Afer purchasing a new house about 18 months ago from a national building company who shall remain nameless we had a really annoying problem for about
4 months of sewerage smells in our hallway (and only there) for several months, that naturally of course we were just imaging. This was the place the main waste pipe was boxed in - always the same, fine at night and morning, building up during the day and reaching its worst at about 4/5pm each day.Eventually, the problem was resolved after much badgering and they hadn't fitted the air admittance valve to to top of the waste pipe sticking up in the loft (yes, I know, how on earth did something allegedly part of a house inspection accidentally get missed off). Problem solved.
Now, as of 2 days ago, exactly the same problem has come back - so my question is, is it likely to be a faulty air admittance/dirgo valve? what's the likelihood of this failing? I'm of course about to do the obvious and try changing it, but if this isn't the case, any suggestions? I'm fairly new to the whole plumbing/drainage experience so even the obvious suggestions are welcome to at least remove possible sources from the list of options.
Cheers
daryl