Plumbing question

[Flyfisher]

I'm working on a downstairs cloakroom complete with a shower. The waste water pipework will also collect water from a washing machine and sink in an adjacent room. Not a problem as such but there will be a number of joints, tees etc.

I would go for push-fit for ease of installation but am wondering about the reliability of the rubber seals. As some of the joints will probably be fairly inaccessible by the time I've finished I'm wondering of welded joints would be a better idea?

What are the panel's thoughts and recommendations regarding push-fit vs compression fit vs welded PVC pipework?

 

[robgil]

i would go with glued plastic my self. fit and forget. just remember that when you push the pipe into the fitting to then turn it half an inch or so , just to make sure the glue creates a water tight seal all around. :wink:

 

[Jon Maine]

I'm working on a downstairs cloakroom complete with a shower. The waste water pipework will also collect water from a washing machine and sink in an adjacent room. Not a problem as such but there will be a number of joints, tees etc.

I would go for push-fit for ease of installation but am wondering about the reliability of the rubber seals. As some of the joints will probably be fairly inaccessible by the time I've finished I'm wondering of welded joints would be a better idea?

What are the panel's thoughts and recommendations regarding push-fit vs compression fit vs welded PVC pipework?

I would have thought it was obvious, own a period property, you must get stuck up!!

Without a doubt solvent weld is a wise decision. As Rob says smear well and twist upon fitting to ensure no leaks.

You could always go one better to 1.5" copper with compression joints..........

 

[Feltwell]

Welded every time. So much neater, so easy to do, and less worries about future leakage or pipes getting knocked and dislodged from fittings.

 

[robgil]

too much glue is better then not enough. when i was working on new builds my boss would always say he wanted to see the glue dripping onto the floor.

 

[Lime]

If using welded PVC ensure the joints are sound before sealing up forever.

Just a simple question Flyfisher, but I wonder if you intend to connect the sink, washing machine and shower all to a shared small bore pipe?

 

[MdB]

I was thinking along the same lines. Connecting two waste pipes together using T's can cause one to suck the water out the U bend of the other I think. There are all sorts of info on this in the approved regs. Separate wastes to the main stack is best I think I remember reading.

 

[DaveBrigg]

Our plumber installed the central heating using push fit plastic, which was plastered over. Two and a half years later we realised that there was a leak. Not sure when it happened, because the leak point was hidden by furniture, but it could have been there for over a year. It was a nuisance chiseling out the pipe and patching up afterwards, but on the other hand, having soldered copper throughout would have added a few hundred pounds to the price. For a small job in a difficult location safest is best, if only to stop you laying awake wondering whether there might be a leak or not.

PS. Congrats, I think that was your 3000th post!

 

[robgil]

was it a defect or bad installation? a defect should be covered by the guarantee (poly pipe is 25 years) and a bad install should have had the plumber back out to fix it.

 

[Jon Maine]

was it a defect or bad installation? a defect should be covered by the guarantee (poly pipe is 25 years) and a bad install should have had the plumber back out to fix it.

Most likely bad installation or plumber damaged item, easy to kink those pipes and form a weak point or not cut the end of the pipe off squarely and take a chunk out the o ring on the way in, or simply not push it in enough.

My experience is if it is put into the hands of a competent person, a good one.

 

[Flyfisher]

Thanks for all the comments, especially Lime's point about connecting everything to a single outlet pipe. I hadn't thought of the possible implications so I'll change things to separate pipes for the sink and shower. The only slight problem might be the washing machine as this is closer to the wall outlet than the sink; I was intending to tee it into the sink pipe but it will be after the sink u-bend - is this likely to be a problem, given that the washing machine will discharge into an open pipe (thus reducing any suction effect on the sink u-bend)?

Glued pipe seems to get the unanimous thumbs-up so I'll go with that. That was my instinct anyway but I'd only ever used the push-fit type before so I just needed a gentle nudge in the right direction. So thanks for that.

Interesting that Jon mentioned copper waste pipes. An existing 1960s bathroom uses copper for all the waste outlets, which I'd never seen before.

I'm doing all the main water pipework in soldered copper as I don't entirely trust the push-fit stuff - even though I have used it for temporary pipework without any problems at all. For the amount of pipework involved the cost difference is negligible and DIY takes out the biggest cost anyway.

As for my 3000th post, thanks for the congrats Dave, although I suspect commiserations to everyone else is more in order.

 

[MdB]

Remember with glued connections you get one chance of getting it right and that a hacksaw is the method of deconstruction...

You will get flex in an up down left right sort of way due to the flexibility of the pipe but you will get very little or no flex in rotation. This isn't really a problem, you just have to make sure you get the position of the joints right as the glue sets.

 

[robgil]

was it a defect or bad installation? a defect should be covered by the guarantee (poly pipe is 25 years) and a bad install should have had the plumber back out to fix it.

