Numpty soil pipe questions

[Tim S]

Hi,

Question 1 ==========

I have a new 110mm brown pipe coming out the floor, ready to take kitchen, bath and hot cupboard dehumidifier, plus local sink (which is directly over said pipe).

So I need at least 2 or 3 take off boss sets for 40-50mm, vertically stacked.

1) 40mm rear take off virtually on the floor. This is for the bath, needs to be bang level with the floor in order to get a 1:50 fall to the other end, 5m away, assuming bath drain is 100mm off the floor. One 90 degree bend involved. This isn't ideal, but it's the best that's possible with the house layout - that's why the bath is getting it's own drain.

2) The next one up, rear, needs to be fairly low, but is less critical, as it's a straight 3.3m run to the kitchen sink, dishwasher and spare plumbed position (I have a freezer here, but I'll design it to take a washing machine). Maybe I'll do this in 50mm with a fairly steep fall.

3) 40mm 1m run for airing cupboard dehumidifier and waste hot water dumping for solar heatbank (no solar yet, but if installed, needs to be able to dump water in the event of overheating). Maybe another boss for this, of maybe tee into kitchen pipe.

4) 40mm side connection for local sink.

So I was thinking to use 2 of these:

welded onto brown pipe (which I assume is uPVC - is there any other type?) and jointed with scraps of 110mm pipe.

I'd top it off with this:

fit would allow disassembly, but they're much more bulky and I don't have a lot of space.

Does this seem sensible?

Question 2 ==========

Boiler and other washing machine position (not in kitchen) needs waste. Originally I was going to go out the wall and take advantage of a gully drain about 1m along. However, I've since read about freezing problems with the drip-drip of a condensing boiler in winter, going out a long external pipe.

Option 1 is move the gully drain.

Option 2 is that there is a 110 pipe coming out the floor behind a wall, right next to the boiler/washing machine alcove. This is for a loo, but I suppose I could use a 90 degree boss tee like this:

of a plain bend. It might be that I'd need a air admittance valve[1] in the top of this (on a stub of pipe obviously) as this is at the top end of my set of drains and I don't have a vent pipe. Mind you, the 6" local sewer is only 14m away via 3 junction pits, so I wouldn't expect much suction normally.

[1] Or venting outside and up on 50mm pipe would also be an option - this is an outside wall with a low lead roof well away from opening windows.

Assuming the top of the washing machine drain stack pipe is higher than the loo pan top, is this a bad idea or OK? I can see that it might be an idea to make sure the washing machine u-trap is also higher than the loo, other wise it's liable to back fill with crappy water.

Many thanks - sorry for such stupid questions - haven't played with 110mm drains much.

Cheers

Tim

[Calvin]

I think you should read the drainage part of the building regs, they are available online at the "Office of the Deputy Prime Minister" (odpm) website. They give you all of the detail on what's allowed and what isn't so at least you'll know if you are breaking the rules :-) but remember that the rules are there for good reason, often to do with whether it will work in the long term. Or not.

From memory a waste stack can only be non-vented (which is what you propose) under certain very limited conditions. That rule is there to prevent problems with the water being sucked out of traps when other co-connected drains are used. Ignore that one at your (very smelly) peril. The stack can be vented with an air admittance valve but you then need (again from memory) to extend it to above the flood level of all connected fittings.

[Tim S]

Calvin coughed up some electrons that declared:

Cheers Calvin,

I figured there would be at least one air admittance valve in a land-locked bathroom in the middle of the house. At the other end, the loo I mentioned, which is next to an outside wall, I do have the option for either method.

Personally, I prefer vent pipes - durgo valves make funny farty noises and a vent stack has little to go wrong, especially as it will be all of about 3m high (subject to clearances from windows and boiler flue, as required - I have the docs to check later).

Do you happen to know if a vent pipe *needs* to be 110mm or is 50mm allowable? Personally, for 3m ish, I reckon 50mm will be more than adequate, but that's without reading the regs.

Do you reckon I'm on the right track with the set of fittings I'm aiming to use?

