Bath mixer taps with shower head attachment

[millsy]

Is there a way of regulating the pressure required to prevent the shower flow on bath mixer taps tripping back to the main outlet (ie. button drops down). If I put the tap on cold and lift the shower attachment button the water flows thru the showerhead ok , however if I move the tap just over half way towards the hot setting the button releases.

My hot water is being fed by a worcester bosch 240 combi, and my taps are the same as the ones sold on ebay using link
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=1282&item=4365482292&rd=1

 

[kevplumb]

check valves

 

[millsy]

There's a screw underneath the pull up button, where the shower lead connects and there is a spanner type (2 flat edges for a 10mm spanner) on the shaft of the button, are these the valves?

Currently they are both at there tightest position, but I've played arround with them and it doesn't seem to make much difference?

Could it just be that the pressure of my hot water is too low ?

 

[kevplumb]

put check valves in the pipework

 

[millsy]

Sorry to be nieve, but what's a check valve?

 

[kevplumb]

non return valve stops the cold pushing the hot or visa versa

 

[millsy]

I removed the spring from within the shower lever, and it now works fine.