Hansgrohe shower controller pipes

[Pete]

Just about to fit this Hansgrohe controller and wondered if anybody has fit one of these? I am just dithering (as we self-builder's do) because the two inlet connections which are the yellow discs are 3/4" and the two outlets are 1/2" which go th the shower itself. I have fitted 15mm supply pipes but the bit I am dithering over is should I have run 22mm seen as it is 3/4" or am I just over thinking it. I think I need to just get the appropriate fittings and use the 15mm pipe seen as I am using 15mm from the controller to the shower. TIA

[ToughButterCup]

7 minutes ago, Pete said:

... I have fitted 15mm supply pipes but the bit I am dithering over is should I have run 22mm seen as it is 3/4" or am I just over thinking it....

 

I've 'worried' the same problem half to death myself and in the absence of evidence, come to this conclusion : 

Maybe  the 3/4" issue has to do with supplying 2 separate 15mm outlets   at the same  time. In other words, in a shower for example, if it is possible to use both the overhead showerhead and the hand held wand at the same time, then the unit will work better with a 3/4 supply. 

 

 

[Pete]

Yes, had the same thought but with the smaller  1/2" on the outlet of the controller to the shower  then surely it does not matter if the supply pipes are not 22mm. @PeterWwill know!

[ProDave]

I used 15mm on both my showers (different make but same principle) to keep the volume of water and hence time for hot to arrive, to a minimum.

 

My only regret was I used full bore 15mm isolator valves.  I wish I had used the normal slightly restricted bore isolators to act as flow restrictors and reduce the maximum flow rate a little.

[Pete]

@AnonymousBosch, when you actually take the yellow discs out and have a look at the size of the hole in the brass casting it is quite small so my way of thinking is 15mm pipes will be ok (I think)

[PeterW]

Most of the pipe work inside those units are around 12mm so even supplying it at 15mm is adequate. 
 

Flow and pressure are two, but the real issue is balance. If you have a pair of balanced hot and cold 15mm flows they will have ample supply to support the shower outlet. It is when you have an imbalance toward cold then the overall will suffer. 

[PeterW]

1 hour ago, ProDave said:

My only regret was I used full bore 15mm isolator valves.  I wish I had used the normal slightly restricted bore isolators to act as flow restrictors and reduce the maximum flow rate a little.

Just put a flow restrictor in the shower hose at the head. 

[Pete]

17 minutes ago, PeterW said:

Most of the pipe work inside those units are around 12mm so even supplying it at 15mm is adequate. 
 

Flow and pressure are two, but the real issue is balance. If you have a pair of balanced hot and cold 15mm flows they will have ample supply to support the shower outlet. It is when you have an imbalance toward cold then the overall will suffer. 

Thanks very much, why do you have more doubts when doing it for yourself!

[ProDave]

33 minutes ago, PeterW said:

Just put a flow restrictor in the shower hose at the head. 

Too late now.  The reduced flow would get noticed.  I keep trying to say the knob does not have to be turned on all the way.

[ToughButterCup]

On 14/04/2020 at 19:32, ProDave said:

[...] I keep trying to say the knob does not have to be turned on all the way.

 

Simple , clear evidence that psychology has a part to play in plumbing.

"Not a lot of people know that." (Trump D. 2020)

[Jeremy Harris]

I've left a 9 litre/minute flow restrictor washer in our shower head.  Hasn't been noticed yet . . .