Random referred banging & odd smell mystery

[DR1001]

Folks,

I have two unrelated (i think) mysteries that are driving me mad and I’m looking for your help.

1)

At night, in the winter, when we flush the toilet, empty the sink or bath in the bathroom, which is right next to our bedroom, there are bad pipe knocking sounds that appear to come from the bathroom wall and then through our bedroom ceiling. They are a percussion of regular bangs, fast and loud at first, petering out, though sometimes it takes hours for them to go. Sometimes they’re also very loud.

- This only happens in the winter.
- This only happens at night (can’t be recreated during the day) and heating off/on seems to be irrelevant.
- We are top floor flat in a three storey 1990s block in London.
- Plumber says it is just random referred noise: nothing can be done. No rads need topping up, combiboiler is new ish and in good working order.

Any ideas?


2)

A night, in the winter, when we walk into the flat there is, perhaps three times per week, a grim dirty water smell right outside our kitchen in the hallway (no door). There are no obvious sources whatsoever. Plumber has been around cleaned out the kitchen pipes repeatedly and has no idea. Says perhaps it is a durgo value that is malfunctioning. But it’s been replaced twice already. My guess is that the smell emanates from bad pipework out of sight under our kitchen sink and a draught sucks the smell towards the front door. Though there’s no smell outside the front door.

So, assuming that the plumber isn’t an idiot, and thus the pipes are – from what he can see – fine, what can it be?

What does the fact that it ONLY occurs at night and ONLY during winter and ONLY sporadically say?

Any thoughts would be gratefully appreciated.

 

[oldbuffer]

1. Pipe banging:
1a. Don't know why only in winter.
1b. Typically, at night, mains water pressures are higher, as few people are using water.
1c. A 1990's flat is likely to have plastic pipework. There is a tendency for installers to leave the pipework insufficiently clipped, which allows it to move, possibly knocking against something solid.
1d. Likely to be very difficult to locate, need not even be in your property. Your action in running water may be sufficient to cause vibration in another flat.

Without knowing for certain where the problem originates there is no definitive cure. However, you might try adding a shock arrester to your incoming cold water mains as it might reduce vibrations in your own property or reduce the risk of them being propagated to other flats.

2. Dirty water smell:
2a. Is the air able to get to the Durgo. Sometimes they are boxed / tiled in so well that no air can get to them, and as they are air admittance valves, they then don't work.
2b. Could be water being drawn out of, say, the trap under the kitchen sink by other devices being flushed / emptied on the same pipe run. Anti-vacuum trap might work.
2c. Why only sporadically on winter nights I'm afraid I have no idea.

 

[DR1001]

Thanks for such a quick and thoughtful response, though I remain disappointed that you don't have any magical, simple solutions for me...

Sink issues: there is, I'm told, another larger durgo which is indeed boxed in so that might be malfunctioning.

Banging: b****cks.

Cheers

 

[DR1001]

I should have asked: would a shock arrestor do anything in my case where the issue is with pressure in waste pipes?

 

[oldbuffer]

The issue might appear to be in the waste pipes, but for water to flow in those pipes, one or more taps / flush valves must have been used. It is much more likely to be a hot or cold water pipe than a waste pipe causing noise. Waste pipes are under very low pressure and tend to be larger than water pipes. In the case of plastic pipes, waste pipes are generally more rigid than water pipes.

So I'd be very surprised if the issue was really to do with waste pipes.