15mm push-fit vs copper

[ban-all-sheds]

1. No this is not about the aesthetics.
2. No this is not about what it says, if anything, about the skill or attitude of the plumber.
3. No this is not about how leak-prone the fittings are. Or not.
4. Simply this - are flow rates lower? Seems to me that for a given amount of pressure, as push-fit has a smaller i.d. than copper they would be.

 

[denso13]

Simply this - are flow rates lower?

Yes, but it may, or may not, be noticeable depending on the supply pressure and system design.

 

[ban-all-sheds]

Well - the pressure/flow rate at the kitchen cold tap seems healthy (not measured it), but by the time the water gets to the cold taps in the bathroom (so about 2m higher, and about 3-4m of pipe) the difference is very marked.

The flow rate by the time it gets to the 10.8kW shower (another 2-3m) is too low to trouble it, i.e. its less than the shower could cope with - maximum temperature is far too hot.

I'm asking because we have a bathroom refurb coming up, which will mean plumbing changes, and I was wondering if I should specify the use of copper rather than push-fit.

 

[denso13]

There shouldn't be a marked difference in flow rate over a distance of 3-4m, whatever pipe is used. I think i'd be investigating that first. Are you sure the bathroom is fed from the same supply as the kitchen? Is it just the cold affected?

 

[ban-all-sheds]

Are you sure the bathroom is fed from the same supply as the kitchen?

Yes - tee'd off under the sink - pipe (copper) runs in the wall to the bathroom above, where it becomes plastic. Also, to be fair, at that point it goes through an ugly mish-mash of elbows, more tees, and a valve which isolates the shower supply.

Is it just the cold affected?

The hot is from a combi.

 

[swbjackson]

The valve would be the most likely candidate for reduced flow rates. Some isolating valves can be incredibly restrictive.

 

[misterdubya]

1. No this is not about the aesthetics.
2. No this is not about what it says, if anything, about the skill or attitude of the plumber.
3. No this is not about how leak-prone the fittings are. Or not.
4. Simply this - are flow rates lower? Seems to me that for a given amount of pressure, as push-fit has a smaller i.d. than copper they would be.

Yes as copper nowadays is very thin walled. Old Cu pipe is as thick walled as plastic pipe.

 

[newbuildinstaller]

Then add the inserts into the plastic (speedfit especially) it must be near 10mm ID. And the 10mm or that matter must be 6mm ID.

But I would say a domestic install with a combi (so mains pressure) would be unnoticeable as to whether it was copper or plastic from the flow rates.

Also electric showers slow the water down a lot in order to heat the water before it exits the heat exchanger so this may be why the shower is poor compared to the taps

 

[ljrgas]

i would help but after reading your post im blind

 

[ban-all-sheds]

Also electric showers slow the water down a lot in order to heat the water before it exits the heat exchanger so this may be why the shower is poor compared to the taps

I didn't explain it well.

The shower could cope with a higher flow rate - it's a thermostatic one where the temperature is controlled independently of the flow rate.

At maximum flow, if we have it on maximum temperature it hurts, even in the depths of winter.

It's b*****ed at the moment, so I can't measure the flow, but OOI I'll time filling a bucket at the kitchen H&C taps, and the bathroom ones when I can find my round tuit.