Lower pressure rainshower head vs. Handset attachment

[plastics77]

Hi, just had new mains pressurised heating system and boiler put in and new bathrooms. Old loft tanks gone. New floor piping in bathrooms, but older piping left in kitchen.

The water coming from the rainshower heads is weaker than the handsets attached to the wall, which are at really good pressure in all the bathrooms.

Is there a reason why this pressure isnt there for the water coming from overhead shower which is much higher up?

Told that the pressure has been set at 1.5 bar, and the higher up the showerhead and larger the outlet, the lower the water pressure. If they crank up the pressure to get overhead rain showers more powerful, the handsets and bathroom and kitchen taps may not be able to cope?
Is that the case?

 

[steadyon]

1. You lose roughly 0.1 bar of pressure for every 1 metre rise in height.
2. However, that isn't likely to explain the different experience between a hand held shower and a rain head.
3. Are you really talking about pressure, or about flow rate. If the pressure driving the flow is just about right for a hand held shower, even the same pressure may seem much more diffused from a rain head.
4. If you have an unvented hot water system, then the pressure of both hot and cold supplies should be the pressure of the incoming cold water main, or the setting on the cylinder's combination valve if the mains pressure is greater than this setting. This assumes both hot and cold have been fed via this valve.
5. Look at the flow rate promised for your rain head at 1.5 bar pressure, it may be less than you thought. See manufacturer's literature / web site.
6. It is possible the older pipework won't take a greater pressure, but this could be tested with a pressure pump, and any rupture corrected. The pressure test should be to 1.5 times the normal working pressure, so 4.5 to 5 bar is about right.
7. A bit late now, but it would be sensible to take static and dynamic pressure readings of your incoming mains, together with the flow rate.

 

[plastics77]

Thanks Steadyon

3. Are you really talking about pressure, or about flow rate. If the pressure driving the flow is just about right for a hand held shower, even the same pressure may seem much more diffused from a rain head.

Not sure about how to tell the difference - flow is strong from the handset which is less than a metre below the overhead shower. It just seems a bit weaker/soft coming from the shower head above, compared to rain showers I've used in hotels etc. Maybe it is just meant to be like that, but just seemed odd!

4. If you have an unvented hot water system, then the pressure of both hot and cold supplies should be the pressure of the incoming cold water main, or the setting on the cylinder's combination valve if the mains pressure is greater than this setting. This assumes both hot and cold have been fed via this valve.

Yes, it is an unvented hot water system

5. Look at the flow rate promised for your rain head at 1.5 bar pressure, it may be less than you thought. See manufacturer's literature / web site.

It is a Grohe Allure 230 Head - on US website it says minimum recommended pressure 1.0bar, and at 80psi, 9.5L/min;
15psi is 1 bar, so at 1.5bar is ?22.5psi --> which would suggest a flow rate of around 2.4L/min - not sure if that is meant to be good or bad?

6. It is possible the older pipework won't take a greater pressure, but this could be tested with a pressure pump, and any rupture corrected. The pressure test should be to 1.5 times the normal working pressure, so 4.5 to 5 bar is about right.

They upgraded all the pipes to the bathrooms upstairs because all the flooring was lifted and changed upstairs. They said they pressure tested the system to many factors higher, but because they haven't changed any of the floors or pipes downstairs, if there is a problem or leak, that would be my issue so better to stick the system at 1.5bar.

7. A bit late now, but it would be sensible to take static and dynamic pressure readings of your incoming mains, together with the flow rate.

If there is an unresolved problem, could I ask them to do it - is it straightforward, if they are coming back to check on other things?

 

[WC1]

Might be obvious but - whip 'em both off and check for blockages?
Check the overhead is assembled correctly.
If you hold the hand held up alongside the head they should be the same pressure