Will 15mm pipe instead of 22mm reduce water pressure on mixer shower?

[cooa99]

Hi, my central heating system the gravity fed .... with hot tank in airing cupboard.

I am in middle of a DIY installation and about to replace existing bath mixer tap (with shower head) to just a bath mixer tap and then install a wall mounted thermostatic bar mixer shower, the exposed type.

We do get a decent pressure to the shower head with no complaint for the current setup.

When I removed the bath, I then realised that the pipes to the bath are actually 22mm but wall mounted thermostatic bar mixers use 15mm pipes. Since I will now connect the Wall bar mixer to the existing hot and cold using a T Joint, my fear is that a reduction in pipe width will result in a lower water pressure to the shower head. Am I right or wrong?

 

[terryplumb]

Pressure is the same ,however the flow rate may well be less.

 

[cooa99]

Pressure is the same ,however the flow rate may well be less.

That's has got me a bit confused with flow rate added into the mix. Does that mean that water spry coming from the shower head may not be as good as before?

Also I was planning to use copper pipe with push-fit elbow joint behind the tiled wall. Is that safe or I should solder elbows to the copper pipe?

Thanks

 

[johnny2007]

Solder is better in that scenario.
Nobody can give you an answer without being there.
A few moons ago a customer asked something similar and to have a definitive answer I connected the thermostatic bar and tested it, including shower head at ceiling height before doing anything else.
It worked fine and customer was happy, so I proceeded with fitting the whole bathroom.
Do the same.

 

[terryplumb]

That's has got me a bit confused with flow rate added into the mix. Does that mean that water spry coming from the shower head may not be as good as before?

Yes .Check the specification of your intended shower valve ,it should give you the minimum pressure required for its optimal performance. The hot and cold supplies to the mixer must be equal pressure ,so the cold can't be from mains ,it must come from the same loft tank that supplies the hot water cylinder. Flow rate is measured in litres per minute ,i.e how many litres of water will flow from the shower in one minute,and that will almost certainly be less with a thermostatic mixer valve ,than what you currently get from your bath tap.

And soldered fittings are more reliable than any other type.