low pressure shower valve

I don't think you'll ever get a decent flow by gravity alone with that pressure.

Are both feeds at the same pressure - i.e. cold directly from header tank and hot from hot cylinder fed by the same header tank? If so, consider using a booster pump such as this if you can find somewhere to put it.

Do the sensible thing and install a water softener and mains pressure tank.

I agree. A pump will probably work out cheaper as well.

We simply have a pump to achieve decent shower rate of flow. Why do you say installing a water softener and mains pressure tank is the sensible option?

Mike

Oops - looks like I omitted to a link for a pump. Try this one

Just noticed that it claims to be "regenerative". Not sure what that means in this context. Anyone?

pump-1-5bar/20423#_=p

Thanks for your comments but didn't want to go as far as installing a pump. Especially as the shower in the other bathroom, which has the same head of water obviously, has a reasonable flow . I should have mentioned this in m y original post. Anyway, decided to go ahead and fit the replacement Mira Coda valve. The fl ow is now adequate, while not being "forceful", and better than with the ol d Grohe valve. So I'm happy I did it. However it could be that most of the improvement came from fitting the new filters in the inlet ports. You shoul d have seen the crud that was obviously partially blocking the old filters! So, I now have a perfectly good, used Grohe valve that I have no use for. I f you're interested keep your eye on Ebay in the next few days. I also have the riser bar, flex hose and shower head for the Mira shower th at I didn't need. I bought the complete kit from Screwfix which was cheaper than buying the valve alone. £90 for the complete kit. This will be o n Ebay also if anybody is interested. Thanks again for your help and advice. Cheers Petek