Plumbing Questions

[MartC]

I've lots of pumbing to do - pretty much whole house, so hoping for a bit of help and advice here over the coming weeks.

I've got a new MDPE pipe into the kitchen, and then several others going back out to various locations (garden, garage, utility...). I was planning on making a manifold from 22mm copper solder fittings to distribute these, with full bore lever valves for isolation. First question is what to use to go from 25mm MPDE to 22mm Cu;

'm not well aquainted with plastic fittings, any opinions on the merits or otherwise of either type much appreciated.

Second batch of questions are more general regarding the use of check valves. My understanding is that these are installed at point of use, so I was planning;

1) nothing required at point of entry (manifold) and can use lever ball valve as main stopcock? 2) double check valve after manifold ball valves on all pipes out to the garden? 3) single check valves on hot & cold supply to mixer taps & shower valves that are not dual flow? 4) single check valves on flexi shower attachments that can reach baths/sinks/bogs? 5) any others (no bidets)?

For background the hot and (softened) cold distribution are mains pressure (the same pressure, except at kitchen & utility sinks where the cold is unsoftened and at higher pressure)

Thanks

Martin

[Fred]

I'm afraid I've never used MDPE so can't help you with that one. When I have used plastic pipe, I have always used brass compression fittings, never the proprietary plastic ones, so I suppose I would look for a 25mm to 22mm (or 25mm to 15mm) brass coupler.

If the MDPE is the water main into the house, then I think the regulations will state what type of valve you can use (but I am neither a plumber or a lawyer, so I could be wrong on this and all the above and below!)

You don't state what these pipes will be used for. You have to have check valves on outside taps to prevent water flowing the wrong way up a hose pipe and into the mains water.

I'm puzzled why you are using double check valves for (2) and single check valves for (3) and (4)? Do you know something I don't (quite likely)?

I've always used a double, when I have needed a check valve. Only because I read here that doubles were considered more reliable. Does a double reduce flow significantly more than a single?

Be guided by the instructions for your taps. Some taps may require you to fit check valves.

I'm not sure about the shower. Some people here may say avoid the valve if it will affect the flow. You are right that if the shower head can be submerged it will need one, but often the flexible pipe is routed through a part of the shower rail to prevent it falling that low.

I have heard some people say that toilets should have check valves but I don't think I have ever seen any that actually do. Similarly, I have never seen many check valves under sinks and basins. But then I am not a plumber so I haven't looked at thousands of toilets.

I don't think you've mentioned valves on the inlets of your loft tanks: CH and HW. They are recommended there.

As I said, I am not a plumber so hopefully someone who knows a lot more will be along shortly.

HTH

[Tim Watts]

Sorry to answer 1 step out - but yes, there is a brass coupler for MDPE to

22mm copper - on the BES website.

Here:

Beware - the brass tail is solid and will not take a compression fitting - you should solder a 22-22 coupler onto this with a stub of 22mm copper pipe to terminate as required.

The MDPE side is an olive and a pipe insert (important) and forms a compression joint which should be bomb proof. It's what I used.

You can use plastic MDP-copper (or universal) couplers, but:

1) They are bulky

2) Rely on a squishy doughnut seal and barbs to hold the pipe and I trust them a little less.

I used a 22mm full bore 1/4 turn valve - I am not aware of any possible reason why that should not be acceptible. Local regs *may* require a check valve (usually required on specific items as the PP alludes to later) but that is nothing to do with the stopcock.

Cheers,

Tim

[MartC]

I didn't come across that before, I'd have prefered it but I've already gone ahead and ordered the flo-plast couplers - tested to 48bar, according to the bumpf, so I trust they're fit for purpose but as you say they really are bulky.

Martin

[MartC]

Yes, for outside taps, and I'm fairly sure the valve has to be a double check type and must be inside, protected from frost.

Not likely, but I guess belt and braces double valve is not required for hot/cold contamination as opposed to murky pond water from an outside tap?

It's bound to, but probably only an issue for marginal grivity fed systems

The tap instructions are uterly useless, I wonder how any people actually know or bother with the regs requirements?

No header tanks, mains pressure cylinder.