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;

http://www.screwfix.com/p/floplast-m...5-x-25mm/17684
with
http://www.screwfix.com/p/copper-mdp...2-x-25mm/25970

or
http://www.screwfix.com/p/jg-speedfi...5-x-22mm/49708


I'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

On Wed, 20 Jun 2012 21:02:45 +0100, "MartC" noone@here wrote:

First question is what to use to
go from 25mm MPDE to 22mm Cu;

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.

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?

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!)

2) double check valve after manifold ball valves on all pipes out to the
garden?

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.

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?

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

Fred wrote:

On Wed, 20 Jun 2012 21:02:45 +0100, "MartC" noone@here wrote:

First question is what to use to
go from 25mm MPDE to 22mm Cu;

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.

Sorry to answer 1 step out - but yes, there is a brass coupler for MDPE to
22mm copper - on the BES website.

He

http://www.bes.co.uk/products/168.asp

11329

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.

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?

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!)

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

--
Tim Watts

"Tim Watts" wrote in message
...
Fred wrote:

On Wed, 20 Jun 2012 21:02:45 +0100, "MartC" noone@here wrote:

First question is what to use to
go from 25mm MPDE to 22mm Cu;

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.

Sorry to answer 1 step out - but yes, there is a brass coupler for MDPE to
22mm copper - on the BES website.

He

http://www.bes.co.uk/products/168.asp

11329

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 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

"Fred" wrote in message
...
On Wed, 20 Jun 2012 21:02:45 +0100, "MartC" noone@here wrote:


2) double check valve after manifold ball valves on all pipes out to the
garden?

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.

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.

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?

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)?

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?

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?

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


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

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

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.

No header tanks, mains pressure cylinder.

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

HTH