Most likely bad installation or plumber damaged item, easy to kink those pipes and form a weak point or not cut the end of the pipe off squarely and take a chunk out the o ring on the way in, or simply not push it in enough.

My experience is if it is put into the hands of a competent person, a good one.

we used to have to mark it with a permanent marker and then push it in. this didnt always happen but the pressure test would always pick up on mistakes by blowing the joint apart.

 

[robgil]

Remember with glued connections you get one chance of getting it right and that a hacksaw is the method of deconstruction...

You will get flex in an up down left right sort of way due to the flexibility of the pipe but you will get very little or no flex in rotation. This isn't really a problem, you just have to make sure you get the position of the joints right as the glue sets.

if its complex i normally build it all up first and mark each join across the join with a line so that when i strip it all down again to apply the glue i know exactly where it goes when building it back up.

 

[Penners]

Lime's point about connecting everything to a single outlet pipe. I hadn't thought of the possible implications so I'll change things to separate pipes for the sink and shower

You can overcome the problem of "pulled" traps in a pipe that serves several wastes if you include a Durgo valve on the end of the run (by "end" I mean farthest from the drainage point). Turn the pipe 90 degrees upwards and (at a point that will be the highest in this particular system), place a Durgo valve on top. This will admit air whenever anything drains into the system, eliminating pulled traps.

Pushfit or glued? Well, I agree with everything that's been said about the reliability of glued, although I've personally never had a problem with pushfit. The only rider to that is that pushfit allows for adjustments and adaptations - solvent welded is... well... welded!

http://tinyurl.com/yavks9f

PS: make sure your Durgo valve is indoors, so that it can't freeze up, and ensure that it's the same make as your pipework. Not all 40mm (or 32mm) is the same size! :evil:

 

[DaveBrigg]

Most likely bad installation or plumber damaged item, easy to kink those pipes and form a weak point or not cut the end of the pipe off squarely and take a chunk out the o ring on the way in, or simply not push it in enough.

I suspect that it was not fully pushed in, because by the time it had been excavated, the end had popped out of the elbow. However, it was not detected early on because the walls were newly plastered, and dried from the top down. We also had an earthquake which broke windows and loosened the chimney stack, which may have made the situation worse.

The repair was fairly cheap, but what caused a much bigger problem was that all of the rust inhibitor had gradually drained out of the system. The leak was probably responsible for some of the air that got in too, with the result that the system, and in particular the plate heat exchanger became clogged with sediment. It took someone with a fancy cleaning system nearly all day to pressure blast each radiator in turn, and then a couple of weeks to soak the heat exchanger and flush out the rust. The plumber tried to fix the fault by replacing the pump; when this didn't work he stopped returning calls, although he didn't charge for the pump either. We now have both on the go.

 

[MdB]

Not all 40mm (or 32mm) is the same size! :evil:

I've fallen into this trap too...

.. and never ask for it using imperial measurements. Ask for inch and a quarter and you could end up with anything.

 

[Lime]

Air admittance valves (Durgo) are all very well but make a noise that can be quite annoying or frightening if you don't expect it.
However it isn't just suction that has to be worried about as a large quantity of water flowing through a small pipe can create pressure too for which the valves do nothing.
This can cause backflow, particularly in showers and baths, as well as smelly air trapped in the pipe being pushed through the traps.
I would never plumb a shower with anything else and it is required LBC too.

Using a vent pipe is better.
See H 1.22 page 11
http://www.planningportal.gov.uk/PpWeb/jsp/redirect.jsp?url=http%3A//www.planningportal.gov.uk/uploads/br/BR_PDF_ADH_2002.pdf

The washing machine doesn't need a separate waste as most sink traps now have connections for dishwasher/washing machines fitted above the trap.

My personal preference waste-pipe-wise is to use well-supported pushfit.
Make sure the ends of the pipes are perfectly smooth without any rough edge to catch debris within the pushfit joint.
Also an extra piece of advice, don't expect the plastic pipe to support itself.
Use plenty of clipped support the whole length or, failing that, strap wooden battens to the straight pipes between supports to give them rigidity.

 

[chuckey]

wrt marking up pipes on first build up. Use a line down the pipe and connector to get angle of rotation and I use a mark 1/4" away from end of connector on the pipe. This is so when I strip it down I can be sure of adequate penetration of the pipe and on build up the mark is away from glue/solder joint so can be seen.
Frank

 

[Flyfisher]

Thanks for reminding me Penners; I meant to ask about those very air-admittance thingies I noticed on the screwfix site. I've only previously ever seen larger versions used on foul pipes (we have one next to a lavatory where, presumably, it was preferable not to continue the waste pipe through the roof. I wondered about their use in grey water pipes.

The pipes I'm installing won't actually connect into a main foul drainage pipe. They will discharge into a gulley first - does that make much difference?

The problem with the washing machine is that it is quite a way from the sink. I'll try to put a sketch together.