shower mixer flow rate

21 Oct 2003
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United Kingdom
I had a basic shower mixer fitted a while ago, to replace a defunked thermostatic mixer ( mira excel ). The flow rate from the new mixer is no where near as good as the old shower, although no other changes have been made to the plumbing.

I have just started to wonder if mixers have 'stops' or 'limits' to ajust the water flow rate, as these may not have been set correctly when it was installed.

Are there such settings?
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Ok, so where will I find them?
I assume in the shower mixer itself.

Its a modern style shower mixer with a single tilting leaver for temp/on-off.
There is a grub screw that will alow me to get the head off the mixer. There seems to be a small cover plug further back on the valve body, so possilbly a further grub screw.

I'll turn the water off before I start investigating, but what sort of thing am I looking at to adjust? ( screw/ leaver ). Is it likely to be close to the valve head futher back, near the water inlets.

( I know this is a very general question! without a shower make, but any help would be appreciated.)
Excels are made to be OK with low pressures, whereas most cheapie mixers aren't. Simple as that I expect. :( I doubt there will be a flow adjustment.
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There are different coloured restrictors supplied with most showers, and they go in the inlet of each side, take the hot ones out.
Yep, hate to agree with Chris R because he is known to bodge showers*.

But you should have replaced the Mira Excel with another one. Most of the cheap imported shower mixers have small waterways which restrict the flow on a gravity fed system.

If your new unit is thermostatic, you might be interested to know the most difficult thing about designing a thermo shower mixer is the response time when the cold water stops suddenly. The higher volume of water allowed through the mixer, the faster the response time has to be. Therefore, lower quality thermostatic units restrict the flow rate within to give them a better response time for scald protection.

A quality brand like Aqualisa or Mira will give a better performance. NB: If you are on a budget most Gainsborough showers use Aqualisa's internal mixing valves but have cheaper peripherals.

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