On Mon, 17 Nov 2008 16:24:25 -0000, "John"
wrote:


Is the cold water tank filling properly? Is there any foreign body in the
outlet in the bottom of the cold water (Header) tank?


I've been in the loft and the tank was full, lid in place. I turned
the water off and drained the hw, all ok and nothing obviously
blocking the outlets. Tank refilled ok but no improvement in pressure.
It's now obvious, as well, that hw pressure is low at the taps but
obviously it's more noticeable when the shower doesn't work. I think
I'm at the limit of my capability now. I've got a plumber coming
tomorrow. Thanks to all for comments etc. I'll report back.