Drain-waste-vent

Internal stack? Probably terminates in the loft with an air admittance valve on the top.

You can vent the stack indoors or in the roof space with an air admittance valve - very commonly used during the period when BR required soil stacks to be indoors - possibly arising from the Winter 1962/63 freeze up.

Doesn't that make the loft/house stink of s*it?

On Friday 06 December 2013 14:19 Mr Pounder wrote in uk.d-i-y:

Are you sure? Some stacks vent through a roof vent these days.

A few years back these valves were new & about $40 each. Takeup was slow.

The valve lets air in but nothing out. AIR ADMITANCE

According to the wikipedia page, air can be required to go both ways to equalize pressure.

I take it the external one is why when it's very windy the water disappears from my loo?

Just been in the loft to make doubly sure. No pipe and no vent. There is no vent on the roof. The waste water pipe from the sink goes directly down the grid in the driveway, as does waste water from the bathroom. The soil pipe from the bog disappears under the floorboards. The houses round here all have the vent pipe on the outside wall. I took the dog out and had a good look at the bungalows round here, not one has a vent pipe on the wall.

Thanks to the other guys for replying.

Aha!!! A grid. Performs the same function I would think.

Drain pipe?

You must have a a very bad case of flatulence to have that effect on the loo's water...... :-)

I've not been in Building Control for that long, but from my time, there has never been a proscription against external SVPs (in low rise housing anyway). The use of AAVs has only gained acceptance as far as the guidance is concerned in the last 10-15 years.

It's a bungalow.

Oh, you want more? OK. It's possible to connect a ground floor WC into a vented drain without its own vent stack, provided that the unvented branch is less than 6m long.

I suspect that the drain itself may be vented at its head, although this is more a Victorian/Edwardian kind of thing. If you live in a more rural area, older ways of building hung on longer into the twentieth century. These can be seen as cast iron columns on the sides of the end of a terrace, but sometimes as a small slightly oblong protrubrence close to a manhole.

Thanks for giving me more. I'll take a look at a few manholes when I go out.

It's actually to let air into sewer run to prevent partial vacuum when someone drain run flushes toilet. Most house now have a vent that vents through a tile in the roof ... for one of the sewer points .. and the others via an AAV.

Nothing worse then getting sucked down a toilet.

IME, that's usually a vent into a chamber with an intercepter trap, since it can't vent through the trap (or at least couldn't when originally built - usually the rodding cap has been removed by now, to act as an overflow bypass for a blocked trap).