At current I just have a bath in my house and want to refit the bathroom and include a shower over the bath. I was hoping to fit a thermostatic mixer as part of the bath taps so that no real plumbing is involved. However the cold is straight from the mains and so will obviosly push all of the hot out. Is there any sort of bath tap/shower mixer that can deal with an unbalanced supply or is the only answer to change it so that the cold bath tap is fed from the header tank? Any solutions to my problem would be gratefully recieved.