Hello,

I have heard you should not use a shallow bath trap if your bath
drains into the soil stack because winds blowing across the top of the
stack can suck the water out of the trap. Can the same happen to
toilets? I know if sounds daft but I went to a house that has stood
empty for a couple of months and the toilet pan was completely dry.
How else could the toilet have emptied? There was no sign that the pan
was cracked and I doubt it has been hot enough to evaporate?

The other strange thing was that the water had been turned off and
when it was turned back on all the taps spluttered as though the pipes
had been full of air and the combi boiler needed the loop turning on
to repressurise it. How had the pipes emptied?

And when the water came through the taps for a few seconds it was a
golden brown. What caused the colour? Whilst it was a copper colour,
surely copper is not very reactive? I am not aware of any roadworks
causing dirty water in the street.

Thanks in advance.

On Fri, 28 Aug 2009 20:27:02 +0100, Stephen wrote:

Hello,

I have heard you should not use a shallow bath trap if your bath
drains into the soil stack because winds blowing across the top of the
stack can suck the water out of the trap. Can the same happen to
toilets? I know if sounds daft but I went to a house that has stood
empty for a couple of months and the toilet pan was completely dry.
How else could the toilet have emptied? There was no sign that the pan
was cracked and I doubt it has been hot enough to evaporate?

A combination, perhaps, of evaporation and wind. In very windy conditions
I've seen mine go down by an inch or so as the water is rocked by the
changes in pressure. I'd assume that the lower the water gets, the less
will be slopped over, but if the level gets low enough the air could get
through and that would speed evaporation.
After 7 weeks in the Winter - house at about 12C - the water in the loo was
only a bit above the bend.

The other strange thing was that the water had been turned off and
when it was turned back on all the taps spluttered as though the pipes
had been full of air and the combi boiler needed the loop turning on
to repressurise it. How had the pipes emptied?

And when the water came through the taps for a few seconds it was a
golden brown. What caused the colour? Whilst it was a copper colour,
surely copper is not very reactive? I am not aware of any roadworks
causing dirty water in the street.

Thanks in advance.


--
Peter.
The head of a pin will hold more angels if
it's been flattened with an angel-grinder.

Stephen brought next idea :
Hello,

I have heard you should not use a shallow bath trap if your bath
drains into the soil stack because winds blowing across the top of the
stack can suck the water out of the trap. Can the same happen to
toilets? I know if sounds daft but I went to a house that has stood
empty for a couple of months and the toilet pan was completely dry.
How else could the toilet have emptied? There was no sign that the pan
was cracked and I doubt it has been hot enough to evaporate?

It can easily evaporate in that time in warm weather.

The other strange thing was that the water had been turned off and
when it was turned back on all the taps spluttered as though the pipes
had been full of air and the combi boiler needed the loop turning on
to repressurise it. How had the pipes emptied?

If you turn it off and one of the taps passes just slightly, the
pipewark can drain completely.

surely copper is not very reactive? I am not aware of any roadworks
causing dirty water in the street.

The main supply doesn't need to have been without pressure for very
long, for other people to use up the contents of the pipes and sediment
to be disturbed as the pressure comes back on.


and the combi boiler needed the loop turning on to repressurise it.

A completely separate problem - you have a slight leak somewhere on the
heating system. You don't need to loose much water for the pressure to
drop to zero, but it might be worth checking what ever it uses as a
pressurisation system (pressure vessel?).

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

In article ,
Stephen wrote:
I have heard you should not use a shallow bath trap if your bath
drains into the soil stack because winds blowing across the top of the
stack can suck the water out of the trap. Can the same happen to
toilets? I know if sounds daft but I went to a house that has stood
empty for a couple of months and the toilet pan was completely dry.
How else could the toilet have emptied? There was no sign that the pan
was cracked and I doubt it has been hot enough to evaporate?

Water will evaporate over time without it being hot.

--
*Forget about World Peace...Visualize using your turn signal.

Dave Plowman London SW
To e-mail, change noise into sound.

Stephen wrote:
Hello,

I have heard you should not use a shallow bath trap if your bath
drains into the soil stack because winds blowing across the top of the
stack can suck the water out of the trap. Can the same happen to
toilets? I know if sounds daft but I went to a house that has stood
empty for a couple of months and the toilet pan was completely dry.
How else could the toilet have emptied? There was no sign that the pan
was cracked and I doubt it has been hot enough to evaporate?


Here's a market opportunity perhaps. Has anyone seen a soil stack cap
that is designed to reduce the pressure drop that causes this? It must
be possible to make at least some improvement. I get the same. When the
wind blows, as it does in Norfolk sometimes, the bog level bounces up
and down.

Peter Scott

"Dave Plowman (News)" wrote in message
...
In article ,
Stephen wrote:
I have heard you should not use a shallow bath trap if your bath
drains into the soil stack because winds blowing across the top of the
stack can suck the water out of the trap. Can the same happen to
toilets? I know if sounds daft but I went to a house that has stood
empty for a couple of months and the toilet pan was completely dry.
How else could the toilet have emptied? There was no sign that the pan
was cracked and I doubt it has been hot enough to evaporate?

Water will evaporate over time without it being hot.

Damn right it will..
one of the buildings at the gec cov site had bog floors with a drain in them
so they could be washed down.
Trouble is they stopped washing them down and just mopped them.
They would smell like hell unless someone remembered to pour some water down
the drain every few days.
Its amazing how many engineers would either put up with the stink or just
didn't know you had to put water down the drain to stop the smell.

On Sat, 29 Aug 2009 09:19:45 +0100, Harry Bloomfield
wrote:

The main supply doesn't need to have been without pressure for very
long, for other people to use up the contents of the pipes and sediment
to be disturbed as the pressure comes back on.

Thanks. So it was sediment inside my pipes. I never realised tap water
was so dirty!

On Fri, 28 Aug 2009 22:46:51 +0100, PeterC
wrote:

In very windy conditions
I've seen mine go down by an inch or so as the water is rocked by the
changes in pressure

I don't know if this is the same thing but at home our bath and basin
wastes are tee'd together, I'm not sure why as it doesn't save much
pipe. When one drains the other "sucks". I cured this by fitting an
anti-syphon trap.

I see "air admittance valves" listed in catalogues, like these he
http://www.toolstation.com/shop/Plum...ves/d20/sd3136

I'm not sure what they are. Are they like the valve on my trap that
admit air when there is a partial vacuum in the pipe? Could I have
fitted one of these instead of a trap with a built in valve?

If so, why aren't such devices fitted on toilet pipes to prevent
siphoning of their traps?