Cheers

Tim

[Calvin]

IIRC the there's a limit to the distance below the ground to the horizontal pipe where you don't have air admittance. The worry seems to be all about sucking traps so they no longer make a proper seal. Thinking about it, your arrangement has a bath trap in it with a longish run too. Bath traps are often shallow and so more prone to this sort of problem. Long horizontal pipe runs have the potential to carry water at full bore over a long distance which also means they have a lot of "suck" as the bath approaches empty. Anyway it's all in the regs.

For item (2) on your list don't forget you can get manifolds which go under the sink and allow the connection of other stuff relatively easily. Often they have a spigot for a washing machine waste which is blocked off at purchase and needs opening out for use - sounds just right for you.

Your choice of connector is fine but personally I'd go for a push fit for the connection to the brown as I like the idea of being able to rework it one day if I need to without having to trash the floor etc. They're not especially bulky. Do remember that any unused bosses can be trimmed back to gain that extra few mm (yes mine was that tight).

The obvious solution to your washing machine / loo connection is exactly as you describe. In this case I don't think it does need an AAV provided the top of the pipe is above the pan flood level. There's no reason the 40mm pipe should ever see the waste water from the loo as that enters at 90 degrees offset - that's why the fitting is designed the way it is.

[The Wanderer]

Why not a waste manifold?

if they're available as solvent weld.

[Tim S]

Calvin coughed up some electrons that declared:

OK - I'll download them and have a read. I know about the general idea of not sucking the traps dry - but I'm not up on the actual numbers of what works and what doesn't.

That's an option - I noticed these in B&Q today.

Yes indeed. I was playing with push-fit versus solvent. 2 solvent spigots get reasonably close bosses in the vertical plane - but as you say, push fit allows the whole assembly to be fiddled with, though I can't get the bosses as close.

Cool. Thanks :)

Cheers

Tim

[Tim S]

The Wanderer coughed up some electrons that declared:

Hi,

I did see those. Decided they wouldn't work so easily (partly as there's not much space between the wall and the 110) in my case - I really need two take offs, one over the other:

Plan view

Bath | ! | ! | ! | ! | ! | ===Wall===================================|** Kitchen Sink o +++++++++++++++++++++++*|* o o | |* o | |** Dishwasher Basin | |* | |** Spare | |

The o's are the 110 coming up through the floor. === and | are walls

+++ are 2 pipes, one over the other. Bath pipe is lower.

! is where the bath drain pipe does a turn and off through another wall.

• is the kitchen pipe.

Over the 110 is a basin and a small cupboard enclosing the drain fittings.

[Tim S]

And today we learnt the hard way....

That Marley boss inserts from B&Q are incompatible with Screwfix spigots...

The joys of waste pipes!

A cheap mistake (refundable anyway) - the first of many I'm sure...

Tim

[Tim S]

Calvin coughed up some electrons that declared:

I met the BCO yesterday and skimmed the regs this morning.

He confirmed I should have a vent pipe to atmosphere somewhere, to cope with any positive pressure in the sewer - fair enough. He pointed out, and I just found in the regs, that the vent pipe only needs to be 75mm, which means 82mm soil pipe in practise.

Local builder's merchant (small chain, very helpful) stock Hunter Plastics pipes and fittings and these look like the best range with the most flexibility with a good stock of 110 and 82 parts.

Regarding the ideas on having removable stuff: As I need the joint to the floor pipe to be as low as possible - I'm looking at parts to present a push fit socket in the floor, level or just above with the finish[1], which will mean a solvent-pushfit adaptor of some sort glued to the 110 under the floor (I'm not keen on a push fit joint completely buried in screed). Then I can push fit whatever assemblies required into that.

I'm less bothered if I need to solvent weld stuff above - as I could potentially pull out the complete assembly from the floor and make a new one if needed. But I agree, I think it would be foolish to weld a complex assembly onto the rising pipe - never get it out again.

[1] I might need to make a creative exception to the 110 that's grey water only as I really really do need a bit of 40mm to come off bang on the floor finish, for the bath. It's the only way to get any sort of drop. Quite surprised that the regs say I only need a 1:90 fall from a bath. I thought I'd bent the rules with a 1:80, so that's good.

So for the loo that does the washing machine, boiler and soil stack vent, I thought I would use one of the 110mm tees with side bosses that someone mentioned. The side boss faces the right way to go through the wall for the machine and boiler. Loo onto side of tee obviously. 110-82 adaptor on top of tee, going up though roof, *or* out through wall and up, with a vent cage on top.

