DHW pipe type

[Pocster]

Hey all,

 

It would seem that still copper is best for all internal water. But what about PEX and all the equivalents?. A pressure connection does worry me compared to the certainty of a welded joint. But with plastic I an do the majority of the install hence the appeal.

 

So; is it still copper all the way??

 

Cheers

[PeterW]

I think most are Hep2O all the way these days - copper for first metre or so next to a boiler but the rest is plastic all the way. 

[Pocster]

Thanks. Didn't come across Hep2O when googling. So this is the 'new' pex ?

[joe90]

Hep 20 is recommended by our resident professional plumber and having received a sample from the company I am sold on it. I was a Luddite and used copper only as it was " bound to be better than plastic" but I am now converted, being able to feed long lengths in and out of joists etc is far better than lots of soldered bends and Joints and although plastic fittings are more expensive you use far fewer of them. Yes copper where it shows or next to boilers.

[jamiehamy]

I'm literally ordering my HEP20 pipe as I type this - single runs to each outlet from the manifold - no joins anywhere that can't be accessed. Will hopefully spare me from years of worrying that I didn't quite get a join right somewhere!

[Jeremy Harris]

I did the same, after a lot of deep thought I concluded that my prejudice against using plastic was outweighed by the ease of having long runs through inaccessible places, where fixing a leaking joint would have been a pain.  My decision was influenced because we didn't have water on site to leak test at first fix, either, so using plastic, with no hidden joints anywhere, made a lot more sense.

 

I'm now a convert, having plumbed the whole house, as plastic is a heck of a lot quicker to install, and its a lot cheaper than copper too.  The only downside is that it's not easy to get any exposed pipe work looking neat in plastic, so I switched to copper wherever there was a bit of visible pipe.  Easy to do as the 15mm plastic fittings accept 15mm copper pipe as well.

[TerryE]

As well as the ease of fitting, cost and significant risk of leeks, the Hep2O / manifold approach (or equiv from other vendors) is a lot easier to balance and has significantly less heat losses.

 

If it's not too late in your design process, then centralise you heating / DHW tank / thermal store, manifolds, etc. in a single service area.  That way your copper runs are only a few metres long at most and the hot works can be properly lagged to minimise thermal loses.  You will still end up dumping heat from the hot radial runs, but this can be minimised if you split your hots into low-flow and high-flow and plum the low flow hots in 10mm.   

[Pocster]

Oooooo

 

It does seem nice. So In theory can you do a run say from boiler to tap with zero joins? i.e. curve the pipe rather than elbow it?

[Jeremy Harris]

12 minutes ago, pocster said:

Oooooo

 

It does seem nice. So In theory can you do a run say from boiler to tap with zero joins? i.e. curve the pipe rather than elbow it?

 

 

Yes, with the proviso that you need a bit of copper right next to the boiler, and can then convert to plastic from that.  The stuff curves around a gentle bend OK, and comes in long rolls (I think I bought a 100m roll).  We have no joints hidden anywhere, every single pipe joint is accessible, which is one of the big advantages, I think.

[TerryE]

17 minutes ago, pocster said:

 So In theory can you do a run say from boiler to tap with zero joins? i.e. curve the pipe rather than elbow it?

 

We do have a few hidden joins -- some of the runs travel vertically down the walls but need to come out at 90° to the wall (e.g. for the shower fittings) so these have elbows just behind the plasterboard.  Other than that, none.    If there is a leak at one of these, then at least it's just a matter of cutting a hole in the board fixing and repairing.  But you want to buy a load of Hep2O end-stops, and then you can at least pressure test before boarding out -- if you don't want to take the risk.

[Pocster]

Great 

there I was thinking mdpe was the main option over copper .

 

[TerryE]

No, and in fact MDPE is approved for any use where it could be exposed to direct sunlight.  Just search the forum for Hep2O and there's loads of background material.

[Pocster]

I've read on some other threads about Hep2O and it does sound great (nice when you learn something new!!).

 

I see the general idea is a manifold for hot and cold that supply everything so hopefully no (or very little joins); also a stop tap at the manifold per run. I intend rainwater harvesting for 2 toilets, 2 out door taps, 1 washing machine. Presumably the feed from the RWH could go to a separate manifold which in turn feeds those utilities?

Would it be wise (assuming such a thing exists) to put a pressure gauge on each Hep2O outlet?. The reason being I could balance the system so when 2 taps are running the shower doesn't run dry (for example).

This a good plan ?

[TerryE]

@pocster.  Seek and ye shall find.  Search the forum for hep20  and you'll see some active threads on all this -- including mine.

[Pocster]

Cheers 

[RichS]

6 hours ago, TerryE said:

You will still end up dumping heat from the hot radial runs, but this can be minimised if you split your hots into low-flow and high-flow and plumb the low flow hots in 10mm.   

 

 

So what is the definition of low flow and high flow????

[TerryE]

• High flows are the ones where you'd get pissed if they dropped in pressure / went of of mixing balance when someone turns on a shower or started running a bath: the main sinks, the baths, the showers.
• The low flows are what they say and flow rate isn't that important: the toilet cisterns, the hand basins, bidets, etc.

[Nickfromwales]

17 hours ago, pocster said:

Would it be wise (assuming such a thing exists) to put a pressure gauge on each Hep2O outlet?. The reason being I could balance the system so when 2 taps are running the shower doesn't run dry (for example).

This a good plan ?

Pressure gauges on each outlet will see you go crazy. Static pressure and dynamic pressure will give two completely different readings.

For e.g; you'll have all the gauges showing max static pressure when no outlets are being used. Flush a loo and they'll all drop. Flush a loo whilst the bath is running and they'll all pretty much drop off, maybe altogether, and so on. 

Dont confuse pressure and flow . You can have water coming out of the shower but be using all of the dynamic pressure, ( so a gauge would show next to no pressure ), but you'd have adequate flow. This is ENTIRELY case-specific, so each scenario will differ, but my point is that the gauges would cause more confusion than help. 

My main advice would be to upsize the cold mains to 22mm straight after the stopcock if possible as that run is the one that has the biggest demand on it. E.g. You open the shower valve and a blend of hot and cold comes out, but it's the single pipe feeding the cold to the house that has to provide both sets of pressure & flow. ? 

 

[Pocster]

Thanks Nick!; I take your points; much appreciated!. I didn't really want a past time of watching pressure gauges! 

[Nickfromwales]