# Plumbing, self cutting valves, any plumbers on here



## Clean-my-sxi (Feb 5, 2008)

Asked a question about an outside tap a little while ago, and i have decided to fit a proper copper pipe system instead of using one of those tap kits.

It will only be used for my pressure washer really.

Im looking at still using a self cutting valve for the t-piece coming off the mains pipe (due to the placement of the pipes)

Ive seen one that self cuts and allows a 15mm copper pipe to fit straight into it, the only thing is the self cutting valve has what appears to be a 6mm whole in it, so from the 15mm mains it will go through this 6mm hole to the new 15mm outside tap system.

Does anyone know if this will alter the water pressure/flow at all.


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## djohn (Mar 30, 2007)

Hi, Yes they do alter the flow a little, sometimes quite a bit. They don't actually cut the copper pipe away completely, more of a small 4 - 6 mm hole as you say, leaving the shoulder of the cut pipe inside the 15mm copper pipe which adds to the lack of pressure. Unless you have good pressure to start with then this method would be my last choice.

If you can turn the water off without much trouble then much better and quite easy to cut the 15mm copper and use a T piece + valve preferable a gate valve [One with a large round red handle on0 as these do give full bore. Not normally recommended for mains pressure, [Stop**** instead] but in this type of work will be fine.


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## Clean-my-sxi (Feb 5, 2008)

ok cheers mate, as said i was considering the self cutting as its such a awkward space to get to and the ppes seem quite frim in place, so if i cut one im not sure how much movement there will be to slide the T-piece into place.

Plus the self cutting valve with 15mm compression fitting on i have seen actually says its for gas, but i cant see why it cant be used for the water system aswell.


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## djohn (Mar 30, 2007)

Measure enough of the original copper pipe to cut off by gauging the distance from the shoulders of the T piece. You'll find once cut there will be enough movement in the pipe to slip the T piece on. The brass one you mention is fine but don't over tighten the nuts at each end when fitting, use a little boss-white or similar round the olives to ensure a nice water tight seal. You can also pop into B&Q and buy the T-Piece in 15mm plastic which is just as good, easier to fit as well and perfect for use with the copper pipe.

If you wish to you can buy a length of plastic pipe to finish off the tap fitting once you have made the connection to the copper, very easy to use, don't take off the nuts at each end of the fitting, just slide over the copper and new plastic pipe if you use it then tighten the fittings, again don't over tighten.

You'll find the plastic option is much cheaper and the chap in B&Q will give you a quick demo of how to do the work if you ask him, also he'll sort out exactly what you need.

I did mine last summer, cost less than £18 for brass outside tap with fitting for hose and wall plate plus 3 metres of plastic 15mm, one plastic T-piece and two 90 degree elbows, [bends] all in plastic requiring only a few turns at each end of the fitting to tighten the nuts and took less than 20 minutes to do the work although I do have 20 years of practise. Shouldn't take you more than 45 to 60 mins. Good luck.


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## Chris_R (Feb 3, 2008)

I have the similar self cutting tap set for our outside tap. We have really good water pressure here but I still find my PW "pulses" since I moved over to a Karcher - the old one didn't have anything like the same flow rate.
Knowing what I know now about plastic plumbing I would go that route if I need to do it again. I replumbed the majority of our new bathroom I put in using a combination of Plumbeasy (B&Q) and Hep2O (Hepworths). Really is easy to do, it takes a little planning ahead due to the bulkyness of the connectors in comparison to traditional copper fittings, just make sure you push it all the way home and double check each IS pushed all the way in and no leaks.


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## Griff (Aug 11, 2007)

As a Plumber, the hep2o is the best route for the diy'er as it's push fit it really is a simple job to install an outside tap, I would also fit an internal stop valve so you can shut off the outside supply if the weather gets too cold
Tom


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## zedzedeleven (Jan 16, 2009)

As a non plumber I can also give hep2o a thumbs up. The first job you do seems a leap of faith as you turn the water back on and wait for the leaks ! Pleasant surprise when it proves to be water tight. The biggest challenge is finding a shop that has either a good display of the various fittings or a helpful assistant that doesn`t mind helping a novice. A bit of a challenge in the plumbers merchants of old, if you weren`t Tom from abc plumbing you were made to feel unwelcome. Just asking for one item got an "eyes cast heavenwards" and a knowing glance to the cognoscenti queuing behind you. Then it was "Brass or copper?", " Metric or imperial?" "left or right handed?" "compression or yorkshire?" etc. Used to make the back of my neck go red. Much better in B&Q where it`s all laid out for you to browse over. Twice the price though. My tip would be get a good pipe cutter if using copper, they are inexpensive and well worth it.


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## Clean-my-sxi (Feb 5, 2008)

TBH i had sort of decided to go with the self cutting valve which has a 15mm compression fitting on. Then from here i just need 3 brass elbows, 4 small lengths of pipe and the tap.

I was thinking that it shouldnt really alter the pressure as isolation valves have very small holes in, like 6/7mm and they dont alter the pressure so why should the self cutting valve. 

However, Chris R seems to of experienced lower pressure due to using one.


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## Griff (Aug 11, 2007)

Ok a tip when using a self cutter, do not over tighten the saddle, if you do, it distorts the rubber part of the saddle, this can make getting the self cutting part a ***** to start self cutting, and could also lead to a leak, dont panic if you get a small amount of water leaking as you start the self cutter, it would be better to do the job with the water turned off if possible, I only used self cutters if a stop**** couldn't be found, they leak a little untill fully home, one other thing, they are not the strongest of fittings so if its in a cupboard wher things get chucked in try to support it with the two screw fixings

Tom


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