Cheers

Tim

[Tim S]

Quick question:

If setting a 90 degree bend, or tee onto a rising 110mm pipe, is there a "best height" to set the horizontal junction at, so that any loo can be made to fit cleanly?

The rising pipe is at the back and in the corner relative to the loo (ie it's on one side of the loo, not directly behind the pan connector) - so I'd expect to use one of those 90 degree sideways bend couplers.

Or is it a case of "lower the better"?

For example, if I set a push fit socket more or less flush with the floor finish, would I have a good chance with:

the rising pipe

and a pan connector, like

a bit of 110mm between them?

Sorry for such daft questions...

I'll not be fitting the loos for a while as both floors need screeding and finishing - however I do have a need to connect the grey wastes up fairly soon.

Cheers

Tim

[Ian_m]

> Onto the rising pipe

> with a bit of 110mm between them?

Just make sure you do it right with vent pipes. My brother earned a fortune as a plumber retro fitting air vents into soil stacks in a new housing estate in London where 82mm self admittance valves had been fitted.

Basically if you flushed the loo whilst bath was emptying you could pull the water out the bathroom sink trap, thus leaving the sewer venting into the bathroom. His mods were fitting 110mm self admittance valves (as 82mm can only be used in limited circimstamces, single outlet/loo ?), these were either fitted in a white box on external wall (nice) or in plasterboard boxing in rear of fitted cupboards in adjacent room. Also the bath was replumbed straight to the stack rather than the feed from the loo.

When I redid my bathroom and had to relocate the self admittance valve I did consider using a smaller 82mm valve to gain extra room, but after listening to my brothers advice an experience just stuck with 100m AAV. I think there are restrictions as well as the number of bends you are allowed in the 100mm pipe before the AAV, so be careful.

[Tim S]

Ian_m coughed up some electrons that declared:

>>> Onto the rising pipe

>>> with a bit of 110mm between them?

Hi,

I'll be using an open vent, not an AAV. I might have one AAV on a separate branch out of necessity, so I'll bear your comments in mind (bathroom basin into loo connection, alas no choice here).

Cheers

Tim

[The Natural Philosopher]

Thats effectively what I have here..in the top is a 110 to 75mm reducer and the stack is then 75mm or something. carried away to where its pongs are not a problem.

Do get the adapter as low as possible. the run from the loo to the stack needs to be at a 5 degree downslope. Get the bog and measure it all, or install loose and pack up up by screed/tile depth and see if it all fits BEFORE you screed. There is nothing wrong with using a solvent weld joint below screed level if it makes it all come out right. Loos ar not soomethng you move so often that the push fit stuff will come loose.So that adpter can be glued in place.

Not sure why you need a right angle though..is the loo offset from the stack?

Believe me, these are not daft questions. Redoing sub screed plumbing is a very messy expensive business.

But buy the pans and test fit them before you screed..please.

[Tim S]

Hi

The Natural Philosopher coughed up some electrons that declared:

Sounds good - seems I'm generally on the right track.

>

Yep - rising pipe is in the corner of the room, so it's offset by width of bog + knees (or whatever)

That's what I was thinking - as I need to design the system without either a bog or a proper floor, as I need the grey water connections first.

Having said that, if I buy the bog when I'm ready to do the floor screed and tiles, it wouldn't be a disaster to modify it then - but nicer to get it right first time.

Sound advice. As the bog will be going in as soon as the tile grout sets, this is eminently practical.

Thanks!

Cheers

Tim

[Tim S]

Hi

Another quick numpty one:

When using boss connectors (eg 40mm into 110), how does one open out a blank boss (that's where the boss collar exists, but is blanked - I'm not talking about strap on bosses)?

Holesaw I assume - or am I missing something, eg are they designed to punch out?

Ta

Tim

[Bob Mannix]

If it's an old pipe don't try knocking it out! They get rather brittle and the hole may end up a lot bigger than you expect (BTDTGTTS)

[Tim S]

Bob Mannix coughed up some electrons that declared:

Hi Bob

No, it's all new uPVC parts. One of those things I've never done before. It would need a hole saw deeper than any I have too, which made me wonder if there's a secret method.

Cheers

Tim