
 
If the fan is working properly then it sucks from the room, next time you get a smell do a smoke test, incense stick should do.

If the fan is pulling take the stick around the room to check where its pulling air from.

What is outside, around you, smells inside should be noticeable, more so when you first come in from outside.

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Tika
Re: Help to locate source of unpleasant odour!!
Reply #16 - Feb 9th, 2016, 12:26pm
 
There is no shutter; I suspect it is a bottom-of-the-range Silavent fan, so it is a mystery why the smell is not evident even when the fan is off. Although it sucks in a tissue held nearby, it has little effect on anything very far away. Having the door open makes no difference either way.

I am not familiar with chimney construction, but would I be correct in thinking that my flue starts from the ground and that other flues start on their respective floors? If so, then it is not possible that our fan has been put on another flat's flue, but is it possible that a fan in another higher up flat accesses our flue? In that case, would a more powerful fan solve our problem?

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