Suggestions for low pressure bath shower mixer.

Hi DA
You are correct most thermostatic and ceramic disc types are either 0.5 bar or 1 bar suitable
You will need a mixer that has a 0.1 bar suitable (not even 0.2bar) mixer and even then with a hose as you have suggested the flow will be minimal
This one seems to fit the bill, you may need to fit a 1.75 m hose to got it high up on the riser rail and you will need to purchase a separate riser rail (as the don't come with the tap). Sorry if that's teaching you to suck eggs
And flow will still be minimal!

 

Other things to think of are a pumped electric shower from Mira and the digital version works as well. Shower pump or power showers these options will give you a great showering experience with out the extra power behind it, it will be a poor shower. The problem is the higher you lift the shower head the slower the flow and more unbalanced the shower will be so the blending of the hot and cold becomes difficult. I just wanted to through it out there.

 

Yes Jeff is right if you have mains cold water and gravity hot, then the supplies will be totally unbalanced.
A true "power shower" as Jeff suggests, will need a balanced supply hot, via Essex or surrey flange from hot water tank, and a separate cold down service from the cold water storage tank, to provide balanced supplies and a 6 amp electric supply going to the box on the wall

 

Maybe he could sit in the bath while he showers with the shower head just above him, to get the best flow! lol

 

Sorry to bring you bad news, DA I don't like people to install some thing and not be happy with it so I am as honest as possible. Yes in this scenario as it stands thermostatic valves will not work. Even with the washer type taps I think the shower will be poor and getting the hot and cold to to be stable is hard.
A pumped electric shower maybe possible, need and electrician to check if the power cable can be installed if it is possible the will only need to take a cold feed to the pumped electric shower or you could use a mains fed electric shower by taking the feed from the mains cold supply to the stored water tank. Just some ideas.

 

I would like to hear what Ideal Std have to say about it, I still don't know how they are going to defy gravity.

 

To get a thermostatic valve to work it has to have a balanced flow other wise the blending is not accurate. If you going down the rout of pumps try Salamander CT Force 15 TU it is small and compact and works a dream and is quite silent. This pump can boost the whole house so any shower valve can be used, most of the thermostatic bath shower mixer need at least 1bar to run. This pump can be installed at the base of the hot water cylinder I would suggest an Essex Flange for the hot feed. The warranty is very good on them I think 5 years.

 

This pump is for the whole house you can run just cold or just hot on its own. It has the cross over built into it it is different to the just shower pumps those can only be used on showers. As for the trickle Whoosh I have not had this problem in all 32 I have installed. Please follow the manufactures install guide then the pump will work to potential and have the full warranty, this pump is really a cut above the rest I have found and not so loud, if it is behind the airing cupboard door even less noise.
On the hot side use Warix Flange, Surrey Flange or the Essex Flange. On the cold side give it an exclusive feed to the cold and there will be no problems.

 

I like to use the Aqualisa Aquamixa Termostatic it works well on all systems and the cartridge is a breeze to replace, I have seen them more than 15 years old change the cartridge works like new. There are many out there it is more what your budget is.
The Aqulisa also has the shower hose coming from the top of the valve where many come from the bottom causing a hoop affect.
Aqualisa Midas 100 have worked as well, Mira Extra is another one, I do tend to go for branded ones as if anything goes wrong parts are easily replaced.

 

To true DA, good thing is that these have been tried and tested on a pumped system and performed very well so there will be no hit and miss involved, you know you are getting a quality product and it is going to work, install and leave. It is a bit like plug and play.