How to connect 22mm pipework to 3/4 BSP bar mixer shower.

[paulg1]

I'm replacing a bath with a shower in my ensuite. I've exposed two 22mm H/C pipes which previously fed the bath and the ensuite basin. These will eventually feed the shower and basin (nothing else).

The shower I'm trying to fit - a Mira Atom ERD - requests 1/2 BSP inputs which it then converts via a couple of offset adapters to 3/4 inputs to the bar itself.

The simple thing I can think of is to tee off the 22mm pipes with 15mm and use a pair of 15MM X ½ BSP couplers to join to the offset adapters

The questions I have on this:

• What's the point of these offset adaptors provided with showers? Why go to 3/4 BSP via 1/2 BSP? Is there a reason they are offset rather than straight?
• Given I have 22mm pipes from the boiler and mains am I better off not reducing to 15mm? Even if just for a foot or so? If so is there a product available which will allow me to bypass the adapters and go straight from 22mm to 3/4 BSP on the bar.
• I've been reading on pressure and flow rates and I'm not 100% sure I understand everything, but it seems to me that reducing to 15mm will reduce the flow (and maybe the pressure marginally).

Other comments

• Combi boiler pressurised system.
• I haven't measured the pressure in the system - but the mixer shower in the adjacent family bathroom performs fine.
• Shower installation instructions: http://resources.kohler.com/plumbin...erd-bar-valve-installation-and-user-guide.pdf

 

[muggles]

Those offset things are horrible. Chuck them in the bin and buy these instead.

If you're on a combi boiler, it's almost certainly only 15mm pipe going in and out of that anyway, so 22mm pipe is pointless and will actually cost you more to run, because you'll run more water away before the shower gets hot. Strip out as much as possible and convert to 15mm.

 

[paulg1]

Thanks Muggles. I'll look into those fixing kits. More connections where I can get at them later sounds good to me.

As for the 15mm pipe: I'll need to get into the loft to check, but assuming you're right about the boiler using 15mm pipes I see your point.

 

[Hot&Cold]

does your combi supply sufficient hot water flow & pressure for your intended shower whilst other water outlets are in use,combis differ