Life of 'Push Fit' plumbing - for waste.

I've always favoured solvent weld waste for plumbing the waste from sinks, showers, bathes etc, especially in areas you can't later get to (under the floor, behind panels etc). Obviously, you need to have some fittings with the rubber/plastic rings at points you need to disconnect to, for example, clear a U bend or bottle trap, but for all other fittings, solvent weld, if done correctly, seems to be fit and forget.

I happened to look at some push fit fittings today - not for use in the house (to build a converter for a motorhome waste outlet) and saw a fitting which, while ideal for my job, I'm not sure I'd trust long term tucked away in a area I could get at. It sealed via internal O rings, which simply sealed (hopefully) against the outside of the waste pipe as you pushed them in the fitting. In my application, the odd drip wouldn't be the end of the world, the converter is outside the vehicle. However, if you used one of these in your house and the O ring was damaged- perhaps due to a burr on the cut pipe, or perished in time, you could end up with a long term leak you wouldn't know about until some damage had been done.

Unlike the fittings with a screw collar, in which the seals can be seen before you do final assembly, the seals are hidden in these fittings.

Obviously people use these beasts, they were on sale in one of the 'sheds', which had a good range of them (the reason I went there- I was looking for ideas to solve the problem). But I'm curious, has anyone seem one of these fittings fail?

I suppose the same is true of push fit fittings for clean water- again something I've not used, favouring solder fittings in hidden places and compression where disconnection may be required later.

Reply to
Brian Reay
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IME they work well and are very reliable in service. They can also be dismantled if required. You do need to cut the pipe ends clean, and also de-burr them. Assembling with some silicone grease also helps.

Not had a failure on one, although not used one for many years. Like you, my goto solution is solvent weld, but there is nothing wrong with push fit. They allow for a little rotation and repositioning after fitting as well - this may be a good thing or bad thing depending on the circumstance.

The ones for water supply / CH have multiple O rings normally - they also operate under more pressure than a typical waste fitting.

There are times where the ability to thread a pipe into a space (like through holes drilled in joists is invaluable. (although you can use compression fittings on plastic pipe with the right inserts if you want)

Cheers,

John.

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Reply to
John Rumm

The only way I have seen them fail is outside in sunlight where after about 30 years on a south facing wall the grey PVC pipe essentially turns into a brittle chalk like substance that breaks at the slightest knock. Once in position the bio film inside the pipe is probably enough to keep the thing from leaking. You do need to debur the pipe since any scratch during assembly could lead to leakage. But a boxcutter does that job quite easily. Nice thing is you have plenty of time to adjust it.

I'm not a great fan of the push fit fittings for clean water more because of their expense than anything else (preferring old style soldering) if it is accessible or compression joints if not.

Reply to
Martin Brown

Sorry - had to snip a lot.

Our sink was done about 40 years ago, in push-fit. I decided, due to the rather warm summer, to replace the water trap that was difficult to keep clean/unstinky with a HepVo and replace the whole lot at the same time. Now, AAUI, the pipe and fittings are polypropylene so I used black pipe. The material might not have been PP 40 years ago. It had gone rather friable - job had to be finished as just gripping the pipe tightly caused damage. This is on a NW-facing wall. All of the joints were sound and didn't leak. As I used silicone grease on the new fittings, I positioned the clips to allow for expansion but hold the pipe so that it couldn't be pushed apart at the joints by a large rush of water.

BTW, I put a Viva Magna waterless trap in the new pipe, outside and in series with the HepVo, to see if it would function after a good fros. Sod's Law - only -1 so far, so I might take it off, ensure that it's wet inside, put it in the freezer and then, next day, run cold water in gently to see if it opens. Possibly the ice won't sick to the silicone rubber flaps. If it's OK the bathroom will be re-piped and the Mac Valve put outside, shielded from sunlught.

Reply to
PeterC

To paraphrase Rami Malek: if you think that is huge I pity your wife ;-)

Work out where the fittings will be if you can, and tape up those bits of pipe, so the bits you seal on will be protected, or pad the holes you need to draw the pipe through.

With some systems like speedfit there are O ring seals on the outside of the pipe inserts, and those will mate with the internal surface of the pipe that ought to be pristine.

Reply to
John Rumm

The pushfit fittings for water supply / CH have a design life of 25 years. I hardly ever use them myself (the design life of my plumbing > 25 years so pushfit isn't suitable). I have had some pushfit O rings fail at around

12 years where the appliance had pushfit ports itself.

I do use pushfit for temporary plumbing. (Pushfit end-caps are a 'tool' which I would expect to find in any plumber's tool kit.)

Having said that, waste water is under much less pressure and much more limited temperature range. All other things being equal, I would expect longer O ring life here.

Yes, when I use plastic pipe, I use standard compression fittings.

Reply to
Andrew Gabriel

Had one fail here a little while ago, installed in the early 1980's. Others of the same vintage didn't take kindly to being dismantled and reassembled. Selection box of O rings had some of a suitable size.

Reply to
Dave Liquorice

Snip huge Sig

Has anyone come up with a solution /help to avoid scratches on the outside of Hep etc pipe when being cabled through rough holes in joists etc?

Reply to
Jim K..

It's the "- -" I find makes all the difference in practice ;-)

Mmm the latter would mean bigger holes in joists.. not necessarily wise in thrifty modern construction!

Oh yes I'd forgotten about them.

Reply to
Jim K..

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