plumbiing in sink and taps

[jelly]

When i get around to it i will be replacing my kitchen sink and taps.
The taps i will be fitting are monobloc taps.I will be replacing the pipework leading up to the taps as the sink is being situated in a different place.
The cold water is fed from the mains (obviously) and the hot from a tank upstairs.After reading various articles i wanted to ask a couple of questions.
What various valves etc do i need to fit along the pipe before it reaches the tap.For example i have heard you need a check valve.Also someone said a restricter.
What is the difference between a single and double check valve
Does it need to be fitted on the lowest pressure pipe (hot water) only
Can the check valve act as a isolater valve or do i need to fit one of these as well.

 

[peter anderson]

You don't need check valves. You only need a rectrictor if the water pressure is too high, I believe. You just need an isolating valve on all pipes.

 

[jelly]

I also forgot to mention i am fitting an outside tap and washing machine.

 

[peter anderson]

according to the readers digest diy book outside taps require a double check valve (as close to the new tap as possible), and washing machines require single check valves on hot and cold. Put isolating valves on the hot and cold washing machine pipes but there is no mention that you need one on the outside tap but personally I would put one on.

The book says that you should tell your water company if you want to install an outside tap because there may be an extra charge. This may not apply if you have a water meter but I'm not sure.

 

[jelly]

Thanks Peter
I was going to fit the tap to a flexi-connector with an isolater but can only find flexi-connectors with compression fitting one side and tap connector the other with a isolater or flexi-pipe with no isolater and compression both sides.I know i could fit an isolator on its own but am trying to cut down on the amount of connectors i have as you have to have copper pipe between each one.You can't just simply connect a flexi-pipe to a isolater.
I also have readers digest DIY book but its old but i could have overlooked it as it was a long time since i looked at that part.

 

[peter anderson]

Hi jelly,

Do you mean you can't find a flexi-tap connector which is already connected to an isolating valve? Try a plumber's merchants/ supply shop or buy one online.

 

[jelly]

Not quite.I haven't brought the monobloc tap yet but i understand it will have 15mm (i assume) tail pipes.These could be connected straight to my isolater.However if the pipes were 12mm i would have to fit a reducer,then a bit of pipe for it the join with,then a isolater.If i had a flexible-pipe with a isolater incorporated i could just connect to the pipes either end with or without a reducer (depending on pipe dia).
Or could i use the the non-compression fitting end of a flexi-tap connector (the one that fits to a normal tap) on a compression fitting.I assume the threads are the same.If this is the case.Job done.
You see there are flexi-pipe connectors with compression fittings both ends or flexi-tap fittings with compression fittings at one end and just a bolt the other to connect to the tap.Could i use this end on a compression fitting instead.Because for some reason the normal flexi-pipe doesn't have an isolater.

 

[taydo]

buy an external tap with built in dbl check valve. definitely fit an isolater to it inside the property so you can turn it off in an emergency lag exposed pipe work

in simple terms a single check valve is needed if any backflow of water will change the taste or colour or temperature of your drinking water

A dble check is needed if any back flow will make you ill.

so you need a dbl check for your outside tap coz there is a possibility that you may suck water out of your pond and poison everybody in the street.

if unsure fit dbl check anyway.

if you are fitting flexi connectors make sure they are ok for drinking water
I have been to a few jobs where the rubber hose inside reacts with the chlorine and flouride giving a bad taste

 

[jelly]

Thanks Taydne last thing.I have got an extension to my Kitchen. The washin machine is in the extension.I already have a outside tap.The water is tee'd of to the washing machine and outside tap.
Can i just put a double check valve before this tee.Therfore the contaminated water would not get into my drinking water but would go into my washing machine.Highly unlikley.Its just that the pipe to the washing machine is under the screed floor and is close to the outside wall where the outside tap is and would be tight trying to get a valve in there.
Also do you know if these check valves can act as an isolater as well.They look like they have got a screwdriver slot that you can turn

 

[taydo]

as long as contaminated water cant get into the main supply you will be ok

the ones I buy do not have isolators in built that bolt or screw is not an isolator

 

[jelly]

Thanks thats brilliant.I don't think i will use flexi-pipe as you said.The tails on the monobloc tap are pretty bendy and as long as the rest of the plumbing is close to them i won't have a problem.Thanks again