I'm about the plumb my new kitchen sink but I also need to tee in two other pipes: one for the dishwasher and one for the outside tap. I would like isolating valves on each of these. The valves need to be accessible, so is there a right way to do this?
Option one is to fit all the pipe work on the wall behind the cupboard but the disadvantage is that I would need to cut a hole in my lovely new cupboard.
Option two is to fit all the pipe work inside the cupboard. I think this could be more hassle having to drill holes for each pipe to go in and out and align these holes correctly. It also means that to move the cupboard, one would have to disconnect all the pipes first. However, I realise kitchen cupboards are rarely moved, so perhaps this is not really an issue. I guess either way I have to butcher my new cupboard!
Perhaps if there is a leak, this method is more likely to damage the chipboard as with option one the water runs down the wall instead?
Perhaps there is no right answer and it is just personal preference?
I think it usually ends up being a combination of the two. Often the incomi ng mains is coming up the wall, and the washing machine supply may be fixed to the wall in the washing machine recess.
It also depends on the cabinet. My sink unit had a gap at the top where you could see the wall - this was required to accommodate the sink bowl which needed some of the "service void" space, so the "hole" was already there.
In my case, the pipes to the rest of the house and the pipe to the outside tap were fixed to the wall but the stopcock was inside the sink unit. The p ipes that were fixed to the wall had a bend at the top that poked into the sink cabinet for convenience later.
I used full bore lever valves for everything - they are just, well, better than service valves, and also reversible, which I needed since the water fl ow was reversing direction as the stopcock was also being relocated.
The sink mixer tap was connected with those flexible hoses that have a rubb er sealing flange. They were quite happy to connect to one side of the full
-bore lever valves (which are really designed for compression olive and nut , but in practice sealing on the "end" of the valve body seems to work fine ).
And the washing machine connection (cold only) was fitted at the back of th e sink unit pointing towards a hole in the cabinet side. All washing machin e connections (inlet, outlet, power) are made inside the sink unit which me ans the washing machine can be pushed right back to the wall - I hate it wh en they stick out !
One thing to keep in mind is that the outside tap feed should also have a double check valve in it. Place this inline before the isolating valve inside - that way you can protect it from excess back pressure caused if the tap freezes, but shutting off the isolator.
Inside presumably?
Fraid so
I would go for mounting it behind, and cutting access holes so you can get to the taps.
I cannot remember which order I put my isolator and double check, but just did a google, and I believe the water regs say words to the effect: "Outside tap installations must have a inline double check valve fitted inside the building after the isolation valve. This type of valve prevents contaminated water being siphoned back into the drinking water supply."
Not sure of the reasoning - maybe its to facilitate replacing the valve it it fails, but I get your point about protecting the valve. My intention is to open the outside tap and drain it every winter.
I put it all behind the cabinet back panel, but add a removable hatch for access to the service valves. If the mains stopcock is also in there that needs to be quickly accessible though. Mind you almost anything I did was better than what I replaced, see
Yup, that is the "normal" way, but I found that if you forgot to turn off the isolator, and the pipe near the outside tap freezes, it puts so much back pressure onto the double check valve as to distort and wedge the second part of the floating valve plug into the body of the valve such that it would not let water pass in the normal direction after that.
As with Simon's, my sink unit has a back to it that is not full height. So valves fixed to the wall are accessible above. Also, the back is removable (after the shelves are taken out), so any leaks etc can be fixed without removal of the remaining cabinet structure. The rigidity of the unit is provided by wall and worktop fixings. For valves requiring regular (annual) operation I have lever operated. Maintenance valves are screwdriver slot type.
Perhaps that saved a pipe burst ! Bit of a pain to change the valve though. I have quite a long stretch of copper pipe indoors including a 2 bends between the valve and the outside, so your scenario would be unlikely. I did wonder if using plastic pipe would be more forgiving on a freeze, since it is more flexible than copper. But I've just never got into plastic.
I had been doing this after every use of the outside tap since I don't use it much. And the level isolator valve is very easy to get to under the sink. We'll see if I get lazy ;-)
I don't know if it helps at all but the last two kitchens I have fitted were with Ikea units which famously (!), don't have a useful service void behind them. I therefore ran the pipework at 'skirting' level, which could then be accessed by removing the plinths. In the event of a leak (which is one of your concerns and always one of mine, but thankfully has never materialised), it would then miss the cabinets and only damage the plinths, which should be easy to replace if necessary (assuming a waterproof floor, of course).
That still means bringing the pipework for the taps into the unit where the sink is, which I did vertically through its base, in the corner of the unit. So a little bit of butchery, but only two 19mm holes (15mm for the pipes and a bit of wriggle room). It only took a modicum of lying upside down and the obligatory swearing (of course) to connect up. I have to admit to using compression joints there, as I was a little concerned about using the blow lamp in a tight space under a chipboard cabinet (I know, no spirit of adventure!). If I had had any sense at all, I would have installed the sink unit first, plumbing it before putting it in place and worked everything back from there. Of course plastic pipe would also allow a bit more flexibility here, but I've never used it on a job like this (yet).
I connected the outside tap behind the dishwasher (obviously depends on the layout, but the connection doesn't have to be immediately beside where it goes through the wall) so that is all quite readily accessible by pulling the d/w out. Mr R has already mentioned check valves, of course.
I think the biggest lesson I have learned in this is to add as many service valves as sensible: They're cheap and let you build things up in stages during assembly as well as allowing you to isolate any later problems with a minimum of fuss. You seem to have that in mind already, by the look of things, but a little bit of redundancy doesn't hurt, in case one fails to shut off completely when you need it.
Of course, you'll probably have to butcher a bit more for your waste too (I took this through the base of the sink unit in my current kitchen too, and it has sufficient fall, but that's a temporary job pending a comprehensive re-fit). In an ideal world, that would probably go straight through the back of the cabinet and the wall behind.
Collars for pipes are cheap and available, so you can pretty up the inside of your butchered cabinets quite easily. Have fun
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